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w2uey
|
Are anti-particles particles with a negative time value and that is why they are "destroyed" when they interact with normal matter with a positive time value?
|
I am not a physicist, but a physician. I heard one of my patients say this and thought it was too interesting a concept not to get further opinions on it, so better to ask reddit.
|
askscience
|
http://www.reddit.com/r/askscience/comments/w2uey/are_antiparticles_particles_with_a_negative_time/
|
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"[Searched](_URL_0_)\n\nRelevant [discussion](_URL_5_)\n\nOriginal question by [mindule](_URL_3_)\n\n > If antiparticles move backwards through time (Feynman–Stueckelberg interpretation), how can we produce/contain them for any length of time?\n\nTop comment courtesy [Amarkov](_URL_2_)\n\n > You're misunderstanding some fundamental concept. Antiparticles are, in the context of Feynman diagrams, equivalent to the corresponding regular particle moving backwards in time. This equivalence is very useful, because it means that rotating a Feynman diagram will also give a valid Feynman diagram. But it doesn't mean that antiparticles actually are particles moving backwards in time.\n\nRelevant [follow-up](_URL_4_) courtesy [djimbob](_URL_1_)\n\n > I'll take a slightly different stance than Amarkov/RRC. Basically in QFT, the math describing the wavefunction of an electron moving forward in time is exactly equivalent to the math of a positron moving backwards in time, and similarly the math of a positron moving forwards in time is equivalent to the math of an electron moving backwards in time. This led to a convention in Feynman diagrams.\n\n > The only use this really has is leading to CPT symmetry (e.g., the laws of physics are the same if you invert all charges, parities and direction of time).\n\n > So if someone trapped some anti-proton in a magnetic trap at T=0, held it in the trap for T=1 hr and then released it, mathematically that is the same as trapping a proton (of opposite parity) at T=1, the proton travelling backwards in time to T=0 where it is released and continues to travel backwards in time.\n\n > Granted the universe from our perspective always appears to be moving forwards in time, so the backwards in time solution is generally interpreted as just a mathematical curiosity. Though it could help explain things like how all electrons are identical particles in quantum theory -- you may only need [one electron in the entire universe](_URL_6_)."
]
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"http://www.reddit.com/r/askscience/search?q=antiparticles+time&restrict_sr=on&sort=relevance",
"http://www.reddit.com/user/djimbob",
"http://www.reddit.com/user/Amarkov",
"http://www.reddit.com/user/mindule",
"http://www.reddit.com/r/askscience/comments/gpfyn/if_antiparticles_move_backwards_through_time/c1pb3uj",
"http://www.reddit.com/r/askscience/comments/gpfyn/if_antiparticles_move_backwards_through_time/",
"http://en.wikipedia.org/wiki/One-electron_universe"
]
] |
|
32dzoy
|
why does water not enter my nostrils when i go into the pool?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/32dzoy/eli5_why_does_water_not_enter_my_nostrils_when_i/
|
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"It's sorta like holding the top of a straw when you put the other end in a drink. The air that's there can't go anywhere, so the liquid can't enter. \n\nThat, and I'm always holding my nose shut underwater. "
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1ujlkq
|
why do some english-speakers pronounce the letter 'r' like a 'w'?
|
Edit: Thanks for the responses - enjoyed reading all of the stories that were posted, and thanks to /u/Jontster, /u/Kseeg, /u/bks33691 & /u/maleslp for explaining this to me
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1ujlkq/eli5_why_do_some_englishspeakers_pronounce_the/
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"I did this when I was little, I never properly articulated and the muscles in my mouth did not develop as a consequence. A couple years of daily speech therapy in grade school sorted that out.\n\nI guess I also didn't know how to actually say 'R' words. My mom encouraged me to baby talk and I think that had a lot to do with it too.",
"The formal name for this is [Rhotacism](_URL_0_). It occurs in lots of languages, not just English, but in the opposite way (e.g other letters will turn into r's). In English, it causes the 'r' sound to become more like a 'w'. \n\nThere are some theories as to why it occurs (stress-related, shyness), but in most cases there is no obvious cause.",
"Related story: My son, who was 3yo at the time, was in pre-k. We all know this a developmental time for children. Well, his teacher talked like that. He ended up talking like that. It took us a few years to fix it. \n Does anybody else think that people with this \"problem\" shouldn't be teaching developing minds?",
"My brother has speech apraxia, which basically means a part of his brain that has to do with motor control didn't develop completely. He has had to speech therapy for an hour once a week for the past 14 years. To this day he still pronounces his r's like w's. The problem exists for him because he simply doesn't understand how to make his tongue move to make the 'r' sound. It is a difficult sound to make, but for people who have mastered it, it doesn't seem like it.",
"I only realized after clicking into this thread that you were talking about the speech impediment. Some British accents do this too... Welsh?",
"Hi. Speech-Language Pathologist here. I believe what OP is referring to is called a speech sound disorder. It's one of the more common \"articulation\" disorders found in children when they're developing their sound systems. What (I think) OP is referring to is technically called \"gliding,\" as both [r] and [w] sounds are considered liquids and glides, respectively. The [r] sound (a liquid) is substituted for a glide (the [w] sound), hence the name. [Here](_URL_1_) is a quick rundown on what liquids and glides are (and nasals too if anyone wants extra-credit).\n\nThere are a lot of theories, but essentially we don't really know what causes these sorts of disorders. Many believe it's a neurological \"cross-wiring\" when the sounds are developing in children's brains, others believe it's bad habit, and some would attribute it to other things such as hearing difficulty (if you can't hear the sound well, it's hard to produce - think of a deaf person speaking) or other disorders such as autism spectrum disorders.\n\n[Here](_URL_0_) is a quick guide to speech sound disorders from ASHA, the American Speech-Language Hearing Association for an official, non-ELI5 guide.\n\nEDIT: Just to be clear - if a child has a speech-sound disorder it DOES NOT mean that they have a hearing loss or autism. Often, if a child DOES have a hearing loss or some other type of disorder, a speech-sound disorder can also be found in the child. That is also why when I (or any speech-pathologist should, really) am performing an initial diagnostic on a child, I will make sure hearing is OK and do a family interview for any other speech/language related disorders in the family history (among other things which I won't go into here). It could be a symptom of a larger problem, but it may be isolated - you always want to check.\n\nEDIT 2: Thanks for the gold! I'm no longer a gold virgin! Now, what the heck do I do with this new gilded status?!",
"I am a graduate student studying speech-language pathology, this is called gliding and can occur for a variety of reasons. Most speech errors are not caused by a lack of muscle tone or being stressed/shy, contrary to popular belief. Usually it's just because the correct placement was never learned and speech therapy will teach correct placement and then will include a lot of practice so that the new placement becomes second nature during speech like it is for the rest of us. This particular speech error is extremely common, especially for boys, since r is one of the hardest sounds in our language. In typical developing children, it can take up until the age of 8 to start producing r correctly. Hope this clears things up!",
"I had this aswell. I went to speech therapy for about a year and it went away. I never knew I had it because to me it sounded like I could say my R's ",
"I was in speech therapy for six or seven years trying to correct this (and strangely, pronouncing a normally occurring \"w\" with a \"z.\" Before five or six, I'd pronounce water as \"zaw-tah.\")\n\nI remember being tired of speech therapy in fourth grade and going to be my sessions and being a total dick. The pathologist would ask me questions to try and get me to practice using \"r\" in everyday speech, and I would make a conscious effort to not use it at all (\"I see you have a new shirt. What color is it?\" \"I'd say it's a deep pink.\" \"Would you say it's a red?\" \"I don't believe I would, no.\" \"Now I'm asking you to say that it is red.\" \"I will politely decline. I like to call it deep pink.)",
"I did two years of phonetics at university so I think I can answer clearly, however not so concisely. Sorry!\n\nIf you would go ahead and pronounce the letter \"R\" now you will probably be spreading the back of your tongue so that it's touching your molars. The front of your tongue will be pointing upwards and be very close to the area of your mouth's roof where you would normally articulate the letter \"t\", this area is called the alveolar ridge.\n\nNow try having a go at pronouncing the letter \"r\" without moving your lips. It's just not the same. What we do in the English language to the letter \"r\" is something called labialisation which means we round our lips when pronouncing the sound. Just as we would when pronouncing the letter \"w\".\n\nNow understanding why people pronounce an \"R\" as a \"W\" can have multiple different reasons:\n\n - Second language English speakers do not have the \"R\" sound in their native language so they learn to articulate wrongly as they can't see how it is articulated past the lips.\n\n - Some people who have lisps were there isn't enough tongue thrust may often not be able to get there tongue to reach the alveolar ridge, because of this the labialisation of the lips causes a \"w\" sound.\n\n - Some children learn how to pronounce sounds by simply seeing mouth movement. The \"r\" sound is quite a rare sound in terms of language and is a strange one to articulate correctly. If a child only learns to articulate the labialisation part of the \"r\" sound, it is hard to get out of this habit as an adult. Without being corrected from a young age or without speech therapy, the habit of pronouncing \"R\" as \"W\" sticks throughout adulthood.",
"Is this like what Barry Cripke has ? (Behwee Kwipkee)",
"My little sister had this issue as a child, as a result of a hearing defect that kept her from hearing normally till she was about three. The weird thing with her, though, if that she took nine years of speech therapy, which ended when the therapist informed my parents she spoke completely normal during therapy sessions, but somehow was not able to apply it to daily life. She is now 22, and still speaks like this, and is otherwise completely normal.\n\nThe worst part? Her name is Sarah. ",
"As a child I couldn't make the 'r' sound. I didn't start actually speaking until the age of 3 or 4 so the development of my speech was delayed a little. I always knew I wasn't making the right sound, but I didn't know how to correct it. The 'w' sound was closest I could get to an 'r'. It wasn't until I had a speech teacher who actually showed me with diagrams and models how to position everything that I was able to make an 'r' sound for the first time. Up until 3rd or 4th grade, I couldn't even say my own name right because it had an r in it.",
"I have no formal education in this area, however I had this speech impediment when I was much younger, and went to a speech therapist for this and another issue I had. \n\nThe way I had understood it, it comes from having a hearing issue to some degree, and when you are younger you develop your speech directly from what you hear. As you start forming words, if you hear it a certain way, you will say it that way.\n\nI apologize if I am bending some sub rules, however I firmly believe this to be the way that this impediment comes to fruition.",
"One of the hardest things to say out loud for me is \"Rail Road Tracks\". \n\n\"Whale Woad Twacks\"\n\nApparently it's \"cute\" by everybody's standards. To me it's just frustrating and embarrassing.",
"I was in speech therapy as a kid for what I remember being years. I probably had other speech issues but this was the biggest one. Now as an adult, I have no accent and kind of sound like a TV anchor...I occasionally slip and mess up my words when I'm tired or nervous. ",
"I believe that the R sound is actually really difficult to make. For other languages that don't have it English is a tough language to pick up because of it. Some people just don't fully develop the tongue motions for it. This all coming from my French teacher years ago, but I'm pretty sure he smoked meth so who knows.",
"I knew a girl that talked like that. She thought it was cute to talk like a baby.\n\nIt wasnt.\n\nBut I still had sex with her. Then I weft.",
"The response to mine pretty much nailed it! Young children have to be taught placement in creative ways but they understand. The biggest issue is that they do not usually hear that what they're saying is different/wrong so the first step is usually getting them to hear the difference! To avoid frustrating children the best way to correct an error is to repeat it back to them correctly without drawing anymore attention to it. Example: Child-\"look, there's a wed truck\" Adult-\"you see a red truck? That's awesome!\" No matter how difficult never repeat back the incorrect version because it reinforces it for the child. Very hard when the speech error happens to create very cute phrases haha",
"My little sister who's a sophomore in high school still pronounces things like \"exploded\" as \"uhh-sploded\" or \"ahh-sploded\".\n\nIt's not even worth pointing out to her. She acts like it didn't happen, as if she doesn't know what you're even talking about, or hostile as if you're trying to make fun of her."
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1vdqu1
|
how can i be watching a movie from the 1970's in blu-ray?
|
I was watching Alien [1979] the other day on Blu-ray when I realized, how can this be better than HD quality? Wasn't it filmed before 1979 when HD cameras didn't exist? It still looked good, but is it worth buying over a DVD version? I feel like there had to be a quality cap at the time of filming.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1vdqu1/eli5_how_can_i_be_watching_a_movie_from_the_1970s/
|
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"Old movies were filmed on actual film, which is far higher resolution even than HD. A huge amount of resolution is lost when you down-convert film to any commercial digital format. \n\nTo put Alien on Blu-ray they just had to go back to the original film, or an intermediate high-resolution scan that they might have used when originally making the DVD.",
"It was filmed in HD, so to speak. Alien was filmed on 35mm high quality film, which is better than 1080p. The crappy VCR or early DVD versions are probably not full resolution, and have probably been copied using analogue means several time, losing quality. The blu ray version is probably a high quality generation 2 rip from the film.",
"Celluloid film actually records at higher detail than HD and has since like the 30's. Celluloid film isn't practical, however, for home use, so we have to use digital substitutes, which don't quite record all the detail. It's the same reason why super audiophiles prefer vinyl to CDs. Vinyl contains more information even though it's older. CDs are just more generally practical. ",
"Old 35mm movies had a resolution *way* bigger than what Blu-ray.\n\nRemember, these movies where made to be shown on *really* huge cinema size screens that could be 30 meter or more across.\n\nIf you put up a Blu-ray on that big a screen it wouldn't look good."
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6j2yxn
|
why is sears holding doing so poorly and about to die?
|
Here in SoCal, their stores seem to be doing fairly well. However, it seems that every other week I'm hearing of their impending demise. Any explanation why?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6j2yxn/eli5_why_is_sears_holding_doing_so_poorly_and/
|
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"The simple answer is more and more people are preferring online shopping to brick and mortar stores. Other businesses have already been doing that for years, and they do it better than the ones who are struggling to catch up. Add that to the fact that as far as retail chains go, Sears is a pretty niche market whose niche (homeowners) is growing smaller every year. Time will tell whether or not they actually fold, but I expect significant downsizing at least.",
"Such as the recent bankruptcy of Sears Canada for example?\n\nProbably the number one contributor to Sear's demise would be Eddie Lampert. He is the investment shark who bought the dying KMart in 2005 - which had considerable stock in Sears, which he used to wrest control of Sears properly. Since then he's done nothing but use the assets of the company to maximize his own gains, and done nothing to roll any of those gains into renewing or revitalizing any of the stores, brands etc. \n\nFor example, he sold Craftsman tools - arguably one of the best brands in America. Good quality, lifetime warranty. For $900M.\n\nThis guy is probably one of the best examples of a Gordon Gekko style investor: buy it, squeeze it, leverage it, strip it, sell the carcass. As opposed to Warren Buffett style investors who buy it, nurture it, care, feed and water it and make money off long term value gain and dividends.",
"Sears stores are almost all based in malls, which have had declining traffic for years. Their stores have not really been revamped in forever, and their internal IT systems are horrible. The shopping experience is just unpleasant compared to other big box retailers.\n\nOn top of that add bad management and poor financial decisions."
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5cdnjj
|
what do we know about gravity waves? and what can hope to accomplish should we master harnessing it and manipulating it?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5cdnjj/eli5_what_do_we_know_about_gravity_waves_and_what/
|
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"\nGravity is the weakest of all forces. It takes something the size of the earth, 6 trillion trillion kilograms, just to exert 180 lbs of force on my body. \n\nSo it's difficult to imagine engineering applications for such a small force. Especially when it isn't understood at the quantum level yet.\n \n",
"The most immediate use is observing things we where not able to observe before due to limitations with methods that rely on light, like telescopes or on recieving radio waves. The waves pass by massive clusters of dust and massive objects unobstructed. This could let us in on phenomenon we where unable to see in the past. \n\nIt also gives us more insight on how gravity in general functions, but there is no telling what that could bring. "
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53gv3z
|
how big of a space telescope in relation to the jwst would we need to take surface images of the exo-planet proxima centauri b that are comparable to pictures we have of jupiter etc.
|
^
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/53gv3z/eli5_how_big_of_a_space_telescope_in_relation_to/
|
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"Well, the camera on Juno has a resolution of 15 km per pixel.\n\n_URL_0_\n\nIn order to get the same resolution for proxima Centauri B (4.2 lightyears away), we need an angular resolution of x = 3.78×10^-13 radians.\n\nFor comparison, the James Webb Telescope has an angular resolution of 4.85×10^-7 radians.\n\nNow the size of the telescope, assuming we want to see in visible light, it would need to be approximately 2000 km in diameter.",
"The angular resolution R (in radians) of a telescope can be calculate as R=λ/D, where λ is the wavelength and D is the diameter of the objective (or the primary mirror, in the case of a mirror telescope). Visible light has a wavelength of up to about 800 nm, and a linear resolution of 100 km (enough to broadly make out surface features) at 4 lightyears corresponds to an angular resolution of about 2.6\\*10^-12 radians. Rearranging the formula as D=λ/R, and putting in the values, gives a mirror diameter of a bit over 307 km.\n\nThis is not feasible to build."
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|
3f7t7m
|
Who exaltly was Bill Slim and why is the Burma Campaign known as the forgotten war?
|
I mean I've (very vaguely) heard about the Battles of Imphal and Kohima but I can't find much about the man credited with the victories. Also why is little said about the campaign as a whole? I've been told that Imphal and Kohima were the worst field defeat Japan's ever suffered (which is ironic as I've also been told that Singapore was Britain's worst defeat).
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/3f7t7m/who_exaltly_was_bill_slim_and_why_is_the_burma/
|
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"William 'Bill' Slim was a British General who famously commanded the 14th Army, also known as the 'FBI' (Forgotten Boys in India) in WWII. He's generally considered one of the best, if not the best, British Generals of the war, for his attention to the logistics, training and morale of his troops, as well as his skill as a commander, that allowed the 14th Army to inflict defeat on the Japanese at Imphal and Kohima, and drive the Japanese from Burma in the Meiktila Campaign. \n\nIn general Burma was a forgotten war because it was inconsequential or considered as such by Churchill and the War Cabinet, in comparison to the war in Europe and the Mediterranean. \n\nIf you're looking for an excellent book that covers Burma and Slim, as well as WWII in the Pacific (1944-45), Max Hasting's *Nemesis*, as well as his history of the war, *All Hell Let Loose* are both good places to start. There aren't many titles that I could name, but there has been a good deal written on Slim and the Burma Campaign. If you'd like a more 'audiovisual' source, the British series *The World At War* had a whole episode delegated to the Burma Campaign, called *It's A Lovely Day Tomorrow*.",
"Slim wrote a highly regarded memoir titled Defeat Into Victory which is a very good account of his service in Burma. One of the reasons he is held in high such high regard is that he took command of troops that had suffered a thorough defeat and led them through a long retreat, rebuilt and reorganized them, then led them through some serious positional battles and ultimately led them on what was almost a blitzkrieg into Rangoon. He also made a point of attributing his success to the troops and not to his own brilliance which was rather refreshing. \n One of the more fascinating aspects of the Burma campaign was the action of the Chindits. These were fairly large infantry groups (brigades comprised of battalion columns) that operated behind the Japanese front. Their actual contribution to the campaign is debatable but it is perhaps the most well known part of the Burma war. Their use of air-landing and aerial resupply were quite revolutionary. \n Aside from the Flying Tigers, the events in Burma are not well known in USA so if that is where you are it is no surprise that info is scant. \n In addition to the books recommended by DuxBelisarius I would add \nDawns like Thunder by Alfred Draper \nBurma Victory by David Rooney \nFor a man on the ground aspect of the war I highly recommend \nThe Road Past Mandalay by John Masters \nQuartered Safe Out Here by George MacDonald Fraser \n The Burma Campaign deserves more recognition as it was the bottom of the priority list for troops and supplies yet the troops persevered and won an amazing victory. It was primarily fought by the Indian Army with an assist from African colonial troops under the British, American aviation and even a couple of transport squadrons from Canada. \n \n"
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1pofq7
|
why do i need a strong password? why can't i just use whatever password i like and take on the responsibility if my account is broken in to?
|
Some sites that I use I couldn't care less if broke in to my account (wolframalpha for instance). Yet all these sites have absurd password restrictions. Sometimes it seems that the more I don't care about the password, the more restrictions it has. For instance my university has a requirement that if your password is under 16 characters, it needs an uppercase letter, a number, a symbol, it can't start with a number, and it can't have obvious sequences of letters (vwxyz, qwerty). WHY CAN'T I JUST PICK MY OWN??? Does it really make it that much more secure?
Clarification: I understand why a hard-to-crack password is a good idea. But why not give me the option to make my own hard-to-crack password instead of forcing the same restrictions on everyone (potentially making a password easier to crack as pointed out by /u/Tribler)
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1pofq7/eli5_why_do_i_need_a_strong_password_why_cant_i/
|
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"For a lot of places, getting hacked into isn't just going to affect YOU, it's going to affect other people as well. Basically any account that has email addresses or information or anything could potentially affect all sorts of users, not just yourself.",
"Firstly why do sites force you to have strong passwords? Because of lawyers. You may decide that the security of a particular account is not that important to you, but many other users will not share that point of view.\n\nThus a site which does not take reasonable measures to ensure security faces the prospect of at least severe reputational/brand damage with current and potential users if there is a massive breach of user accounts (step up Adobe this week for example).\n\nNext up the scale of hurt is if the site stores personally identifiable information (PII) which might be used for identity theft or other fraud. At the very least the site operator would have to pay for the affected users to be enrolled in some identity theft monitoring/assistance service at cost. \n\nThird up, if it is sensitive PII (as defined by local data protection laws, e.g. health information, political views, racial/disability data, etc.) then the operator would face fines in the hundreds of K or millions depending on the breach. (Usually bigger fines for sensitive PII, but fines are also possible for non sensitive PII).\n\nFourth up if there is actual loss, then the affected users may sue for compensation and that could be more than the fines depending on the type of breach.\n\nNow you may say that you would be happy to sign away those rights, but some of them (usually pertaining to PII and financial information) are written in to the relevant laws or regulations in such a way as to make that impossible (for your own protection). Also, even if it is legally possible for you to sign those rights away, the courts would often take the view that the balance of power in the relationship is with the site operator and would strike any such provisions out of the agreement if it came to trial. Thus the site operator is facing a risk that they would not sensibly take if they listen to their lawyers.\n\nIt is not surprising that many high profile breaches occur with popular start-up sites in their early days, since they are often run by 12 year olds with millions of someone else's cash to squander, little experience and plenty of hubris. Normally they clean up their act when they have their first major breach and see the prospect of their IPO receding over the horizon.\n\nSecondly, why are long/complex passwords needed? First of all it is important to understand that most hacks are not aimed at a specific individual's account. It is a numbers game and the hackers are looking for the best payoff in terms of time/effort vs. total number of accounts cracked.\n\nSo if you have some people with simple/8 character passwords and others with complex/10 character passwords in the same system, guess which accounts will be the first to be cracked? The only mitigation for this is to make everybody's account meet some minimum standard in terms of difficulty to crack. This will greatly reduce the final number of accounts cracked due to the time and effort required per password.\n\nThe second factor is how these accounts are cracked. Passwords are not stored in plain text by the site (well sometimes they are, and those site operators are very dumb and generally get some or all of the consequences outline above). The password is put through a mathematical process called 'hashing' which basically converts the password from plain text to a different set of characters and numbers.\n\nThe point is that hashing is supposed to be a one way process, i.e. if you put the same password in to your hashing routine, the same hash will come out the other end every time. Conversely a good hashing routine makes it somewhere between very hard and practically impossible to reverse the process and go from the hash back to the original password. When you log in to a site, all it does is hash the password you enter and compare the hash with the one stored in the database to see if it is the same. Security may be further enhanced by 'salting' the hashes, i.e. adding some secret sauce numbers to the hashing process that make the hashes more secure even if you know the hashing routine in use.\n\nThat is also how hackers crack passwords. Usually they will steal a copy of or gain access to the database containing the password hashes. They will then figure out what hashing process the site is using (there are a few commonly used routines and hackers can usually figure out which one is being used even if they don't have access to the site's source code). They will then start feeding passwords in to the same hash routine and compare results with the database until they find matches. This is where the numbers game comes in; the longer they run their cracking software, and the more computing horsepower they have access to, the more passwords will be cracked. Eventually they stop when they have enough for whatever purpose they have in mind.\n\nSo why do long/complex passwords help this process:\n\n- Firstly some older hashing routines are mathematically and/or computationally weak. People have either figured out ways to reverse the hashing process some time after the routine was created, or computing horsepower has reached a point where brute-force cracking is now feasible in hours or days where in years gone by it would have taken weeks, months or years.\n\n- Secondly for some hashing routines used with short (usually 8 character or less) passwords, the hackers can pre-calculate 'rainbow tables' which basically pre-calculate all or many of the possible hashes and allow them to rapidly reverse the hashes with little computation time.\n\n- Thirdly, the software used by hackers will have a vast range of 'dictionary' rules of commonly used passwords that allow the hackers to crack many of the hashes early on. These literally used to be dictionaries of everyday words (in every language you can imagine). As time has gone on, these guys have built databases of non-dictionary words that have been found in previously cracked databases. They also know the common ways passwords are constructed and apply all sorts of substitution rules against the dictionaries. For example \"take a word and try every combination of 1, 2 and 3 digit numbers at the end\" (because you've never changed your password from \"myPassw0rd1\" to \"myPasw0rd2\" have you?) All the common substitutions of letters and numbers, dropping vowels, etc. and even the patterns by which people capitalise passwords are known and used.\n\nUltimately the only defence is to make every user have a password that is computationally hard to crack. That means that every password must have sufficient characters and must contain characters from as large a set as possible. Both these factors increase the computation time required to crack each password massively. Ten years ago an eight character password with letters and numbers would have been pretty secure (unless you had an NSA supercomputer or two handy), these days anyone can rent a few Amazon instances and crack 80-90% of the passwords in a moderately large database in a few days.\n\nAt the current state of the art, a ten character password with numbers, letters and symbols is reasonably secure (again not including government actors in this, just your everyday criminals). Remember though this is a numbers game. A hacker will still crack some percentage of those passwords, but it would be far fewer than an eight character password due to the amount of computation time required.\n\nIn a few years we will probably have to move away from passwords altogether as secure ones will become impractically long to remember.\n\nHope this helps; not a hacker by the way, work in IT security for a bunch of lawyers.",
"I work for an ISP and we inherited an email platform that's over 15 years old.\n\nLooking through the database at the passwords, I was shocked. First off, the passwords weren't encrypted but worse was the standard of the passwords. Hundreds matched the usernames, there were 50 with \"password123\", \"passw0rd\" or just \"password\", dozens set to \"letmein\", multitudes of \"monkey\", \"m0nkey\" and at least five \"hackme\" and thousands that were just a single word or even a string of numbers.\n\nWhat does this mean? it means hundreds upon hundreds of compromised accounts sending out spam, it means we need really incredibly strict spam filters (in and out) otherwise we get blacklisted. So at best, customers get bounce backs when their mail is falsely tagged as spam, at worst, nobody gets to send mail until the blacklist gets lifted.\n\nWe've undertaken a massive project to migrate all this from the ancient legacy platform to a new one which will, eventually, allow us to sort out most of these bad accounts.\n\nSo it's all a massive pain in the arse for you, me, every other user of this platform and anyone unfortunate to receive this spam just because somebody thought that \"banana\" was a suitable password."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
161arp
|
What does it mean when people talk of infinitely dimensioned space (Hilbert space)?
|
askscience
|
http://www.reddit.com/r/askscience/comments/161arp/what_does_it_mean_when_people_talk_of_infinitely/
|
{
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5
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"text": [
"It means that there are an infinite number of degrees of freedom. Alternatively, that no finite subset of the space spans the space. Given any finite collection of vectors, there will be some other vector which is linearly independent of that collection.\n\nHave you read the Wikipedia article on [Hilbert space](_URL_0_)?",
"I think it is useful to think of a vector space in terms of its algebraic properties rather than trying look at it geometry. Well, for any given vector space we can find a basis ( a set of elements that are linearly independent and such that adding any other element to the set makes it dependent) and the dimension of the vector space is said to be the \"size\" of the basis. So for example, if you take the reals, R, then 1 is a basis. R^2, then (1,0),(0,1) are bases. So when we say a vector space is infinite dimension, it just means than the size of the basis is infinite. \n\nWhat are examples of infinite vector spaces? good examples are spaces of functions. For example consider the vector space of polynomials with coefficients in R. Well then a basis for this space is {1,x,x^2 , x^3 ,... ,} and so this space has infinite dimension. \n\nA Hilbert space is a special case of a vector space, it has a couple of additional properties. Firstly, in a hilbert space you have a dot product like you do with R^n (so you have a notion of orthogonality). Secondly, you need the space to have a property called \"completeness\". This is a little bit more technical, but it just says that if you have a sequence which satisfies the Cauchy criterion : _URL_0_ , then the sequence converges (note that this is not always true!) \n\nSo in the mathematical sense, that is what an infinite dimensional Hilbert space. These often have applications in quantum mechanics, though i'm not too familiar with quantum mechanics so perhaps someone else can elaborate more on this connection. "
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Hilbert_space"
],
[
"http://en.wikipedia.org/wiki/Cauchy_sequence"
]
] |
||
5gdnf7
|
when scientists say that your dna can change based on outside influences, what does that mean and how does that work?
|
ELI5: when scientists say that your DNA can change based on outside influences, what does that mean and how does that work?
So for example, does my taste in certain foods, change my DNA? Does my interest in certain women change my DNA?
If I have unprotected sex, thats an outside influence right? So can that effect the changes in my DNA?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5gdnf7/eli5_when_scientists_say_that_your_dna_can_change/
|
{
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"text": [
"im guesssing a decent example could be viruses.\n\nhiv and other retroviruses inject dna/rna into the new host and change it, the virus dna will forever be within the hosts dna.",
"Well mutations happen for all kinds of reasons but I think you are thinking of epigenetics: an epigenetic trait is a \"stably heritable phenotype resulting from changes in a chromosome without alterations in the DNA sequence\" Epigenetic traits can he heritable. \n \nThere is some evidence for example that parental PTSD is being passed down to children but I think it's fair to say this is controversial. \n \n _URL_0_ \n\n_URL_1_",
"Depends on what kind of changes you're talking about. Viruses change your DNA. Radiation changes you DNA.\n\nThere is also what is known as \"epigenetic changes\" which doesn't change the letters of the DNA code but changes what parts are read/expressed. Things like diet and stress seem to influence epigenetic changes, andcan cause effects in the children and grandchildren of a person, such as mortality rates or diabetes in grandchildren of people who went through a severe famine _URL_0_\n\nThis does not mean that *anything* can influence your genes. "
]
}
|
[] |
[] |
[
[],
[
"http://www.nature.com/nrg/journal/v12/n7/full/nrg3028.html",
"http://www.nature.com/npp/journal/v38/n1/full/npp2012185a.html"
],
[
"https://en.wikipedia.org/wiki/Epigenetics#Genomic_imprinting"
]
] |
|
xruip
|
mars time
|
During a NASA press conference today scientist and engineers kept mapping out a mission timeline in reference to local or mars time. what is that?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/xruip/eli5_mars_time/
|
{
"a_id": [
"c5p0ww8"
],
"score": [
7
],
"text": [
"Mars spins slightly slower than the earth. A day on Mars is called a *Sol* and lasts 1^d 0^h 37^m 22.663^s , [NASA adjusts their timekeeping accordingly](_URL_0_)."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Timekeeping_on_Mars"
]
] |
|
4zdcki
|
why do all ants bump their heads whenever they go opposite ways?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4zdcki/eli5_why_do_all_ants_bump_their_heads_whenever/
|
{
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"d6ut7o4",
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],
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2,
5
],
"text": [
"They are tasting/smelling each other, to ensure that they are from the same group. If strangers show up, the ants don't want to let them into the group.",
"Do you mean when they are traveling in opposite directions and touch their antennae together? They're communicating. They aren't \"bumping their heads\" they are sharing information through touch and pheromones about the location of food or predators. Similar to how bees dance to communicate."
]
}
|
[] |
[] |
[
[],
[]
] |
||
75yb2u
|
why are pain meds like vicodin so much different from otc drugs like ibuprofen?
|
Why are stronger pain meds more likely to affect you mentally, and they have warnings against operating machinery, driving, etc, but things like ibuprofen and aspirin don't affect you the same way? Do all pain meds work the same way? Is Vicodin or codeine basically just like taking a ton of ibuprofen?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/75yb2u/eli5why_are_pain_meds_like_vicodin_so_much/
|
{
"a_id": [
"do9u7f1"
],
"score": [
5
],
"text": [
"They affect different chemical receptors. \nVicodin, codiene, morphine and other opiods/opiates have an effect on dopamine production/receptors in the body which are also responsible for \"good\" feelings and can suppress the feelings of pain. Ibuprofen and other usually just effect dilation of blood vessels allowing for swelling to be reduced and the body to help start the healing process.\n\nVicodin and other pain meds usually have ibuprofen in them, but not the other way around."
]
}
|
[] |
[] |
[
[]
] |
|
bnq1wq
|
why is it that when a camera films confetti or snowflakes falling, the quality decreases hugely?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/bnq1wq/eli5_why_is_it_that_when_a_camera_films_confetti/
|
{
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"en85947",
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8,
2
],
"text": [
"[This Tom Scott video](_URL_0_) answers this exact question. \n\nBasically, it's about video compression. Video compression works by storing only (well, mostly) the changes between consecutive frames. If there's a lot of changes between frames, the video is hard to compress, so the compression must sacrifice the video quality.",
"Camera usually films as is, and then when the video is compressed (when you upload it to YouTube for example) you get these compression artifacts, which are the video player's way of filling blank spots on the image"
]
}
|
[] |
[] |
[
[
"https://www.youtube.com/watch?v=r6Rp-uo6HmI"
],
[]
] |
||
3h3rna
|
why do our muscles hurt when we sleep on them weird?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3h3rna/eli5_why_do_our_muscles_hurt_when_we_sleep_on/
|
{
"a_id": [
"cu3zvqh"
],
"score": [
2
],
"text": [
"Because you slept on them weird. They were forced to maintain a position they wouldn't normally maintain, for an extended period of time, with an unusual amount and distribution of weight. Your forearm wasn't meant to have the weight of your torso resting on it for 7-9 hours at a time, so when you do it your forearm basically tells you it hates you and that it's taking some time off."
]
}
|
[] |
[] |
[
[]
] |
||
b5rnyd
|
how are roots able to break through asphalt roads ?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/b5rnyd/eli5_how_are_roots_able_to_break_through_asphalt/
|
{
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4,
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"text": [
"moisture causes cracks which will disrupt soil under the material..if there is a root nearby water will make it grow...",
"The roots lift the asphalt as they grow beneath it. Depending on how big and heavy the asphalt slab is, it can lift the asphalt quite a bit before the asphalt collapses under its own weight.",
"Nature finds a way.\n\nTree roots are full of water channels. Water \"pressure\" (not sure why I did the air quotes, but hey) is very strong. Roots are very strong. They usually grow following the path of least resistance, and sometimes the asphalt is softer than the ground below."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
3ptxys
|
Why do we use microwaves to heat food?
|
Why do we use microwaves to heat food? Why not IR, or UV, which have higher frequencies/more energy?
|
askscience
|
https://www.reddit.com/r/askscience/comments/3ptxys/why_do_we_use_microwaves_to_heat_food/
|
{
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"text": [
"Microwaves penetrate deeply, are easy to produce, and are conveniently harmless.\n\nInfrared ovens exist and we call them toaster ovens. However, it only heats the surface of food because most food is opaque to infrared and it has a very short wavelength. Microwaves are optimized to be absorbed well by food [but not too well](_URL_0_) to produce a more even heating instead of just toasting the surface. The best frequency for heating water by making water molecules rotate is about 10 GHz and ovens run around 2.4 GHz.\n\nAs anyone who has survived eating an unevenly heated Hot Pocket knows, you might even want a frequency that is absorbed even less. \n\nWhat people mean when they say x-rays and UV have more energy is that the wavelength is shorter and individual photons have more energy. An x-ray does not heat through the same mechanism and will basically punch a very small hole in your Hot Pocket and leave a trail of ionized cheese behind it. You do not want holes punched in your DNA and would need to flee the building before activating an x-ray source capable of cooking food.",
"To start, energy per photon is irrelevant. There is absolutely no more benefit to using gamma rays to heat something than there is radio waves. What matters is the power of the radiation, not the energy of each photon. \n\n\nWhen it comes to heating food, there is a number of things to consider. What is the cheapest and most efficient way to generate radiation, how well that radiation can be transferred to the food, how the food reacts to the radiation, and how safe it is for the user.\n\n\nGamma rays, x-rays, and UV are out of the question right off the bat. We don't want dangerous radiation, and we don't want to ionize the food and destroy the molecules in it.\n\n\nIR/visible is used, that's what a heating lamp is and partly what a conventional oven does. The thing about these though, to cook something fast you want all your power going into the food. Traditional elements heat themselves up while emitting light though, like incandescent light bulbs. They are much better suited for traditional oven roles so this heat can be used too. \n\n\nYou could use LEDs or lasers to make mostly light with less heat, but then you have some issues. One, 1000W output from them isn't cheap. Also, the thing would need to be a giant mirrored box, but then you can't see in and even then reflected light will still be absorbed by the lasers/LEDs themselves. As far as cooking goes, the penetration depth of the radiation is pretty poor, so you are either going to burn the outside of the food, or have to cook it slow and let the heat conduct inwards. Also, it won't heat transparent things so you couldn't heat water, it's also going to heat opaque dishes. \n\n\nThen there's radio waves. These are pretty cheap and easy to generate, and we can do high power pretty well with a magnetron. You can contain them in a metal box resonating them inside, you can have a transparent mesh to look in so long as it is smaller than the wavelength, they heat polar molecules like water that are common in food really well via dielectric heating, they don't heat common non-polar dish material like glass or ceramic, they aren't dangerous and molecule destroying ionizing radiation. They seem like a good candidate. \n\n\nWhy 2.4 GHz microwaves specifically out of all radio waves? Well, they can't have too long of wavelength or they won't resonate in a conveniently sized box, also won't heat dielectrics as well. They also can't be too short or they are harder to generate and the holes in a mesh screen would have to be really small. Also, narrowing it down really specifically, they need to be able to be generated without a license. You can't just go creating a bunch of radiation in a band uses for radio, cellphones, airplanes, satellites etc. You need an unlicensed band, and combining that with efficient generation and good dielectric heating considerations we end up with the 2.4 GHz used in microwave ovens. Which is also the one used for WiFi and Bluetooth for the same reason.",
"Historically, just because they worked. Microwave heating was basically discovered by accident. Cavitating magnetrons were being investigated and refined at Bell labs to make radar for WW2, and the heating effect of high power microwaves was noticed and put to good use.\n\nPractically, because higher frequencies will only be absorbed at the surface, and won't heat the food well. Lower frequencies won't fit in the box as well."
]
}
|
[] |
[] |
[
[
"http://www.emu.dk/sites/default/files/physics_of_microwave_oven.pdf"
],
[],
[]
] |
|
5fhqqj
|
the final fantasy video game series
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5fhqqj/eli5_the_final_fantasy_video_game_series/
|
{
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"No, they're not all connected. Most of them are standalone stories, in fact. There are a handful of paired games, where the setting and sometimes characters are the same, but for the most part they're independent of each other.\n\nI think that accounts for a lot of their success, actually. There's always a new story, new characters to get to know, and new game mechanics with (almost) every new release. This keeps the series from getting stale, though they do include some throwback Easter eggs in to keep the lifelong fans entertained even more.\n\nIncidentally, the reason it's called Final Fantasy is that this genre of game had pretty much tanked. Its creator named it Final Fantasy because he intended it to be the last of its kind produced by his studio, based on the market. The first game in the series turned out to be so wildly popular that he stayed in business and carried it on.",
"No, the stories are not connected. Every game in the main series is a sort of reboot with new characters and a new universe.\n\nSome have very different settings. The early ones are medieval style (although with a bit of Sci fi thrown in), then 7 was kind of cyber punk, X was sort of post apocalyptic, XIII was very Sci fi.\n\nThe gameplay can be really different too. The new one is action based where as most of the older ones had turn based style combat.\n\nThe thing that links them are common themes, recurring monsters and other creatures such as rideable birds called chocobos.\n\nSometimes they do make actual sequels, but they don't get a unique roman numeral. For example X had a sequel called X-2."
]
}
|
[] |
[] |
[
[],
[]
] |
||
4crdxw
|
If there's old English, are there older versions of other languages like Spanish, German, Russian, Chinese etc? Did they sound very different as their modern counterparts? And have some languages barely changed or even not at all?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/4crdxw/if_theres_old_english_are_there_older_versions_of/
|
{
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"text": [
"I do not know much about European languages, but I can tell you about the Arabic language. \n\nSince the introduction of the Quran, the Written Arabic Language did not see much change since it gave people a guideline to follow for the language. The Fus-ha, as it is called, remains the same as it was a thousand years ago. The difference between classical Arabic and Modern Arabic comes when talking about the spoken language. There is no set dialect people learn in school, except for the fus-ha which is just standard Arabic. \n\nSpoken language is so different in modern Arabic that a speaker in Morocco is almost unintelligible to an Arabic speaker in Syria or Lebanon. In many Arab countries that were colonized by Europeans tend to use French or English phrases in their speech, for example in Syria we use Merci for thank you and Bonjour for hello instead of Shukran and Marhaba. ",
"I can shed some light on the development of the Czech language, which I am sure will be very helpful! A Czech speaker would definitely understand a compatriot from roughly two hundred years ago rather easily, and could – albeit with some difficulties or with the help of a transcribed text – understand someone from over twice that long ago, give or take a century. \n\nProto-Czech and Early Old Czech spanned a period from about the 10th century to the 13th century and both would be extremely difficult bordering on outright impossible for a present day speaker to understand. Some of the words are similar or familiar in the same way one might recognize a word or two in another Slavic language, however even these would require a transcription in the first place, as both the spelling and the pronunciation were vastly different.\n\nMedieval Czech starts to become less illegible, especially with later texts, but spelling and pronuniciation would pose a major challenge. The orthography reform from the early 1400s attributed to Jan Hus would prove helpful to a 21st century person – before the introduction of diacritics the language might remind the reader of Polish with its use of digraphs (\"cz\") instead of diacritics (\"č\"). Certain transcribed texts could be highly compatible with today's language, compare \"Dřěvo sě listem odievá, slavíček v keřku spievá\" which would be rendered as \"Dřevo se listem odívá, slavíček v keříku zpívá\" today.\n\nThe following centuries would see a present day reader gradually achieve an ever greater understanding of the language, although Habsburg rule and the Germanization policies did make the development of Czech more difficult. Spelling would still be noticeably different from modern Czech, but for example the first complete local translation of the Bible, the Kralice Bible from the late 16th century, is highly comprehensible with a modern transcription (and not unreadable without it either), with lexical differences being perhaps the greatest obstacle. \n\nCompare Revelations 1:8, \"Jáť jsem Alfa i Oméga, totiž počátek i konec, praví Pán, kterýž jest, a kterýž byl, a kterýž přijíti má, ten všemohoucí,\" from the 16th century translation (but a modern transcription) with its 20th century edition, \"Já jsem Alfa i Omega, počátek i konec, praví Pán, který je a který byl a který přichází, ten všemohoucí.\"\n\nFor a perfectly understandable form of Czech without any major obstacles including orthographic ones to someone from our time, look to the culmination of language development during the Czech National Revival in the 18th and 19th centuries. Josef Dobrovský and Josef Jungmann and their works on Czech grammar and vocabulary formed the basis of the Czech language as we know it today, although the structure of the texts can obviously be sometimes rather archaic.\n",
" > If there's old English, are there older versions of other languages like Spanish, German, Russian, Chinese etc?\n\nThe simple answer is **yes**, on all counts. All languages change. They're changing right now. The English (or whatever you speak) is not the same as the English (whatever) of your parents. You might not be aware of the differences, but they're there, and they're small, but they build up over time.\n\nEnglish developed from an earlier stage that we call Middle English. Actually English and Middle English are not set things. These are just arbitrary labels. We call the English after 1066 Middle English, but again since language is constantly in a state of change, there was no one single Middle English. It's just a useful label for us to talk about these.\n\nOld English was the English before 1066. However the further back you go, the more like the other Germanic languages it would have sounded, until eventually it's just Proto-Germanic.\n\nModern Spanish can be brought back to Old Spanish, what was spoken in the first half of the last millennium. Go back further and it's a variety of colloquial Latin, as was French, Romanian and the rest of the Romance languages. \"Romance\" here doesn't mean flowers and a candle-lit dinner, but instead means tied to the Romans.\n\nModern Mandarin is one of a dozen Chinese languages. Cantonese, Hakka, Wu are three others. These developed from what's called Middle Chinese, which was the parent form of the language as spoken around the 7th century and just before. Going back much earlier, you get Old Chinese. Middle Chinese was one path of development that happened from Old Chinese. There were other branches too, but they are now extinct. One such language is Bāshǔ which was originally spoken in the Sichuan Basin but is now long gone, and has been for two millennia.\n\n > Did they sound very different as their modern counterparts?\n\nAbsolutely. Brasilian Portuguese sounds quite different than Latin would have. A speaker of Modern Mandarin wouldn't be able to easily understand Middle Chinese, and a speaker of Middle Chinese would be utterly helpless at trying to make sense of Old Chinese. Same goes for the rest. If we look at a period of a thousand years, you can pretty much guarantee that most spoken languages will be completely unintelligible to modern speakers.\n\nThere are exceptions, such as cases where a community has intentionally changed their language to conform to an older standard. This happens, as people have misguided ideas of language \"purity\" (which doesn't actually exist as a thing), so you'll often find people throughout history arguing to take their language \"back to a purer form\", but again, it's all arbitrary.\n\n > And have some languages barely changed or even not at all?\n\nThere are no natural spoken languages that have barely changed at all. I touched on this above, but I'll reiterate: Any natural spoken language is going to be in a constant state of change, and only through enforcement of older arbitrary standards will there be some slow-down, except often not really because then what you get is a spoken form and a written form which differ, and which people will identify as the same thing, but which actually are not.\n\nLet me know if you want expansion on any of the above points. I just woke up so this this is a little brief.\n\nAlso, if you're interested in this sort of thing, I highly recommend taking a look at an introductory Historical Linguistics text, because that's exactly the sort of thing the subspecialty is about. Any of the following would be a good place to start:\n\n- Hans Henrich Hock, Brian D. Joseph. *Language History, Language Change, and Language Relationship: An Introduction to Historical and Comparative Linguistics*. (1996).\n- Lyle Campbell. *Historical Linguistics: An Introduction.* (2013).\n- Larry Trask & Robert McColl Millar. *Trask's Historical Linguistics.* (2007).\n\n**tl;dr:** Yes. It's all changing all the time.",
" > German\n\nI'd like to single out German for this answer as the answer for German is a little more complicated than for the others. What we know today as Standard German (Hochdeutsch) was historically only a written language which evolved from a kind of artificial dialect of German used by Martin Luther in his translation of the Bible and was based on various dialects of German spoken around Saxony at the time, and has only recently become used as an actual spoken language (and in some parts of Germany, particularly in the South, many people still prefer to speak in their local dialect and have a surprisingly poor command of the standard language). The closest thing there is to 'old German' is what's called [Old High German](_URL_0_), which is the group of German dialects that was ancestral to the dialects spoken in Central Southern Germany, and retain very little intelligibility with modern Hochdeutsch.\n\nFor comparison, here's the Lord's prayer in modern Standard German (which itself seems a little archaic to modern German ears):\n\n\"Vater unser im Himmel,\ngeheiligt werde dein Name;\ndein Reich komme;\ndein Wille geschehe,\nwie im Himmel so auf Erden.\nUnser tägliches Brot gib uns heute.\nUnd vergib uns unsere Schuld,\nwie auch wir vergeben unsern Schuldigern;\nund führe uns nicht in Versuchung,\nsondern erlöse uns von dem Bösen.\"\n\nand in the East Franconian dialect of Old High German:\n\n\"Fater unser, thū thār bist in himile,\nsī geheilagōt thīn namo,\nqueme thīn rīhhi,\nsī thīn uuillo,\nsō her in himile ist, sō sī her in erdu,\nunsar brōt tagalīhhaz gib uns hiutu,\ninti furlāz uns unsara sculdi\nsō uuir furlāzemēs unsarēn sculdīgōn,\ninti ni gileitēst unsih in costunga,\nūzouh arlōsi unsih fon ubile.\"\n\n(if you Babel-fished that literally word-for-word back into modern but very broken German you would get something like \"Vater unser, du der bist im Himmel, sei geheiligt dein Name, komme dein Reich, sei deine Wille, so er im Himmel ist, so sei er in Erde, unser Brot tägliches gib uns heute, und verlass uns unsere Schuld, so wir verlassen unsern Schuldigern, und nicht gleitest uns in (Versuchung?), (sondern?) erlöse uns vom Übel.\")\n\nHowever, you also have Old Frankish which was ancestral to modern-day standard Dutch as well as many of the German dialects spoken in the Rhineland, and Old Low German which was ancestral to most of the dialects spoken in the North of Germany.\n\nI can't speak for the other languages in much detail, but yes, all languages change over time and there will be older versions of all the languages you mentioned. \n"
]
}
|
[] |
[] |
[
[],
[],
[],
[
"https://en.wikipedia.org/wiki/Old_High_German"
]
] |
||
530jfn
|
Why is "speed of light" the only time where a speed is used to quantify a distance? i.e. lightyears
|
askscience
|
https://www.reddit.com/r/askscience/comments/530jfn/why_is_speed_of_light_the_only_time_where_a_speed/
|
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"The speed of light is a speed with units [L/T]. The lightyear has a unit of distance [L] and is defined by the distance traveled by light in one year, thus units come from [L/T][T]=[L].\n\nDue to the coincidence of our Earth's planetary orbit, the distance of lightyears ends up being a really good unit of measure for the distances of stars as the numerical values are neither too big or too small. It's for the same reason we don't use Gigatons as measure of sugar in your kitchen, we use grams or ounces.",
"The speed of light is a universal constant, so that's nice. It's not so much speed that's used to quantify distance as time. After all, light is a constant speed. I have seen time used to quantify distance as well. For example, you might give the \"distance\" in the time it will take you to drive somewhere in a car, and say it's fifteen minutes away or something.",
"It isn't - light-minutes and light-seconds are also used.\n\nIt is also not the only place a rate unit is used with a time unit. For instance, charge capacity of a battery is often specified in amp-hours - amps, like speed, is a measurement of rate - which converts to 3600 Columb. Similarly, you buy energy from your electricity company in units of kilowatt-hours, which are 3.6 megjoules.\n\nThese units are often used where the true units are small, or the compound units more convenient.",
"Because the speed of light is constant.\n\nVery few others things - well, basically nothing - are so constant as the speed of light.\n\nIf, for example, all birds flew at the same speed, we might have come up with a distance called \"crow-days\".\n\nIn fact in the olden days we might have done just that, to an approximation. \"Four days by horse\", for example. These days we like a lot more precision, although you might still tell someone that their destination is \"15 minutes by foot, 2 minutes by car.\"",
"It isn't. People often say thing likes \"My house is about 20 minutes from the beach\" when they mean \"a distance which when traveled by car averages 20 minutes.\" \n\nAlso I have heard things like \"san francisco is an hour and a half from LA\" (by plane)\n\nIn tokyo I will tell people I am 5 mintues from the station. which I mean 5 minutes by walking.\n\nOnce you have a reference speed, or mode of travel which has a (relatively) fixed then using \"time\" to denote \"distance\" makes sense. \n\nSince light is the ultimate reference speed, we can use a unit of time \"years\" to denote distance just as well.\n\nI could say 5-walkingminutes. Or 20-drivingminutes, which would be more accurate in my examples above, but usually people drop those as it is clear from context."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
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||
vkiy7
|
What would happen if a human was hit by an electron near lightspeed?
|
I'm curious what would happen to my body if I was shot with a single electron near lightspeed out of the LHC for example. Would I turn into a red gushing mess? Would I even feel a thing? This has bothered me for quite some time.
|
askscience
|
http://www.reddit.com/r/askscience/comments/vkiy7/what_would_happen_if_a_human_was_hit_by_an/
|
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"The LHC is a proton-proton collier, I'm pretty sure. But let's say we have an electron with the same energy as an LHC proton--that's 7 tera-electron volts (TeV). An electron volt is the energy it takes to move one electron through one volt of potential, so this is like being hit with one electron at 7 teravolts, but that's not really important.\n\n7 TeV is 1.12 microjoules. This is not very much. [It is about seven times the energy of a flying mosquito.](_URL_0_) So, the takeaway is that while that's a LOT of energy, you're still only talking about one electron.\n\nThe more dramatic case would be getting hit with the entire beam. Medical science doesn't exactly know much about this, and I direct you to the following expert speculation: _URL_1_",
"This is routinely done to treat cancer. [link](_URL_0_)",
"Being hit with protons at that speed is much more interesting...\n_URL_0_\n",
"[This guy](_URL_0_) actually took a near-lightspeed proton beam to the head. Surprisingly he lived, despite taking a fatal radiation dose. The beam killed cells in its path, and left him with partial paralysis of his face, hearing loss in one of his ears, as well as siezures."
]
}
|
[] |
[] |
[
[
"http://www.wolframalpha.com/input/?i=7+teraelectronvolts&lk=4",
"http://www.youtube.com/watch?v=lVefgfmFg9o"
],
[
"http://en.wikipedia.org/wiki/External_beam_radiotherapy"
],
[
"http://www.todayifoundout.com/index.php/2010/03/what-happens-when-you-stick-your-head-into-a-particle-accelerator/"
],
[
"http://en.wikipedia.org/wiki/Anatoli_Bugorski"
]
] |
|
ioiao
|
Could someone give me some simple explanations of the theories about what the universe exists in?
|
I figure someone here could do a good job of explaining some of the theories to a non-physicist.
|
askscience
|
http://www.reddit.com/r/askscience/comments/ioiao/could_someone_give_me_some_simple_explanations_of/
|
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"\"What the universe exists in?\" Please clarify what you mean by that.",
"There are none. The universe is all there is (pretty much by definition).",
"We can only observe that which is within the universe. If we can measure it, then it is by definition within our universe. If there is something \"outside\" of our universe, we can't possibly measure it, so it's not a matter science can deal with.",
"If the universe existed within something, that something would also be part of the universe.\n\nThe *observable* universe is basically a local section of universe that exists within a larger expanse of the same.",
"It exists [in a simulation](_URL_0_), of course!",
"The galaxy is on Orion's belt."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
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"http://www.simulation-argument.com/"
],
[]
] |
|
25l8fh
|
how wrestlers can eat a ton of punches and not get knocked out but ufc fighters can get knocked out in a simple punch.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/25l8fh/eli5_how_wrestlers_can_eat_a_ton_of_punches_and/
|
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"text": [
"Professional wrestling is staged. Think of it like a live stunt show. The punches pro wrestlers throw at each other are \"pulled\" punches, which means either the punch doesn't actually connect with the opponent, or the punch isn't really solid.\n\nFor a video example: _URL_0_"
]
}
|
[] |
[] |
[
[
"https://www.youtube.com/watch?v=z5pFRq8WgN0"
]
] |
||
69is5f
|
Are there any books on the Spanish Empire? I can't seem to find any...
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/69is5f/are_there_any_books_on_the_spanish_empire_i_cant/
|
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"text": [
"The AskHistorians Books and Resources list has a [small section on Spain and the Spanish Empire](_URL_0_) that you could check out."
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/wiki/books/europe#wiki_spain_and_the_spanish_empire"
]
] |
||
a3ehqs
|
How does human body excrete radioactive materials once they have been inhaled and/or ingested?
|
For example, if a cigarette smoker would stop smoking today and we only take Po210 and Pb210 (those reside on tobacco) in consideration in the lungs, will the body eventually excrete these materials, some of them, or none at all?
|
askscience
|
https://www.reddit.com/r/askscience/comments/a3ehqs/how_does_human_body_excrete_radioactive_materials/
|
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"Stuff in the lungs isnt excreted, anything foreign, I can tell you ask a smoker of a few things over the years, you will end up coughing out.\n\nI'm not aware if the radioactive elements build up to more risky levels compared to the day to day levels of other like elements in the body.\n\nJust try to avoid russian cigarettes.",
"Radioactive elements get treated by the body much like 'regular' ones, and may end up being utilized in some cases (which is why radioactive jodium can be such a threat: the body stores it in the throat for later user because it doesn't treat it differently than 'healthy' jodium).\n\nSometimes, they disappear in ways regular waste disappears: we exhale them or extrude them in sweat, urine, or feces.\n\nOther times, the element simply decays into something non-radioactive, which may then remain in the body for any amount of time.\n\nI'm not aware of any mechanism for specifically removing radioactive elements, though."
]
}
|
[] |
[] |
[
[],
[]
] |
|
1ackkf
|
"organic" compounds?
|
Oblivious to Chemistry.
Edit; Thanks!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1ackkf/eli5_organic_compounds/
|
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"Organic materials in a strictly chemical sense means: the molecules contain carbon (C) atoms.\n\nThere is some exception to this rule: generally CO2, diamond, graphene and a few others are considered inorganic (that's just the opposite). This has historic reasons and the distinction is a bit arbitrary, though the distinction is useful in chemistry.\n\n[edit] Oh, the reason it's called organic: all living things (that we know of) are made of molecules that contain carbon."
]
}
|
[] |
[] |
[
[]
] |
|
1gtsax
|
To what extent (if any) were Romans involved in the second Greco-Persian war.
|
One of my favorite works of (historical?) fiction is *Soldier in the Mist* by Gene Wolf. The story is presented as the recovered diary of Latro, a Roman mercenary who fought for Xerxes at the Battle of Plataea.
1) How plausible is the idea of a Roman mercenary fighting for the Persians?
2) At one point Latro witnesses Spartans executing the Helots who had been armed and fought for Sparta in the war. Did this occur and if so, why?
3) If anyone else has read this book, I would love to hear comments on the other aspects of the novels historical accuracy.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1gtsax/to_what_extent_if_any_were_romans_involved_in_the/
|
{
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"text": [
"1) It's not very plausible. Herodotos gives a detailed listing of ethnic groups in Xerxes' army, and while there's a lot to doubt in his account, that doesn't mean a historian should make stuff up (obviously it's different for a novelist!). The ethnic groups he lists are all from northern Greece, Asia Minor, and Persia, and some assistance from Phoenicians and Egyptians: none from anywhere to the west.\n\nIn addition, there's very little evidence (if any) of Roman mercenaries ever hiring themselves out to non-Roman powers, at least in the Republican era.\n\nMercenaries of this era were typically pre-existing armies that found themselves unsupported or without anything to do. The idea of a single unaffiliated Roman acting as a mercenary army all by himself is very doubtful.\n\n2) It sounds like it's inspired by an incident in the first few years of the Peloponnesian War (EDIT: i.e. over fifty years later), when there was a secret massacre of 2000 helots who claimed to have given the best service in fighting, under a false promise of freedom, as a way of preventing a helot uprising ([Thuc. 4.80](_URL_0_)).\n\nLakedaimon was in a constant state of war against its helots: the ephors officially declared war every year when taking office. There was an uprising of the Messenian and Spartan helots in 465/4 BCE, and helots certainly did fight in the Persian Wars, but there's no evidence of a massacre of the same kind at that time.\n\n\n3) I haven't read it, so I can't comment, I'm afraid."
]
}
|
[] |
[] |
[
[
"http://www.classicpersuasion.org/pw/thucydides/jthucbk4rv2.htm#4.80"
]
] |
|
7ccv9n
|
In terms of light production vs energy consumption, how much more efficient are modern LEDs than CFLs? What's the limit to increasing efficiency in future years?
|
askscience
|
https://www.reddit.com/r/askscience/comments/7ccv9n/in_terms_of_light_production_vs_energy/
|
{
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"text": [
"Wikipedia article on [luminous efficacy](_URL_0_)\n\n",
"So this is irrelevant for lumens for lighting for human use, but I work with indoor plants and the efficiency of LEDs over CFLs for producing PAR watts (what the plants can eat vs lumens which we see) is crazy high.\n\nAn average CFL bulb is about 20% efficient, meaning if you have a 10w bulb, 8w is radiated as heat at 2w as PAR. An average LED diode is about 25% efficient, not much right? A high end LED COB fixture has efficiency's of up to 65% depending on how much current is run through. This is over 3x as much more usable light for the same power!\n\nFor lumens, a soft run (700mah) COB can output around 180/200lm/w with some high end Quantum Boards (latest \"tech\") reaching over 225l/w"
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Luminous_efficacy"
],
[]
] |
||
79phaf
|
Will a puddle of water stay there forever if the surrounding air humidity is stable at 100% (saturated)?
|
askscience
|
https://www.reddit.com/r/askscience/comments/79phaf/will_a_puddle_of_water_stay_there_forever_if_the/
|
{
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"text": [
"Yes. Water has a certain vapor pressure depending on temperature. When the ambient pressure is greater than the vapor pressure, condensation will occur. If the ambient pressure is lesser, evaporation will occur.\n\nAs long as there is enough water, air pressure in a closed system will tend to exactly the vapor pressure of water, which is 100% humidity. At that point the amount of water being evaporated and condensed is equal and no net change is observed."
]
}
|
[] |
[] |
[
[]
] |
||
5ykloz
|
How can a country have a trade deficit every year without running out money?
|
I'm specifically talking about the US. What is being depleted each year, if any?
|
askscience
|
https://www.reddit.com/r/askscience/comments/5ykloz/how_can_a_country_have_a_trade_deficit_every_year/
|
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"text": [
"Cause money is virtual and isn't linked to something material anymore.\n\nWhen a country is running out of money, it just ask for more on the market and someone is lending them some. But even this money does not exists.\n\nSo basically, countries & people are lending each other money, charging interest and therefor, creating more money ex-nihilo. \n\nRince & repeat.",
"In some cases, trade deficit can be offset by other means of income, for example tourism or remittances. If not, the country has to take loans, in essence betting that in the future it eventually won't have deficit anymore and will be able to pay off the debt.",
"Economist here: These answers are pretty vague and terrible. \n\nThe real reason is a trade deficit is done on a free floating currency. So you never get to zero, you just erode the value of your money over time.\n\nI.e. Each year the trade deficit devalues your currency by 1.5%. You never get to zero or run out of money, as 0.985 x 0.985 added up infinitely never actually reaches zero.\n\nThe US government also has had a lot of irrational investment in it due to the nararive surrounding those investments causing overvaluation so that's dampened some of the devaluation along with economic stimulus in the last few years.\n\nAnyways, Venezuela managed to irrationally run a large trade deficit for years until the market caught on to how broke they were and adjusted the exchange rate rapidly and forcefully:\n\n_URL_0_\n\nYou can run a large trade deficit for a long time before your country's currency suddenly collapses. The US has even more breathing room on this than Venezuela, so don't expect to be waiting in a depression era bread line unless the trade deficit is kept up for many decades.\n\nIt's certainly not helping the US economy though.",
"The more important question is how long can a country produce products with valuable labor, material, and capital resources then send out of country, receiving only paper in return? Ask China. Not forever. We are on the winning side. They send us stuff, we send them promissory notes.",
"Naively, I would expect that if a country imports more goods and services than it exports, then over time a larger proportion of its stocks, bonds and real estate will be owned by foreigners. So the country doesn't \"run out of money\" since the money is coming back to purchase stocks, bonds and real estate. Or is that not true?"
]
}
|
[] |
[] |
[
[],
[],
[
"http://cdn.tradingeconomics.com/charts/venezuela-balance-of-trade.png?s=vnbcbal&v=201702081418t"
],
[],
[]
] |
|
1p3qib
|
how am i able to continue to sing a song, without being conscious i'm doing so, whilst being deep in thought about something else?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1p3qib/eli5_how_am_i_able_to_continue_to_sing_a_song/
|
{
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"I'd assume it's because it's become muscle memory, in the same way as touch typing or any physical other activity works?\n\nI touch type, and I don't consciously think 'I want to press the c button, so I have to put my finger here, and then press.' I just think of what I want to write, without consciously willing my fingers to move.\n\n(IIRC how muscle memory works) The movements needed for you to create the sound have been stored, (as singing is using your throat muscles) as a single action, that can be implemented without much attention.\n"
]
}
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[
[]
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||
4m5bs8
|
why can our bodies develop resistance to harsh viruses such as the flu, but poison ivy still plagues many of us each year?
|
If our bodies can develop antibodies and immunities to rapidly changing viruses such as the flu, why can't we quickly develop a tolerance to a basic plant such as poison ivy which has been around since before mankind?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4m5bs8/eli5_why_can_our_bodies_develop_resistance_to/
|
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"text": [
"Poison Ivy is harsh ironically because of the immune system's reaction, it actually is not harmful, the irritant in poison ivy is called Urushiol, an oil that acts as an allergen, it is basically safe, the body simply overreacts (this is why some people are immune to it, their immune systems react less toward it).\n\nOn the other hand, a virus is a somewhat living thing that reproduces using bodily resources and in the this process, it kills cells. You can die from a virus, while it is almost impossible to die from urushiol (only way I know is inhaling via burning gases, never burn poison ivy, or swallowing it, which causes inflammation in the throat and asphyxiation).\n\nAs pesky as urushiol is, selective pressures have not found it harmful enough to remove the body's allergic reaction to it.",
"Actually, the rash from poison ivy is an allergic reaction. In other words, the very immune system that should be protecting you is panicking about nothing. You cannot become immune because that attempt is what causes the problem in the first place. ",
"Poison Ivy, as indicated by the name, isn't a virus. Your reaction to poison ivy is an allergic/histamine reaction. The body's immune system is normally in the business of protecting us from bacteria, viruses, and other foreign invaders that can make us sick. But when urushiol from the poison ivy plant touches the skin, it instigates an immune response, called dermatitis, to what would otherwise be a harmless substance. Hay fever is another example of this type of response; in the case of hay fever, the immune system overreacts to pollen, or another plant-produced substance.\n\nHere's how the poison ivy response occurs. Urushiol makes its way down through the skin, where it is metabolized, or broken down. Immune cells called T lymphocytes (or T-cells) recognize the urushiol derivatives as a foreign substance, or antigen. They send out inflammatory signals called cytokines, which bring in white blood cells. Under orders from the cytokines, these white blood cells turn into macrophages. The macrophages eat foreign substances, but in doing so they also damage normal tissue, resulting in the skin inflammation that occurs with poison ivy. \n\n",
"Poison Ivy is not actually poisonous. The oily substance on it just happens to be something that causes an allergic reaction in nearly every person. There are those who don't react to poison Ivy at all. The substance is actually perfectly harmless to your skin. But just as with all allergies, that's not what your immune system thinks otherwise and reacts to it. We develop resistance to the flu because our body learns to fight it off. Allergies are our immune system working too well. Allergies can be helped though. Injecting a small highly diluted amount of substances you are allergic to helps to teach your immune system to not treat the substance like a threat. This is called immunotherapy. (I hope I shouldn't have to say that this should be performed by an allergist)\n\nThe same concept could theoretically be applied to poison Ivy. But the costs of immunotherapy outweigh the benefit. It's easier to just avoid the plant all together and deal with the one or two times in your life you get it, rather than stick yourself with a needle ever other day for the rest of your life just so you stop being allergic to it."
]
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[
[],
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41jghz
|
Did German Troops Discharged after WWI Re-Enlist for WWII?
|
The way I understand things, after WWI the armed forces were pretty well liquidated as terms of surrender. So that would leave a lot of former soldiers without jobs. By WWII Germany was mobilizing its forces. Could these former soldiers re-enlist if they so chose - or were they called back to service? How easy/difficult would it be to return to the armed forces after being out of the service for so long?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/41jghz/did_german_troops_discharged_after_wwi_reenlist/
|
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"Hi there. Soldiers who served in WW1 certainly did serve for Germany in WW2. The majority of the interwar (and WW2) officer corps had served initially in WW1. Many of these officers were demobilised due to the limit placed on the German armed forces and later returned when Germany rearmed under the Nazis. However, between the war, many of these men found employment leading Freikorps battalions, although these groups became less important as time went on. Some also drifted into paramilitary groups such as the SA.\n\nAs for enlisted men, many also joined the Freikorps. Most though if they hadn't become officers would have been a bit old for initial deployment. However as the war went on many would be called up as man power became more desperate. Many of these men ended up serving in various battalions, mainly on the home front (eg. As guards of concentration camps and other facilities), although as the war came closer to Germany many did end up seeing action.",
"First of all, Germany had conscription - men were required by law to serve, so there was very little voluntary enlistment - most awaited their conscription orders.\n\nAs /u/Bonnieprince writes, most of the officers' corps had served in ww1. \n\nLower level soldiers consisted mostly of younger classes, and ww1 veterans would be at least 38 years old when the war broke out, and many would be even older. When Germany started to run out of manpower, such men were mobilised for garrison, local defence, technical roles and other non-frontline combat roles. The Volkssturm militia had many ww1 veterans in it when it was called up in October 1944 to help defend Germany."
]
}
|
[] |
[] |
[
[],
[]
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4bfuis
|
what was y2k?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4bfuis/eli5_what_was_y2k/
|
{
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"text": [
"Y2K (or Year 2000) was a huge piece of scare mongering hype in 1999. The popular belief was the at midnight on new years eve all sorts of important computers would crash because they couldn't recognize the year 2000 as an actual date. In the end nothing happened and any systems that could have been effected were patched before there could be an issue.",
"This Eli5 makes me realize I'm getting very, very old. It's almost surreal that so many people alive now wouldn't know that!"
]
}
|
[] |
[] |
[
[],
[]
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||
2b3uvr
|
Time for Fossilization? How long does it take?
|
Considering the footprints found in Romania, figured to be about 36,000 years old. If that person's bones had been found, would they be bones, or would they have been fossilized? How common is it to find a fossil that is still partially bone?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2b3uvr/time_for_fossilization_how_long_does_it_take/
|
{
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"text": [
"The fossilization process begins at the time of an organism's death. Rapid burial under sediments is key for the fossilization process to begin. This prevents decomp from bacteria & protects the carcass from scavengers. \n\nAfter the intial process, it will take thousands of years for a fossil to form. Fossils occur in sedimentary environments. This usually involves lots of water & the deposition of sediments over lengthy amounts of time. \n\nLayer after layer is deposited until the pressure squeezes the water out & lithifies the rock. \n\nSome replacement of bones & teeth may take place. In this process, minerals replace other minerals in the hard parts of an organism. \n\nHard parts are usually the only thing to survive the fossilization process. Soft parts decompose too easily\n\nDepending on the soil, climate and minerals of the area, It takes approx 1.8 million years for bones to become fossilized."
]
}
|
[] |
[] |
[
[]
] |
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3iv4tl
|
How come most Caribbean people are from African descent and not mixed like the rest of the Americas?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/3iv4tl/how_come_most_caribbean_people_are_from_african/
|
{
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"cukh25l"
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"text": [
"Most of us are mixed, though we may not look it. Someone who is 12.5% European and 87.5% African won't necessarily look much like the former. Also, remember that countries like Cuba, the Dominican Republic, and Puerto Rico are Caribbean countries, and people solely of African descent make up a small minority in them. My country, Jamaica, is more visibly black, but I'd still say about half of us are mixed, if not more. There are no good studies on our genetic makeup though. But the reason why the English-speaking islands tend to appear less diverse--Trinidad & Tobago and Guyana (yes, we count Guyana) are exceptions, with more people of Indian descent than of African descent-- is that the proportion of enslaved Africans brought over was greater in proportion to European who settled. That, in addition to the ancestors of most Afro-Caribbean people came to the islands near the end of the slave trade, even though it had been in effect for centuries prior. But before the slave trade was abolished, it was cheaper to work slaves to death within 10 years and buy new ones from Africa than it was to allow them to breed and have to feed all those children. Therefore much of the African population still hasn't been here long enough to mix with the rest of us. The Maroons, a visibly black population, however, have been in Jamaica longer than other black lineages and genetic studies on them have revealed that they are also mixed, most interestingly, with Taino."
]
}
|
[] |
[] |
[
[]
] |
||
7d6l5l
|
why do some people think it's beneficial to "alkalize" the body?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7d6l5l/eli5_why_do_some_people_think_its_beneficial_to/
|
{
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"text": [
"A sufficiently charismatic snake-oil salesman convinced them of it.\n\nMost people don't have much understanding of medicine, biology or science in general. If some huckster starts tossing around fancy sounding words, it's easy to convince them that he's right - especially if it's loosely connected to some actual facts.",
"I think a lot of people think being alkaline makes them feel better, when really it's just act of paying more attention to diet and potentially breathing techniques that do the trick. While there may not be a ton of scientific evidence supporting becoming alkaline there is plenty about diet and breathing/meditation. ",
"The whole alkaline diet or alkaline water thing is pseudo-scientific mumbo jumbo. Your diet has exactly zero effect on the pH of your body, and you wouldn't want it to. Anything you eat must go through the blood stream before it can get to any other part of your body, so we need look no further than the pH of your blood to understand why diet does not affect the pH of the body. \n\nHaemoglobin binds to oxygen in the lungs and then carries it to other tissues to use. The absorption and release of oxygen by red blood cells is affected by pH. If it is too loo low (below 7.35 is called acidosis) your blood won't grab oxygen in the lungs and your tissues will die in minutes. If the pH is to high (above 7.45 is alkylosis) you absorb oxygen in the lungs, but the blood won't release it to your cells and the cells will also die in a few minutes. In order to keep the blood in the very narrow optimal pH range your hypothalmus essentially acts like a pH meter and tells your body to breathe deeper or faster when the pH is too low, which expels extra CO2, which in the blood is in the form of carbonic acid. If the pH is to high the hypothalmus slows your breathing and allows CO2 as carbonic acid to build up. These steps are taken within seconds of the pH being out of the optimal range. Any deviations caused by food you have consumed are corrected immediately. If they weren't, an orange would kill you in minutes."
]
}
|
[] |
[] |
[
[],
[],
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||
9xmb4g
|
at night time, why do windows appear to act as mirrors and lower the visibility through the glass? if you want to see outside the window at night, why is it best to turn out the lights?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9xmb4g/eli5at_night_time_why_do_windows_appear_to_act_as/
|
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"Glass reflects a certain percentage of light passing through it. When you are on the darker side of the window, the light coming through the window is much brighter than the reflection. When you are on the bright side, the reflected light is much brighter than the light coming through the glass.",
"Windows always act like mirrors and lower the visibility through the glass, and it's always better to turn off the lights for a clear view. \n\nThe only difference is that during daytime there's *so much more light* outside than inside that the amount of mirrored light coming from inside is almost entirely imperceptible unless you're intentionally looking for it.\n\nYou can test this right now (or the next time it's day where you live) by turning on your brightest lamp and looking for its reflection in your windows. ",
"5% of photons are reflected back through glass. When they have darkness behind the glass, they show up more than what is behind it. Therefore you see a reflection. ",
"In a way, windows *are* mirrors. They're kind of like see-through double-sided mirrors. \n\nIf it's brighter on *your* side of the window, the reflections are also brighter. So it's harder to see what's on the other side because of all the reflections getting in the way.\n\nAnd backwards, if it's brighter on the other side of the window, it's easier to see what's there because it kind of \"out-shines\" the reflections from your own side.",
"Signal-to-noise ratio.\n\nIf you have high transmission from a bright scene outside, the relatively small reflection from inside is only a few percent of the total signal and you can easily ignore it.\n\nWhen there is almost no light coming in from outside, that small reflection from inside is the strongest signal, so your brain focuses on that instead.",
"Somewhat echoing other responses but:\n\nSuppose glass reflects quarter of the light, and lets the rest through.\n\nWhen it's brighter outside or equal, this means that when you look at the glass, at most a quarter of the light is reflection, and the rest - what is actually outside. You're able to see - perhaps with a bit of glare.\n\nWhen it's much darker outside, say, 10 times, majority of light you see when looking at the window is the reflected bit - making the window act more like a mirror and less like a glass.\n\nWhen you turn off the light, you equalise the amount of light inside and outside - meaning that when you look out, again majority of what you see comes from the outside rather than reflection."
]
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[] |
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||
2zs8v0
|
how is immigration policy determined in the us? why would the us want to limit the number of educated immigrants to the country?
|
American born citizen here. I have a lot of international friends that have to go through a lot of paperwork and trouble just to study and work here. It got me wondering about the policy on immigration in the United States.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2zs8v0/eli5_how_is_immigration_policy_determined_in_the/
|
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"I am a Canadian citizen, and am in no way an expert on immigration, but i believe that the US places limits on immigration because there is limited resources (housing, jobs, healthcare etc.) that exist to serve US-born citizens. \n\nNow imagine that the US relaxes its immigration policies and allows more immigrants in, now there is more competition for those limited resources. This is why immigration policies exist.\n\nIf an immigrant brings skills that are lacking in the US, he should have priority on getting allowed into the US as he can help fill a gap that could not otherwise ve filled by a US citizen. If someone is trying to immigrate to the US and offers skills that many other people offer, that person wouldn't have as good a chance of getting into the country.\n\nThis is why its hard to immigrate into a country. The country has to determine if the people who want to get in will be a benefit to that country and not become a drain on the country's resources. \n",
"The US has the easiest immigration policies -out of any country in the world.- That's because we've always prided ourselves on being a nation that is accepting of immigration. The US accepts 1 *million* legal immigrants EVERY year under a variety of criteria: education, job, sponsorship, family, political refuge, etc. In addition, if you don't meet any of the set criteria, there is a green card 'lottery' accepting approximately another 200,000 per year.\n\nMore than 1 million people per year can put a strain on a country's resources, even one as large as the United States. While the US accepts more immigrants legally *than any other country on earth*, the cap is set so that there are enough resources to go around; not only within the logistical limitations of the immigration program itself, but within wherever the 1 million additional people will study, work, and reside. They will need This is the 'hard' cap, but the 'soft' cap for US immigration also has to take into account, the 6-10 million *illegal* immigrants who sneak in and use the same resources as the legal immigrants.\n\nMany legal immigrants eventually seek citizenship and become US citizens. Welcome aboard!\n\n_URL_0_",
"immigration is complex, but basically policy is decided by congress. The policy prioritizes families first and foremost, keeping children and spouses with immigrant parents/partners (71%). Second and to a much lesser degree are business migrants (21%), and last is cultural diversity (8%)\n\nThe Immigration and Naturalization Act forms the main body, but congress is always doing something here or there that has direct implications on immigration. The actuall enaction of all these changes falls into the hands of different functionaries. Because of security concerns there are many difficulties with getting initial visas and boarder crossing. But once in the country, it is VERY easy.\n\nAlso, generally speaking very easy to enter the US on temporary visas. There are no limits of the number of visa's awarded, and as long as you can wade throught he paperwork required by your particular type of visa, you almost certainly will be awarded the visa (rejection is basically only for people from certain countries or who state certain reasons, or ARE certain people, and those lists are all very small.)\n\nThere are hard caps on categories for long term visas. However, it isn't \"hard.\" Basically with either family or professional sponsorship, you qualify for a green card/permanant visa, and if you have a green card for 5 years, you can apply for citizenship. The catch is, there are very narrow limits on the numbers of green cards issued each year, and those limits are divided by job classification and immigrant status. So, almost ANYONE can come here to work, and while working they are qualified for a green card. BUT they are in line, and it can take many years for them to get in front of that line. More oftne then not, they finish their work in the country, and fail to find another job worth their skills, and so leave before getting a green card. That is what is happening with all the highly skilled people... if you get a 2-4 year high level position, you very well may never see a green card in that time. If you are unable to find another sponser (and no highly trained person is going to get just ANY job for the sole sake of staying in the country) then you lose legal residency status. OF course, it is very easy to survive in the US as an illigal migrant, as long as you pay taxes, you will only have problems when seeking federal services. Most illigal immigrants pay taxes and utilize state services.\n\nThe US congress varies the various limits on immigration categories for a variety of stated reasons, but it isn't a coherent policy and that is why reform is needed.\n\nAs for paperwork on short term visas, it is what it is, but I can say, the US paperwork is comparable to many security oriented countries. The US is also very beuracratic these days. The good news is that there are few hiccups regarding the forms, as long as you aren't from certain places or state certain reasons, you will get in. In reality, you could make up a lot of the information.\n\nThe most important think is the link between them and their sponsor. I've only seen this for academic students going to the US, don't know what it looks like for employeers.\n\nThe US policy has an annual limit of 675k permanant resident migrants not counting immediate family members of citizens, or refugees. only 140k are for professionals, 480 are for family, and make, by far, the highest priority of immigration (this is a stated objective, the goal being to keep families together, healthy, happy, and integrated) The rest of the permanant visas (55k) are part of a lottery program that targets immigrants from contries with low rates of migration into the US, this is in order to promote diveristy.\n\nRefugee green card are not taken from this pool, but are generated seperately by executive order.\n\nSo, every year, over a million people come to the US with a long term visa (not vacation.) and well over 675k of them consider staying. This has been going on for along time, so the backlog is VERY long. Sometimes it is longer than others. Also, because the system is weighted, if you have certain jobs, your chances are super low. Basically, the best way to get in is be family, this will keep your wait in the 2-3 year limit (because they award so many family green cards every year.) Sometimes the wait is really short! I know one acquantance who got a green card 8 months after applying! We were all surprised by that.\n\nIn the case of professionals and people waiting on the cultural diversity lottery, the wait can be oooo so long, too long."
]
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[] |
[] |
[
[],
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"http://www.us-immigration.com/index.html?referrer=adwords&gclid=CjwKEAjwiq-oBRC9gvHCsvDdn2cSJACV3DFRrADPYTsSGCtEhw8og5VQy15_tZiEoCzafDWL0n0LGxoCr3bw_wcB"
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|
9uxmle
|
how can the gop win the senate but lose the house?
|
When people vote don't they vote for their party? Are there people that vote for GOP senators and Dem house members?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9uxmle/eli5_how_can_the_gop_win_the_senate_but_lose_the/
|
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"Some people do vote for candidates individually, not just by party.\n\nBut more importantly, only 1/3 of Senate seats are up for a vote in each 2-year election, while *all* the House seats are up for a vote every 2 years.\n\nAlso, in all but the smallest states, each House seat is voted on by only *some section* of the state, while each Senate seat up for a vote is statewide.",
"Only a third of the senate is up for election each time. And the third that were up for election this year were the same ones who were up for election during Obamas last election. So only 9 republican senators were up for election this year as opposed to over two hundred republican representatives. So even if the democrats were able to win 2/3rd of the senators in this election they would not be able to gain a majority. However that changes drastically in two years. In addition to this the votes are not counted equally when counting for the house or the senate. Each state gets a number of representatives based on the population but all states gets two senators. So if rural voters were republicans and urban voters were democrats then the democrats would take the house and the republicans would take the senate just due to how the votes were tallied.",
"3 Big factors.\n\nEvery House seat was up for grabs, so you can think of it as the House races starting out 0-0. Only 1/3 of Senate seats were up for grabs, so the Republicans started out with a 42-23 lead in the Senate with the other 2/3 of the seats even before the night started.\n\nThe 2nd factor is that Obama in 2012 had \"long coattails\" and brought in a lot of Democrats to weak seats, like Claire McCaskill in Missouri which is pretty red. All those seats, which were up for re-election in 2018 were vulnerable, and some switched back Republican\n\nThe 3rd thing is the way American elections are set up, the Senate really just represents the states, which grossly overrepresents low population, rural interests, and the House more closely represents the population (although it still does a poor job due to gerrymandering and the cap on total seats in the house). For instance, in the Senate, Wyoming and Vermont, which barely have over a 1 million people combined have as much voice in the Senate (with 2 Senators each) as Texas and California, with close to 70 million people. In the House, Wyoming and Vermont have 2 House Seats, and Texas and California have 89 House Seats.",
"The house has loosely proportional representation, which means each state has a number of representatives loosely corresponding to their population: states with many inhabitants get more representatives. A voter has about as much say in the house, regardless of what state he lives in.\n\nIn the senate, on the other hand, each state has two senators regardless of population. That means that in the senate, one Wyoming vote counts as much as about 80 California votes. \n\nSmaller states tend to be rural states, and rural voters tend to be more conservative. Conservative voters tend to vote GOP. ",
"Unlike many other countries we do not vote for parties in the US. We vote for candidates with party affiliation.\n\nAs for how the House and Senate get different results, this is because a House Representative has a 2 year term and a Senator has a 6 year term. There are elections every 2 years, so all members of the House are up for election in those years, while only 1/3 of the Senate is up for election (the terms were intentionally staggered when the country was founded, and as new states were added, the term stagger was maintained. Look up \"classes of US senators\" for more info)\n\nSo there are about 2/3 of the Senate that were not up for election this year. The ones that were, were elected in 2012 (6 years ago) and that was a year that many Democrats were elected (because people were voting for Obama at the same time), whereas the other 2 groups of Senators were elected in 2014 and 2016 which were better years for Republicans."
]
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[],
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1kj04t
|
Was Marcus Aurelius' Meditations published in his lifetime? How was he regarded as a leader, in light of his philosophical bent? What is the best English translation of Meditations?
|
Don't really know how to ask more clearly.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1kj04t/was_marcus_aurelius_meditations_published_in_his/
|
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"The *Meditations* wasn't exactly published in any sense that we think of the word. We honestly don't know what he intended, but it seems unlikely that Marcus treated the text as anything other than his diary or journal (a more honest title may be *To Himself* rather than *Meditations*). In part because of this, we also do not know when it was disseminated, or how. Prevailing theory holds that it was found among his personal effects after his death in 180 CE in modern Vienna, and then copied and recopied through the ages.\n\nMarcus began his reign as a co-emperor, above [Lucius Verus](_URL_2_) as *pontifex maximus*, which demonstrates that Marcus' public authority/prestige, or *auctoritas*, was superior. Veras passed away in 169, leaving Marcus as the sole Emperor responsible for a series of campaigns in the north that came to consume his time in power. However, he is (and likely was) more known for his cultural and intellectual contributions in keeping with Rome's \"beneficial ideology\". These are reforms and decisions he undertook that were very much in keeping with his Stoic philosophy. For example, he endowed professorships in rhetoric, auctioned off Imperial jewelery rather than increase taxes, and seems to have made good appointments to Imperial offices. There was one major civil disturbance during his reign- that of [Avidius Cassius](_URL_3_), a general who attempted to gain control of the eastern half of the Empire in 175. All in all, his reign was mostly harmonious considering the instability that was to come in the next generations.\n\nMy copy, which I think is a good translation, lightly yet usefully annotated, and easy to read is [G.M.A. Grube's](_URL_1_), though someone else may have a better recommendation that comes with more secondary work (it's a little old, but is fairly common from what I know).\n\nSOURCE: [*The Romans: From Village to Empire*](_URL_0_) by Boatwright, et al."
]
}
|
[] |
[] |
[
[
"http://books.google.com/books?id=7SoyXwAACAAJ&dq=The+Romans:+From+Village+to+Empire&hl=en&sa=X&ei=1-4OUtbVNeXV2AXZ6oGIBQ&ved=0CC0Q6AEwAA",
"http://www.amazon.com/The-Meditations-Marcus-Aurelius-Grube/dp/B002JCJRRY",
"http://en.wikipedia.org/wiki/Lucius_Verus",
"http://en.wikipedia.org/wiki/Avidius_Cassius"
]
] |
|
6j3siw
|
what is the loudness war and what side am i on?
|
I hear the term "Loudness War" with respect to recording, but I don't understand what it means. Should I be for or against Loud? What has Loud done to me?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6j3siw/eli5_what_is_the_loudness_war_and_what_side_am_i/
|
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"You aren't quite on a side. The loudness war was an arms race within the music industry of louder and louder albums. You are collateral damage having been forced to listen to albums that inexplicably sacrificed audio quality for volume for ages. ",
"The Loudness War is defined as a trend in recorded music that has gotten generally louder and louder over time. Early records were relatively quiet; later records would record at louder volumes; compact discs set a digital limit that sound engineers would come up against through different compression techniques, and so on.\n\nAs time goes on, it seems the louder music wins out as being the more popular music of the day. Many consumers don't seem to care as much for sound quality as they do for the loudness of the music, as that can grab their attention.\n\nAs for what side you're on? Well, that's a personal question. Do you prefer more dynamic sound with good quality, or is it all Top 40 hits at max volume for you?",
"Music sounds better at high volumes. Partially because you can hear more intricacies and you're more immersed, and partially just because that's how our brains work.\n\nTherefore, over the past few decades, producers have been mastering songs louder and louder, constantly running up against the physical limits of their media (vinyl, cassettes, CDs, digital media). This is so that their songs sound better on the radio without needing the listener to turn up the volume.\n\nBut there's a catch. Mastering a song against the upper limits of its format sacrifices dynamic range and intricacies. There can't be loud parts if the entire song is at max. And frequencies near the limits of our hearing need to be louder to be heard through more accessible frequencies, but those are lost too. \n\nOn the radio, these sacrifices don't matter. It's the radio, it's going to sound bad no matter what, so maxing out loudness makes your song more noticeable to the average listener. But when it comes to listening on a system that doesn't sound like crap (literally anything better than radio), the song will sound better if it's mastered quieter and with more dynamic range.\n\nTurning up the volume on your listening device does not necessarily have the same catches. It depends on the limits of your setup. It makes more sense to leave all the intricacies in the track and let the listener adjust the volume.\n\nExample: _URL_0_",
"any given medium (e.g. an mp3, a record, a web stream) has some maximum value that an instant of sound can have (it's \"amplitude\"); you can't make any instant of sound \"louder\" within that medium past that maximum value.\n\nbut our experience of loudness has more to do with average amplitude over time. one way to increase this is to make all instants have higher amplitude by scaling the signal up, but you can only do this so far before you run into the maximum value for that medium. but there are various techniques to make every instant of the sound closer to the maximum amplitude that the medium can represent (e.g. \"compression\"), but this will change the shape and character of the source signal.\n\nwhat's good about this technique is that people seem to immediately, if momentarily, prefer music that sounds very loud to them - this helps get downloads, purchases, and listeners on the radio.\n\nwhat's bad about this technique is that constantly-very-loud music loses its immediate appeal fairly quickly, and can actually make your ears feel funny/uncomfortable unless its done really well. for example, an action movie that's just one massive explosion would get boring pretty quickly. in addition to making the music boring, it can just make it sound weird and unnatural. another thing that people don't like is that it can make music that hasn't been processed this way sound bizarrely quiet and underwhelming (but some reproduction systems, like the iphone, can try to adjust for this).\n\nbeing on one side or the other is probably a false choice - most people seem to prefer music that has been compressed somewhat, provided that the audio engineer hasn't gone totally berzerk. also, people don't usually listen to massive trap bangers and acoustic folk music in the same playlist, so the massive difference in engineering styles between genres don't usually impact listeners.",
"Basically, at the start of the 90's it was decided that 'louder is better', so when music was recorded, the final master was compressed to make it sound louder.\n\n[Here's an image](_URL_0_) of what the actual waveform would look like if you compared a song mastered in the 80's to the late 90's.\n\nBut, while this made songs appear louder, one thing you'll notice in that image is it leaves no room for dynamic range. Basically, everything is roughly the same volume...so while it gives a louder and arguably more 'full' sound, it leads to the recording sounding flatter. You can't have a quiet, whispered lyric and a build into a big drum or bass hit, because that whispered vocal is going to be the same volume as the bass drum.\n\nThere have also been arguments that overly compressed audio is far more tiring to listen to and can possibly lead to hearing damage. With no variation in volume it has the same effect as listening to loud static.",
"For a concrete example of \"What has loudness done to me?\" take a listen fo Metallica's album *Death Magnetic*. The album was released with an incredibly loud mix that drew criticism for washing out the music, but to make matters worse a far superior mix was released as DLC for the video game *Guitar Hero 3.* [Listen to a side by side here.](_URL_0_) Even the band (notoriously anti piracy) preferred the latter mix and insinuated that they didn't care if you torrented it provided you also bought the album. "
]
}
|
[] |
[] |
[
[],
[],
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"https://youtu.be/7UjQc0dM4H4"
],
[],
[
"http://www.johnsongs.com/wpimages/wpaba8c095_06.png"
],
[
"https://youtu.be/6Nfqpr3ygSg"
]
] |
|
8x3fkn
|
why can my phone with a 4 watt soc play back 1440p video without even getting warm to the touch while my laptop with a much more powerful gpu has to ramp up it's fans and make tons of heat to accomplish the same task.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/8x3fkn/eli5_why_can_my_phone_with_a_4_watt_soc_play_back/
|
{
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"text": [
"Probably because your phone has hardware that can decode the video, while your laptop needs to do it via software.",
"Ah yes, Google’s and Apple’s VP9 beef. Blame Apple and/or Google. Whichever you think is guilty.\n\nGather around kids, let me tell you a story.\n\nI’ll go off the assumption you are referring to a YouTube video here. And I am assuming you are using Chrome, not Safari, as Safari cannot play 1440p YouTube video (we will get into why later).\n\nThe reason is video codecs.\n\nThe issue with video is that video files normally are massive. If we use 1 byte for red green, and blue for each pixel of a 1080p video, then each frame of the video (and there are probably 30 frames in a second) takes up 6 megabytes (3\\*1920*1080). A single second at 30 frames per second would take up 186 megabytes as a result.\n\nWe don’t have the bandwidth nor the storage to handle this. So what do we do?\n\nWe do a little thing called compression.\n\nCompression just uses a bunch of neat tricks to make a video file smaller. For example, if a part of the screen is all the same color, instead of listing the color multiple times, we just list the color once and say “all of these are the same color). \n\nNow for some history.\n\nThere are multiple algorithms for video compression out and about. The most common these days is called h.264, aka the Advanced Video Coding, or AVC. It was established in the late 90s and early 00s. The Moving Picture Experts Group (MPEG) was an organization that was formed in the early 90s to produce such algorithms and this was their latest iteration. \n\nThe issue with MPEG was that they included many different companies who each contributed their patents and findings but refused to give them for free, they started getting greedy. Everyone wants royalties, and a company is formed with the sole purpose of getting everyone to agree to a single set of terms of use. Nonetheless, the algorithm was released with pretty liberal terms of use. \n\nThe year is 2006. Google recently purchased YouTube and MPEG had hints going around of a new video codec algorithm to be released. Google decided to take a different approach, they saw that MPEG was gonna have more issues with parents as each new iteration of their algorithm brought in more knowledge and thus more patents. Instead Google teamed up with a little company called On2 technologies, who designed several codecs to produce the VP8 codec, released in 2008. Eventually google would buy On2 and release the codec for free for anyone to use.\n\nA few years pass, Google is proven right. The new codec MPEG is working on, the High Efficiency Video Codec (HEVC, also called h.265) is turning out to be good but a patent hell (the end consumer doesn’t notice this but companies making operating systems and hardware do). Google iterates on VP8 to produce VP9, a pretty good codec, lagging slightly behind HEVC. But it isn’t a patent he’ll and google says it is good enough. YouTube has become the giant it is today and Google begins to make YouTube use their VP9 codec.\n\nOne of the key things one must understand as well is a little thing called a hardware decoder.\n\nIn computing, there is a principle known as abstractness. One can design a chip that can do one specific thing very very well but can only do that thing, or one can design a chip that can do everything, but slowly and more inefficient in comparison. And this is on a spectrum, CPUs for example do everything but not as well, GPUs are more in the middle, can’t do as much as a CPU but they are very good at doing calculations related to graphics.\n\nThese newer generations of codecs are very computation expensive to use, decoding a video takes a lot of CPU power. So the solution is to design specific parts of the GPU for the sole purpose of decoding video in popular algorithm formats. These are known as hardware decoders, they remove the strain off the CPU to decode, saving both battery and computational power. This is very important in phones, as they don’t often even have the computational power to decode a video with the speed necessary to watch it. So phone processors were the first to implement hardware decoders.\n\nBut there are still benefits to hardware decoders on normal computers and especially laptops, who have limited batteries that shouldn’t be wasted by ramping the processor up whenever a video is playing. So, recently Intel and the other chip companies (AMD and NVIDIA) have all implemented.\n\nAVC was the first hardware decoder to be implemented onto many platforms. Then HEVC and VP9 were also added.\n\nWith many modern devices now supporting VP9 hardware decoding, Google now is trying to switch to ditching AVC and using VP9 only. At this point, most browsers and operating systems have all implemented support for VP9 hardware decoders, except Apple. Despite their hardware (including the iPhone) having hardware decoders for VP9, Apple has refused to implement the software to allow it to be used by apps and browsers. \n\nA codec unsupported by a browser will not play in the browser at all, with or without a hardware decoder. Safari does not support VP9 decoding so YouTube must feed them AVC instead. Chrome on the other hand is Google’s ballpark and they can implement support for VP9 on Mac easily, and they did. But without support from the operating system to give Chrome access to the VP9 hardware decoder, Chrome cannot use it.\n\nGoogle has recently started putting pressure on Apple by refusing to support AVC content for 1440p and 4K videos. Apple as always is silent on the matter and has refused to comment at all, but as a slap to Google, they recently implemented support for HEVC decoding on Mac, but not VP9. \n\nSo the answer to your question is this.\n\nPhones use hardware decoders to make decoding video, the computation intensive task of processing video, more efficient in terms of battery and computation. Computers have this ability as well nowadays. Due to Apple refusing to implement support for a hardware decoder THAT IS FOUND IN THE DEVICES, Chrome has to rely on the CPU to decode VP9 video which YouTube sends to them, making things hot and sweaty.\n\nTL;DR: Google made a new video format. The hardware inside Macs support making processing said video format clean and easy. Google has forced Apple to use this new video format. Apple has refused to implement support for this hardware. Your Mac has to fall back on using the CPU instead of more efficient hardware it already contains.\n\n\nPS: Google began working on VP9’s successor, called VP10. A few years ago. After seeing the collapse of MPEG, many companies and organizations wanted to help Google out. Google then decided to allow their contributions if and only if they released the rights and patents to it and founded the Alliance for Open Media and renamed their codec AV1. Supposedly this codec is slated to release very very soon and should topple HEVC. All major hardware companies have pledged to implement hardware support of AV1 ASAP.\n\nApple has also apparently joined this alliance. "
]
}
|
[] |
[] |
[
[],
[]
] |
||
1rsl1y
|
In our solar system, or any solar system really, does proximity to their sun determine the size of planets?
|
It seems like the planets in our solar system are generally larger the further they are away from the sun. Is this pure chance or does something, such as gravity, play a role in how the planets are ordered? For instance, does having a greater distance from the sun allow the planets to accumulate more mass during formation?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1rsl1y/in_our_solar_system_or_any_solar_system_really/
|
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"In our current standard theory of planetary formation, the planets are most likely formed further out in the protoplanetary disk and migrate inwards after being formed. In our solar system, the small dense rocky planets are closest to our Sun while the giant gas planets are further outside. We think we have a fairly good idea why the planets are distributed like this in our solar system. Roughly speaking, being closer to the Sun heats up the planets more and hence \"heat blasts\" all lighter elements like hydrogen and helium off the planets, leaving only dense, rocky cores. Now, the weird thing is when we look at other planetary systems, we see a sharp distribution of large gas giants, several times the mass of Jupiter, much closer to the star than the Earth-Sun distance. So far we guess that this distribution of gas giants being very close to the main star is because this has (up until recently) been the only way to really discover the planets; the larger the planet and the shorter its orbital radius, the easier it is to detect through the radial velocity method. This doesn't quite explain why the gas giants, several times the mass of Jupiter, can exist so close to the main star though and this is still being hypothesized."
]
}
|
[] |
[] |
[
[]
] |
|
1yjbie
|
FAQ Friday: Have you ever wondered how similar different languages actually are? Find out the answer, and ask your own linguistics questions!
|
We all use language every day, yet how often do we stop and think about how much our languages can vary?
This week on **FAQ Friday** our linguistics panelists are here to answer your questions about the different languages are, and why!
Read about this and more in our [Linguistics FAQ](_URL_0_), and **ask your questions below**!
____
Please remember that [our guidelines still apply](_URL_1_). Thank you!
*Past FAQ Friday posts can be found [here](_URL_2_)*.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1yjbie/faq_friday_have_you_ever_wondered_how_similar/
|
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"text": [
"How much do you find being able to physically make the sounds of a language help with identifying the linguistic history of the same? \n\nAlso, what phonemes do you find to be really interesting and/or unique in some language? What are phonemes in English that are pretty uncommon in other languages? ",
"Does learning more than a single language as a child affect the lifelong ability to learn other languages? If so, how? ",
"I have some questions about language acquisition. It's been difficult to find good studies on these issues, so I hope one of the linguistics experts can help out!\n\n* Are children who learn more than one primary language more likely to be more \"successful\" as adults than those exposed to only one language?\n\n* What are the effects of exposing infants to 3 languages from birth, rather than 1 or 2 languages (which is more common)?\n\n* Do adults who learned more than one language as children tend to go into particular careers more than single-language adults?",
"I've always found it quite interesting how 1, 2, and 3, (as well as other numbers) have a somewhat similar sound. One, two, three May not sound much like uno, dos, tres, but when you start adding other languages, it seems like pattern begin to emerge. Like Hindi's ick, doe, teen (apologize for the spelling). \n\nThese otherwise unrelated languages have some patterns emerging. \n\nAre these just a product of an over active imagination, or did they evolve from the same words into all of these unrelated languages?",
"How did Latin end up breaking into Spanish and Italian overtime?",
"What is the most effective and/or most efficient method of learning a language?",
"A bit of a specialty question. Whence arise the Latin infinitive endings (-are, -ire, -ere)? \n\nI heard they were originally verbal nouns in PIE? Why then do they have no real analog in Greek?",
"Are there any, for lack of better terminology, really far out, or unique languages?\n\nAs an example, consider the fictional language in the Star Trek:TNG episode [Darmok](_URL_0_), where ideas and language is expressed through metaphor and cultural heritage. ",
"Here is a great phylogeny of some European languages - _URL_0_",
"Why is cancer (the disease) associated with crabs in so many languages?",
"Is the idea of an \"Altaic\" language family widely accepted in the field of linguistics?\n\nHow similar are Japanese and Korean and Mongolian?",
"In the film Prometheus [Duh, Spoilers] the android teaches himself how to speak what appears to be the mother Indo-European tongue. This makes me ask several questions.\n\n1. Can we safely say there was one root indo european language, or was it a family of languages?\n\n2. How well do we know the words and grammar of that language? How well can we assume how it sounded and worked?",
"I've noticed that in many languages, the days of the week are using words that symbolize the same things. Where did this start and why did so many languages take it up? \n\n(For example, Monday being 'moon.' I wasn't surprised when I noticed the similarity with romance languages [French being the first language I studied beyond English] but it also applies to Japanese [getsuyoubi - getsu is moon] which isn't a romance language, obviously.)\n",
"Has the internet affected language? How, if so?",
"How come the word mom is similar is so many different languages?",
"It fascinates me how many distinct and seemingly unrelated language families exist among indigenous North Americans. Besides the Inuit, are we able to trace the other distinct indigenous language families to migration patterns from the old world, or determine their origins in some other way?",
"I've heard that Mandarin Chinese is one of the hardest languages for a native English speaker to learn. Why is this? Also, in my own studies of Mandarin I find that the different accents on the same word sound identical to my ears. Why is that, and is there a way to learn to differentiate those accents more easily?",
"Why is there gendered nouns and such in some language while others don't? And how do you decide the gender of an object? For example in German \"die tisch \" why is it female? And \"das buch\" why is a book neuter? "
]
}
|
[] |
[
"http://www.reddit.com/r/askscience/wiki/linguistics",
"http://www.reddit.com/r/askscience/wiki/index#wiki_answering_askscience",
"http://www.reddit.com/r/askscience/search?q=flair%3A%27meta%27&restrict_sr=on&sort=new&t=all"
] |
[
[],
[],
[],
[],
[],
[],
[],
[
"http://en.wikipedia.org/wiki/Darmok"
],
[
"http://language.cs.auckland.ac.nz/what-we-did/"
],
[],
[],
[],
[],
[],
[],
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|
7hwj0i
|
Did the red/black/white color scheme have the same "evil" connotations before the rise and fall of Nazi Germany?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/7hwj0i/did_the_redblackwhite_color_scheme_have_the_same/
|
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"text": [
"From [an earlier answer of mine](_URL_3_)\n\nNo. \n\nThe choice of the Nazi color scheme in their banners was wrapped up in the politics of the German national flag. The flag of the united Germany was the [black-white-red tricolor](_URL_2_) with a [more complicated war flag](_URL_4_) used by some military units such as ships. The imperial tricolor was something of an afterthought for the unified Germany; it originated during the North German Confederation to fulfill a need for a unified ensign for German ships. The flag itself was not a Hohenzollern or Prussian one, although it did incorporate some of their traditional colors. Yet the flag was indelibly associated with Imperial Germany and its lost war. A number of Germans in November 1918 instead opted for the [black-red-gold](_URL_1_) tricolor. These were the colors of the German volunteers in the war against Napoleon and emerged in the post-1815 period as the colors that symbolized a united Germany. The *Paulskirche* parliament and other 1848ers tended to use the black-red-gold over the red flag as the symbol of their movement, seen here quite vividly in the [*Germania*](_URL_6_) portrait that presided over the *Paulskirche* parliament as seen in [this lithograph](_URL_5_). The failure of the 1848 Revolution in Germany though was not the end of black-red-gold and after 1918, it became the new national flag of Germany. Not only was black-red-gold a break from Prussia and the Hohenzollerns, it was also reaching back to a past German democratic tradition. The SPD, Ebert in particular, invested a degree of effort into making 1848 and its black-red-gold as a historical origin for the Weimar Republic. The red flag did not disappear from the Weimar SPD, but was often coeval with the black-red-gold, such as in this [1920 election SPD poster](_URL_0_). \n\nBlack-red-gold though was not an especially popular flag though among the German public, especially among the German right. Most of the German conservatives associated the black-red-gold with betrayal of the front in November 1918 and rebellion. They instead pushed for a restoration of the old imperial flag and some of the far-right *Freikorps* used the battle flag openly. The NSDAP was also among this far right, but also possessed a degree of marketing savvy that stood it above its contemporaries. The NSDAP ensigns used the black-white-red color scheme of the imperial flag, but within a new set of symbols like the swastika. In this way the NSDAP flags bridged the divide between the various right-wing political symbols by repackaging something old-the imperial color scheme- into a new arrangement. \n\nThe Nazis once in power though did little to officially sanction the swastika flag as the new German national flag. While the black-red-gold was out, both the imperial flag and the swastika flag became dual flags of the new German state. This led to various incidents in which exiles and other opponents to Nazism desecrated the swastika flags on visiting German ships. Von Hindenburg's death along with these protests led to the official adaptation of the swastika flag as the sole flag of Germany in 1935. "
]
}
|
[] |
[] |
[
[
"http://www.dhm.de/fileadmin/medien/lemo/images/pli12194_en.jpg",
"https://upload.wikimedia.org/wikipedia/commons/thumb/8/86/Flag_of_Germany_%283-2_aspect_ratio%29.svg/900px-Flag_of_Germany_%283-2_aspect_ratio%29.svg.png",
"https://upload.wikimedia.org/wikipedia/commons/thumb/e/ec/Flag_of_the_German_Empire.svg/330px-Flag_of_the_German_Empire.svg.png",
"https://www.reddit.com/r/AskHistorians/comments/799uie/why_was_the_color_red_so_associated_with_communism/dp12huq/",
"https://upload.wikimedia.org/wikipedia/commons/thumb/e/e2/71-567-B_Flag%2C_Imperial_War_Ensign_German_%2814245345154%29.jpg/1280px-71-567-B_Flag%2C_Imperial_War_Ensign_German_%2814245345154%29.jpg",
"https://upload.wikimedia.org/wikipedia/commons/1/19/Zeitgen%C3%B6ssige_Lithografie_der_Nationalversammlung_in_der_Paulskirche.jpg",
"https://www.zum.de/Faecher/G/BW/Landeskunde/rhein/geschichte/1848/veit.jpg"
]
] |
||
50kfwx
|
Was the original ethnicity/ethnicities behind the Olmec civilization physically notably different from the modern Amerindian populations that now inhabit the same area in any way?
|
I admittedly know far more about later Mesoamerican history than Olmec history, but while I was trying to polish up on research I noticed only superficially that Olmec art seems to show two distinct 'sets' of ethnic type. One is very recognizably Mesoamerican in appearance, such as this [mask](_URL_0_) or the portrait on this [stone](_URL_3_) but others seem purely from a visual look at it to be a different physical type, like the infamous stone [heads](_URL_2_) or this stone [portrait](_URL_1_).
I know there are conspiracy theories that circulated about supposed 'african' origins to the Olmecs and **I don't want to seem as if I am supporting those at all** but-I am curious why so much Olmec art seems to show different physical features than any other major Mesoamerican civilization that follows them. Is it a artistic convention unique to the Olmec? Was there a extinct ethnicity that formed the core of Olmec civilization that was subsumed by more standard Mesoamerican peoples later on?
Lastly, do other, later Mesoamerican peoples have similar facial features in their artwork or are these modern features that I simply haven't noticed?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/50kfwx/was_the_original_ethnicityethnicities_behind_the/
|
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],
"text": [
"I want to preface what I'm about to say by letting you know that we have a section in our FAQ titled [Travel and contact across the Atlantic before Columbus](_URL_1_) that contain other answers regarding the Olmec-African connection.\n\nThat being said, the Olmec heads may look different from their other artwork not because they depict other people from within or outside of Olmec culture, but because of the medium they chose to create that art. The Olmec heads are all carved from large basalt boulders which required a considerable amount of effort to move them from their mountain location in the Sierra de los Tuxtlas down to the coastal areas of Tres Zapotes and San Lorenzo. These boulders are naturally occurring in the mountainous region from where they are collected, but they are not perfectly round or head shaped. \n\nInstead, the Olmec chose boulders that were relatively head shaped on at least one side and it is that side they put the face on. These boulders are very minimally shaped and instead the artist worked with what they had. The decoration and features of the head were carved into the natural surface. Because of this imperfection in the boulders and the lack of further dressing the boulders, the image of the face must be stretched to fit the boulder resulting in features they look a bit distorted from what the people themselves may have actually looked like (Baudez 2012). Baudez does suggest other reasons for the look of the heads and his article is worth reading.\n\nThere are some Olmec heads that show evidence that they were reworked thrones which further constrained how the artist was able to depict the person on the stone (Porter 1989). The alcove in which a figure emerges in the throne came the shape of the inner ear for the San Lorenzo 2 monument, [for example](_URL_2_). Others, like the Cobata head, appear to be unfinished (Hammond 2001). The Cobata head, though, is unique in that it was found on the slopes of the Sierra de los Tuxtlas rather than at Tres Zapotes or San Lorenza which suggest that perhaps part or most of the carving was done before the head was transported to its final destination.\n\nUnfortunately due to preservation conditions in Veracruz, no Olmec human remains have been recovered sufficiently to allow for genetic testing. But it is unlikely that Africans themselves travelled to the Americas prior to 1492.\n\n* [Baudez, Claude-François. \"Beauty and ugliness in Olmec monumental sculpture.\" Journal de la société des américanistes (2012): 7-31.](_URL_0_)\n\n* Hammond, Norman. \"The Cobata colossal head: an unfinished Olmec monument?.\" Antiquity 75.287 (2001): 21-22.\n\n* Porter, James B. \"Olmec Colossal Heads as Recarved Thrones:\" Mutilation,\" Revolution, and Recarving.\" Res: Anthropology and Aesthetics 17/18 (1989): 22-29."
]
}
|
[] |
[
"https://s-media-cache-ak0.pinimg.com/236x/9c/c6/d5/9cc6d5b444e3f8c8f2e91955e007ca25.jpg",
"https://www.sott.net/image/s2/57660/full/olmec1.jpg",
"http://1.bp.blogspot.com/-A10dgVeTMgc/UvcRYSOpCvI/AAAAAAAAKbU/-8sOqvq3Y4Y/s1600/Olmec+4.jpg",
"https://2.bp.blogspot.com/-jNWUXts0Tzs/UnDxkeFmH2I/AAAAAAAAA5E/EXJZdfm9kx8/s1600/Museo+Nacional+de+Antropologia+431.JPG"
] |
[
[
"https://jsa.revues.org/12294",
"https://www.reddit.com/r/AskHistorians/wiki/nativeamerican#wiki_travel_and_contact_across_the_atlantic_before_columbus",
"http://i.imgur.com/z73Aa8m.png"
]
] |
|
30rcvi
|
how does soap and shampoo "clean" you? could you use shampoo like a soap?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/30rcvi/eli5_how_does_soap_and_shampoo_clean_you_could/
|
{
"a_id": [
"cpv29r0",
"cpv92yc"
],
"score": [
3,
4
],
"text": [
"Shampoo is soap. \nSoap encapsulates dirt and greases, making it easier to rinse them off. ",
"It's important to note that soap don't kill bacteria. Soap breaks the surface tension of water and in combination with the rubbing action of you hands, the bacteria gets washed off. Soap created emulsion between water and oil so that oils can be removed form the skin. Your hair needs oils and it's not good for your hair to use soap as it will eventually cause them to become brittle and break. Shampoo is a little more subtle than soap and won't remove all the oils form your hair. However, it won't remove all the oils from your skin either. Use the right tool for the right job."
]
}
|
[] |
[] |
[
[],
[]
] |
||
128w99
|
Are whales, dolphins and other marine life affected by massive ocean storms? Is it hard for a dolphin to get to the surface for air when waves are 20ft high and the ocean is churning?
|
askscience
|
http://www.reddit.com/r/askscience/comments/128w99/are_whales_dolphins_and_other_marine_life/
|
{
"a_id": [
"c6t5d62"
],
"score": [
25
],
"text": [
"Sharks will go deep during a hurricane. Low pressure in the atmosphere above the water will reduce pressure under water, fooling them into thinking they are swimming shallower than they are. \n\n_URL_0_\n\n_URL_1_\n\n"
]
}
|
[] |
[] |
[
[
"http://www.in-fisherman.com/2011/07/12/weather-pattern-pike/",
"http://www.pbo.co.uk/news/405790/new-research-indicates-that-sharks-react-to-air-pressure-changes-predicting-bad-weather"
]
] |
||
oeogw
|
Why hasn't the brain evolved to be able to regenerate itself as easily as skin does? In other words why don't brain cells grow back quickly/at all?
|
askscience
|
http://www.reddit.com/r/askscience/comments/oeogw/why_hasnt_the_brain_evolved_to_be_able_to/
|
{
"a_id": [
"c3gncfa",
"c3gnz3s",
"c3gr3c4"
],
"score": [
11,
10,
4
],
"text": [
"A mature neuron is orders of magnitude more complicated than a skin cell.\n\nIs it as easy to replace an HD television as a lump of concrete the same size?",
"Skins cells are constantly being replaced because they need to be replaced. Skin cells are exposed to the elements constantly, which causes them to fall of the body due to wear and tear. Neurons, especially those in the brain, are more protected, so the need to replace them is limited. In addition, neuron production and connection are highly controlled and organized. If neurons could reproduce at the same rate as skin cells, you would end up with tumors.",
"Ren5311's answer on complexity is definitely a major reason in the difficulty in regenerating the brain. The information within the brain isn't simply the presence of the cells, but the kinds of connections that are made between them.\n\nThat said, the astrocytes and glial cells that surround and support the neurons within the central nervous system also pose a major problem. We find that scar tissue from glial cells usually fills up any space caused by damage to the CNS. This basically creates a giant wall, which prevents any axonal growth.\nThere have been good results, however, in spinal cord (still CNS) injuries where we have used cold to inhibit the growth of the glial cells into the damaged region. Because the glial reproduction is slowed, it does give some of the neurons a bit of a chance to extend axons and recover some connections. We've found that even a small percentage of recovered connections is enough to bring about huge difference in the recovery of function in the affected region. "
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
bte8gv
|
how does the scam in the wolf of wall street work?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/bte8gv/eli5_how_does_the_scam_in_the_wolf_of_wall_street/
|
{
"a_id": [
"eowizsk"
],
"score": [
3
],
"text": [
"The pump and dump scheme? I've only seen the movie once when it first came out, but I'm pretty sure that's what it is. Basically you buy a crapload of low value stocks and create a buzz, causing others to buy which increases the price. Once it hits a certain point you sell all your shares at a profit. Its market manipulation which is illegal. I'm not a lawyer though so I may be wrong."
]
}
|
[] |
[] |
[
[]
] |
||
4d51py
|
what happens if no candidate gets the needed number of delegates for the republican nomination?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4d51py/eli5_what_happens_if_no_candidate_gets_the_needed/
|
{
"a_id": [
"d1nt3di"
],
"score": [
2
],
"text": [
"They vote again until one does, it is a fairly simple process. It is called a contested convention."
]
}
|
[] |
[] |
[
[]
] |
||
46o5bo
|
why would a gravitational wave travel at the same speed as light?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/46o5bo/eli5why_would_a_gravitational_wave_travel_at_the/
|
{
"a_id": [
"d06mzyd"
],
"score": [
5
],
"text": [
"Calling it the speed of light is sort of a misnomer, really. Instead, there's a speed of causality in the universe that no information can travel faster than. So light travels at the speed of causality, and so do gravitational waves. \n\nFor more information, watch [this](_URL_0_) great video from PBS Space Time. He explains the speed of causality really well."
]
}
|
[] |
[] |
[
[
"https://www.youtube.com/watch?v=msVuCEs8Ydo"
]
] |
||
4l86k6
|
how does this phone holder for your car not break your phone?
|
Hello Reddit! I want to know how [this phone holder](_URL_0_) works without breaking my phone.
It essentially works by putting a metal plate on the back of my phone and then having a car mounted magnet hold up my phone via magnetic force but I have always heard that you should not put magnets near electronics so how does this work without breaking anything?
Also if I put credit cards into my phone case and I have them sitting between the metal plate and the magnet will it break them? I have heard the same thing about magnets and credit cards too.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4l86k6/eli5_how_does_this_phone_holder_for_your_car_not/
|
{
"a_id": [
"d3l4sn8"
],
"score": [
5
],
"text": [
"There are two electronics components that are sensitive to magnets: cathode ray tube (CRT) screens and hard drives. Your phone does not have either of those- it has an LED or LCD screen instead of a CRT and uses flash memory instead of a hard drive. \n\nWith credit cards, the magnetic strip will get messed up with a strong magnet, but the chip that more places are switching to using (and pretty much everyone outside the US has fully switched to) will not be impacted by a magnet. The magnet on the case probably isn't strong enough to mess up the credit cards, especially with the metal plate between the cards and the magnet, but I'd probably avoid it just to be safe."
]
}
|
[] |
[
"http://www.amazon.com/WizGear-Universal-Magnetic-Swift-SnapTM-Technology/dp/B00PGJWYJ0?ie=UTF8&keywords=phone%20mount%20car&qid=1464305951&ref_=sr_1_1&sr=8-1"
] |
[
[]
] |
|
kucuy
|
Ask Science: virtual images vs real images in optics
|
So I've already read through the comments [here](_URL_0_) but I still don't truly understand virtual images versus real images.
I get that virtual images are made from rays that diverge. But why can't a camera see them?
A camera is just a lens with a screen (CCD, film, etc). Your eye is just a lens with a screen (retina). So why can you see something a camera can't capture? What is fundamentally different about these two setups?
(PS feel free to use jargon in your response if it makes it easier - I'm actually in a microscopy class right now)
|
askscience
|
http://www.reddit.com/r/askscience/comments/kucuy/ask_science_virtual_images_vs_real_images_in/
|
{
"a_id": [
"c2nafpi",
"c2nafpi"
],
"score": [
4,
4
],
"text": [
" > But why can't a camera see them?\n\nA camera can see them just fine. Take a picture of yourself in the mirror. Congratulations! You just photographed a virtual image.\n\nYou may be thinking of the fact that you can't focus a virtual image on a screen. That is to say, there is no position where you could place a flat screen and have the image appear on it. Or, to put it another way, it's impossible to take a picture if your camera has no lens -- whereas a real image has a focal point where you could place a lens-less camera and get the picture. \n\nBut that does not preclude you from using a lens or mirror to create a real image of a virtual image.",
" > But why can't a camera see them?\n\nA camera can see them just fine. Take a picture of yourself in the mirror. Congratulations! You just photographed a virtual image.\n\nYou may be thinking of the fact that you can't focus a virtual image on a screen. That is to say, there is no position where you could place a flat screen and have the image appear on it. Or, to put it another way, it's impossible to take a picture if your camera has no lens -- whereas a real image has a focal point where you could place a lens-less camera and get the picture. \n\nBut that does not preclude you from using a lens or mirror to create a real image of a virtual image."
]
}
|
[] |
[
"http://www.reddit.com/r/askscience/comments/hgvou/i_cant_seem_to_understand_what_a_virtual_image_is/"
] |
[
[],
[]
] |
|
27mef8
|
how do travel agents get paid?
|
ELI5: My fiance and I are dealing with a travel agent to plan our wedding and I was wondering how they make money?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/27mef8/eli5_how_do_travel_agents_get_paid/
|
{
"a_id": [
"ci277jw",
"ci27gj9"
],
"score": [
3,
3
],
"text": [
"Aren't you paying this travel agent? \n \nI'm surprised that there still are travel agents. I remember seeing travel agencies in strip malls when i was a little kid but I haven't seen one in years.\n \n",
"Travel agents generally collect directly from you when you book with them as part of the fee for the whole package. \n\nWebsites that offer the airline/hotel/car rental packages are basically functioning like travel agents would have in days past."
]
}
|
[] |
[] |
[
[],
[]
] |
|
2pmapm
|
How does a light bulb light up a whole room?
|
I know the bulb must disperse photons but...
1) What part of the bulb allows the electrical energy it receives to release these photons?
2) How is the movement of these photons measured once they are "created" by the bulb?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2pmapm/how_does_a_light_bulb_light_up_a_whole_room/
|
{
"a_id": [
"cmy0dnw"
],
"score": [
14
],
"text": [
"For an incandescent bulb, electricity runs through a filament in the middle causing it to heat up through simple Joule heating (essentially, the electrons in the electrical current smash into the atoms in the wire and lose some of their energy to heat). The filament heats up enough that it emits visible light through thermal emission. The light is therefore coming right from the filament\n\nFor a fluorescent bulb, electricity runs through gas in the tube, causing it to partially ionize (electrons get ripped off the atoms of the gas). When the ions and electrons recombine, they emit their energy as ultraviolet light. The UV light hits a fluorescent coating on the glass tube which converts the UV light to visible light. The visible light is therefore coming directly from the coating on the glass surface. In fluorescent materials, an electron absorbs UV light and is excited to a higher energy state, and then it de-excites back down in a two step process, where visible light is emitted in one of the steps.\n\nFor an LED bulb, electricity creates electron-hole pairs in a semiconductor. When the electron transitions down and recombines with a hole, it emits visible light. The light is therefore coming from the little semiconductor chips in the bulb.\n\nThe visible light created by each of these bulbs spreads out in all directions until it hits your wall, your chair, etc. Some of the light is absorbed, but some is scattered in all directions. Some of the light that hits objects gets scattered into your eye. Inside your eye, the back of your eye is covered with little cells with a light sensitive molecule. When this molecule absorbs light, it changes shape and triggers a biochemical reaction which triggers an electrical impulse that travels along nerves to your brain where you perceive the reception of light."
]
}
|
[] |
[] |
[
[]
] |
|
1c0tjy
|
What's the smallest possible number of fundamental units, and what would they be?
|
I know the SI system has 7, but I was thinking and realized that distance and time are actually the same, aren't they? And a mole is just a numerical multiplier, right? So, how few units could you end up with?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1c0tjy/whats_the_smallest_possible_number_of_fundamental/
|
{
"a_id": [
"c9c3e30"
],
"score": [
3
],
"text": [
"In principle, you can have only one unit. \n\nThe idea is that some fundamental constants are actually just proportionality factors, so you can just set them as 1. These are the speed of light, Planck's constant and Boltzmann constant. So distance and time are the same, which are inverse mass, energy, frequency and temperature. Of course you still need to express these in terms of a length/mass scale, and if you agree on one length scale (as cosmologists like to use, Planck length), then you can reduce your units to 0."
]
}
|
[] |
[] |
[
[]
] |
|
1vri4l
|
why do many southeast asian countries have such harsh drug laws?
|
Mandatory capital punishment for trafficking seems excessive. Is there a historical basis for why this part of the world is so hard on drugs?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1vri4l/eli5_why_do_many_southeast_asian_countries_have/
|
{
"a_id": [
"cev3mjb"
],
"score": [
2
],
"text": [
"These countries are are trying to improve their economic standing. They don't want people to steal to get their high, or become homeless, or jobless. They also don't want the children of he area to get addicted to any drugs. That's where most of the anti-drug sentiment comes from. They see it as if your trafficking/selling drugs, you might sell to a child which would ruin their lives, in essence you would kill his life though he would still be living. So basically their getting the death sentence for ruining other peoples life's."
]
}
|
[] |
[] |
[
[]
] |
|
1sv9n8
|
We can create in vitro meat. Is there any research to create in vitro wood?
|
There are lots of discussion about how we can reduce human impact on the nature. One important point is if we will soon be able to create in vitro meat in commercial quantity. However, maintaining flora on the planet can be of the same importance. Are there any scientific research done to synthetize for example woods? I understand that there are lots of substitute materials, but even considering them, still lots of houses / furnitures / paper etc. are made of woods.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1sv9n8/we_can_create_in_vitro_meat_is_there_any_research/
|
{
"a_id": [
"ce1p805"
],
"score": [
7
],
"text": [
"Never heard of anyone trying to grow in vitro wood. It's possible that someone is doing it somewhere but I doubt there's much money in such a prospect.\n\nThe reason in vitro meat is desirable is because mass animal farming is highly destructive to the environment. Mass tree farming is not nearly so. Done properly it would likely even be somewhat beneficial.\n\nEven when trees aren't farmed and instead are harvested from the wild there are ways to minimize impact. Taking only certain trees and replanting with seedlings can help to keep a forest going strong.\n\nAdditionally, I see many problems with in vitro wood that meat wouldn't have. Meat is alive, while much of the wood in a tree is effectively dead. Its strength comes from the layers of living tissue building on top of the dead layers and dying. Ask anyone who works with wood, faster growing trees generally have weaker wood. Wood grown in a dish would most likely be even weaker."
]
}
|
[] |
[] |
[
[]
] |
|
2rv6tx
|
why do people squeeze lotion onto the back of their hand?
|
I consistently see people squeeze lotion out onto the back of their hand, even if they then proceed to apply it to their whole hand. I don't see this with hand sanitiser, soap, or anything else. Just lotion. Why do people do this?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2rv6tx/eli5_why_do_people_squeeze_lotion_onto_the_back/
|
{
"a_id": [
"cnjjqy7",
"cnjjsfq"
],
"score": [
2,
2
],
"text": [
"The back of your hand gets dry and cracks the most, and needs as much lotion as possible. After they make sure the back is well covered the rest is dispersed evenly to the rest if the hands. ",
"I would imagine its also so the front of their hand doesn't get an overly saturated amount but rather an even coat.\n"
]
}
|
[] |
[] |
[
[],
[]
] |
|
63exoa
|
How did the Teutonic Order justify fighting Catholic Lithuania+Poland?
|
As I understand it, they were supposed to be there to conquer Pagan Lithuania. Then Lithuania converted to Catholicism. So the Knights... stayed around and tried to mess with the Lithuanians, until eventually they fought a massive battle against the combined Lithuanians and Polish. But how did they justify this? As an order of militant monks, didn't it rather go against the whole point of them? And how/why were they still getting recruits after the pagan "threat" was over?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/63exoa/how_did_the_teutonic_order_justify_fighting/
|
{
"a_id": [
"dfv5zwd"
],
"score": [
2
],
"text": [
"Ok so there is a lot going on with this question. \n\nLithuania was a pagan state until the Union of Krew(v)o in 1385-1386.\n\nThe knights that you refer to in your question would be the Teutonic Order, but by the time of the Union of Krewo they would have expanded and absorbed smaller regional orders as well. The most prominent one (and possibly only one) was the Brothers Militia of Christ in Livonia called the Sword Brothers today by most historians.\n\nStarting from around 1200 AD there was conflict between Germanics, Danes and Rus, Lithuanians and various tribal groups in the area which became Prussia and Livonia. The conflict in these regions ended essentially with the events of the St.Geroge's Night Uprising in 1350 AD (in Livonia). \n\nAfter this and the above mentioned union of krewo the knight order sort of morphed into a secular power, though I would argue it had always functioned like that. Once the knights were a primarily secular power then they acted like one and engaged in warring for the sake of territory ect. \n\nThe second battle you refer to is the Battle of Grunwald in 1410 which saw the now Polish-Lithuanian Commonwealth defeat the order. \n\nAs to why the order kept getting recruits second and third sons of nobles made up a good chunk of their ranks. \n\nLooking at catholic teaching there is no way to justify violence against other catholics for political sake. There is also little justification to convert people by the sword, which is why Poland in 966 AD was baptised without much violence and why in Livonia tribes who accepted the catholic faith without violence were treated well and not hurt for religious reasons. \n\nAs for sources I will provide easier to access ones (ie not routledge/brill, but i can provide them if you want them)\n\nRead the following\n\nNorman Davies God's Playground a History of Poland (volume 1 is the relevant one)\n\nHenry's Chronicle of Livonia (translated by James A. Brundage) Colombia University Press 2003 \n\nAleksander Pluskowski Archaeology of the Prussian Crusade \n\n(this is a more expensive book) but Anti Selart Livonia Rus and the Baltic Crusades in the 13th Century Brill 2015\n\nAlso try more general sources such as William Urban's History of the Teutonic Knights or God's War by Christopher Tyerman. Lastly you could also look into catholic teachings but this is not required for more general level answers.\n\nedit and Stone's more recent volume on the Polish-Lithuanian Commonwealth (sometimes Davies is a little too Polish centric). "
]
}
|
[] |
[] |
[
[]
] |
|
9ap5gt
|
why does driving feel smoother in the drivers seat?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/9ap5gt/eli5_why_does_driving_feel_smoother_in_the/
|
{
"a_id": [
"e4x08y1"
],
"score": [
9
],
"text": [
"When you know what will happen, your body prepares for it.\n\nHard left, you know exactly when it will happen.\nAceleration, deceleration are the same, you prepare for acceleration when you press gas pedal.\n\nPassengers are surprised when something happens, and their body doesn't react.\n\nLike in football, if someone slams against you and you expect it, you might even not even fall down. But someone surprise slamming into you while you are relaxed and standing on a street not expecting it, you will hit the ground so hard."
]
}
|
[] |
[] |
[
[]
] |
||
1p0r0l
|
The 3 divisibility rule is if you add up the digits of any number, and the sum you get is divisible why 3, then the larger number is too. Why is this?
|
askscience
|
http://www.reddit.com/r/askscience/comments/1p0r0l/the_3_divisibility_rule_is_if_you_add_up_the/
|
{
"a_id": [
"ccxkgkw",
"ccxkjyy",
"ccxl704"
],
"score": [
4,
35,
3
],
"text": [
"First of all, observe the following things:\n\n * If a number A is divisible by 3, and number B is divisible by 3, then A + B is divisible by 3\n * If a number A is *not* divisible by 3, and number B is divisible by 3, then A + B is *not* divisible by 3\n * For any number A, 9 * A is always divisible by 3\n\nThen, look at a two-digit number \"XY\". The value of this number is 10 * X + Y. The sum of its digits is X + Y.\n\nIf you take the sum of digits (X + Y) and add 9 * X, you get 10 * X + Y. That is: you take the sum of digits, add something that is divisible by 3, and get the number itself. Therefore, a two-digit number is divisible by 3 exactly when the sum of its digits is divisible by 3.\n\nFor example: (2 + 5) + 9 * 2 = 25\n\nLook at a three-digit number \"XYZ\". Its value is 100 * X + 10 * Y + Z. The sum of digits is X + Y + Z.\n\nIf you take the sum of digits (X + Y + Z) and add 9 * (11 * X + Y), you get 100 * X + 10 * Y + Z. That is: you take the sum of digits, add something that is divisible by 3, and get the number itself. Therefore, a three-digit number is divisible by 3 exactly when the sum of its digits is divisible by 3.\n\nFor example: (2 + 5 + 7) + 9 * (22 + 5) = 257.\n\nEtc etc for numbers with more digits.",
"Suppose we have a number that, in decimal representation, has the digits ABCD. This means 1000A+100B+10C+D. We can re-write this as\nA+999A + B + 99B + C + 9C + D. The terms 999A, 99B, and 9C are all multiples of three.\n\nThus\n\nABCD = (multiple of 3) + A + B + C + D\n\nConsequently, ABCD will be a multiple of three if A+B+C+D is.\n\nObviously, this generalizes if we have more than four digits, since any power of 10 is a 1 plus a multiple of 3.",
"Lets say N is a three digit number with base 10 representation abc.\n\nN = 100a + 10b + c\n\nTo test whether something is divisible by 3, you divide it by 3 and see if the remainder is 0.\n\nif remainder(N/3) = 0, then N is divisible by 3.\n\nN/3 = (100a+10b+c)/3\nN/3 = 100a/3 + 10b/3 + c/3\n\n==============================\n\n\nNow heres the unique thing about dividing by 3:\n\nLets look at the first division, 100a/3. \n\nIf remainder(a/3) = 1, remainder(100a/3) = 1. \n\nIf remainder(a/3) = 2, remainder(100a/3) = 2. \n\nIf remainder(a/3) = 3, remainder(100a/3) = 0\n\nYou can prove this to yourself by using different values of a (ie 1, 2, 3). This property is true whether you multiply a by 100, 1000, or any power of 10. This is because the remainder of any power of 10 divided by 3 is 1 (because 9, 999, 99999, etc is always divisible by 3).\n\n======================\n\nSo considering that:\n\nremainder(N/3) = remainder(100a/3) + remainder(10b/3) + remainder(c/3)\nremainder(N/3) = remainder(a/3) + remainder(b/3) + remainder(c/3)\nremainder(N/3) = remainder(a/3+b/3+c/3)\nremainder(N/3) = remainder((a+b+c)/3)\n\nNote: Remainders are summable. remainder(s/3) + remainder(y/3) = remainder(s/3+y/3). You can test this out with various numbers and it's pretty easy to prove to yourself.\n\nSo if a+b+c is divisible by 3, N is divisible by 3. Hopefully that wasn't too confusing."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
7qr77r
|
what prevents blood from flowing backwards into an iv bag?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7qr77r/eli5_what_prevents_blood_from_flowing_backwards/
|
{
"a_id": [
"dsra0hw",
"dsra620"
],
"score": [
5,
24
],
"text": [
" The fact that the needle is facing away from the direction of the flow, and gravity. Put the bag below your heart, and you'll see blood go back up the tubing into the bag. ",
"Gravity. \n\nThe IV bag hangs above the patient and the solution flows down the IV line. This pressure pushes the IV solution into vein which prevents blood from flowing into the tube. "
]
}
|
[] |
[] |
[
[],
[]
] |
||
7opxjr
|
how is it that breasts get slightly bigger then slightly smaller again during 'that time of the month'
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7opxjr/eli5_how_is_it_that_breasts_get_slightly_bigger/
|
{
"a_id": [
"dsbe5wk"
],
"score": [
4
],
"text": [
"Progesterone and prolactin are released during your period, which causes breast tissue to swell and milk glands to increase in size. Your body will also retain water which may contribute. "
]
}
|
[] |
[] |
[
[]
] |
||
36zbsw
|
Will the continued acidification of our oceans by CO2 absorption have a notable impact on Earth's oxygen supply? (by causing environmental changes for plankton)
|
I found [this](_URL_0_) article on the subject from Princeton University, and they say that the reduction in available elements due to lower pH is balanced out by less energy expenditure collecting carbon.
Has this been further concluded? Is there any new research or data on the subject? It struck me that we might be screwing ourselves over even further by messing with our major oxygen factory, which scared the shit out of me.
No flair because I'm not sure which one to pick.
|
askscience
|
http://www.reddit.com/r/askscience/comments/36zbsw/will_the_continued_acidification_of_our_oceans_by/
|
{
"a_id": [
"criihyi"
],
"score": [
7
],
"text": [
"Are you referring to atmospheric oxygen, oceanic oxygen, or both? Also, are you asking about ocean acidification effects on primary productivity and photosynthesis in the ocean?\nAtmospheric oxygen has indeed been going down as a result of fossil fuel burning. If you're interested in how atmospheric oxygen levels have acted for the past 25 years or so, have a look at the data from Ralph Keeling's group at Scripps (plots helpfully shown [here](_URL_0_)). \n\nBut to answer your last question, the perturbations in atmospheric oxygen aren't enough to affect humans. Changes in oceanic oxygen could potentially [affect marine habitats and ecosystems](_URL_2_) though, and the combination of warming, acidification, and deoxygenation in the ocean will certainly [change marine biogeochemical cycles](_URL_1_)"
]
}
|
[] |
[
"http://www.princeton.edu/grandchallenges/energy/research-highlights/ocean-acidification/"
] |
[
[
"http://scrippso2.ucsd.edu/plots",
"http://rsta.royalsocietypublishing.org/content/369/1943/1980",
"http://www.annualreviews.org/doi/full/10.1146/annurev.marine.010908.163855?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed"
]
] |
|
2litj3
|
why are 3d printed gun such a big deal?
|
3D printed guns have been all over the news in the last year or so, but I don't really get it. I understand that now anyone can print their own gun at home, but just molding a gun and its parts can't be a lot harder, right? Why is the 3D printed gun different, is it just that it's a LITTLE easier? Or am I missing something?
EDIT: thanks for all the answers, I think I understand it little better now!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2litj3/eli5_why_are_3d_printed_gun_such_a_big_deal/
|
{
"a_id": [
"clv678n",
"clv6gcy",
"clv6ith",
"clvc222",
"clvcrin"
],
"score": [
13,
6,
3,
3,
2
],
"text": [
"Molding a gun and its parts takes a professional with lots of experience and knowledge, along with the expensive molds/etc. \n\nA 3D printer you can buy at staples.",
"because gun grabbers didn't know that you're totally allowed to build your own gun without a license and without serial numbers. but now that 3d printing has made it into mainstream, it's a huge deal.",
"Many of the things a 3D printer can do can be duplicated by someone skilled at casting and molding plastics (or other materials), but a 3D printer means *anyone* can do it.\n\nIf there were as many 3D printers in the wild as there are, say, laser printers, this would mean that anyone could potentially have an almost traceless non-metallic firearm. Easy access to firearms (notwithstanding what adherents of /r/thegunmetalgraypill or whatever might say :-) directly causes gun misadventure and violence at a much higher rate than it causes good-guy-with-a-gun-stopping-bad-guy-with-a-gun activities. That makes a lot of people concerned about printed firearms.\n\nRight now printing firearms isn't a mature process -- really, using 3D printers at all is still fairly techie and niche. But that won't always be the case.",
"Just to add, the responses so far seem to have covered most of the concerns people have with 3D gun printing.\n\nTo an American, who can manufacture his own, unlicensed gun without a serial number (TIL) then 3D printing of guns might not seem like a big deal. Here in the U.K though the concern is more valid as it could give people an easy way to get hold of a handgun which (rightly or wrongly) we as a nation have decided is a serious crime and very dangerous.",
"Also, because 3D printers use plastic to mold items, there has been concerns about guns that could be slipped through metal detectors. For now though, printer plastic remains too brittle for use like that. It would shatter when you pulled the trigger. "
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[]
] |
|
4f3zle
|
how can we determine gender from handwriting? what makes some handwriting "girly"?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4f3zle/eli5_how_can_we_determine_gender_from_handwriting/
|
{
"a_id": [
"d25p0yr",
"d25p1sl"
],
"score": [
4,
2
],
"text": [
"Women develop fine motor skills earlier than men. When leaning to write they have already developed past a males, and at that point I'm guessing they develop habits (better or worse) and they take over later in life. ",
"Women develop their fine motor skills about 2-3 years sooner than boys. That just happens to coincide with the time we teach handwriting in schools. So it seems like girls have better handwriting than boys. \n\nThat is not to say that some boys cannot have better handwriting than some girls, but on average, girls have the better handwriting.\n\nThey also practice more (girls are more likely to keep a journal and do art projects when they are bored). But that's just a product of society and not biological."
]
}
|
[] |
[] |
[
[],
[]
] |
||
5iq42u
|
why is it that western and mid-western states (nevada, colorado) have very clean borders (demarcations with almost straight lines) whereas eastern states (florida, n.carolina) have not so clean borders?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5iq42u/eli5_why_is_it_that_western_and_midwestern_states/
|
{
"a_id": [
"dba3nb0"
],
"score": [
5
],
"text": [
"Eastern states were often settled first, and divided up later. Even where not, they tended to be divided along natural boundaries 0 the state goes to this river, for example. So the boundaries are as random as the natural border.\n\nIn the west, the states were divided almost before people lived out there, certainly before they were extensively mapped and such, so they just said \"the state goes to this latitude and this longitude.\" Thus, straight lines."
]
}
|
[] |
[] |
[
[]
] |
||
4xc0lk
|
Why a spacecraft reentry has to be so violent? Why don't they make reentries at slower speeds to avoid all the heating up and stuff?
|
askscience
|
https://www.reddit.com/r/askscience/comments/4xc0lk/why_a_spacecraft_reentry_has_to_be_so_violent_why/
|
{
"a_id": [
"d6eadv9",
"d6ebws1",
"d6ec1rf",
"d6egvjb",
"d6eop98"
],
"score": [
29,
7,
32,
2,
2
],
"text": [
"You need at minimum about 7 times the mass of you payload in fuel to slow down from orbital velocity. That's discounting the mass of the tanks and engines you would need to use this fuel. To significantly slow down a spacecraft using a propulsive system would require a huge increase in mass that would make it unlaunchable. A heat shield is relatively light and \"simple\" way to slow down.",
"You can't do a slow re-entry, because slowing down would require burning fuel which you no longer have after spending it all to get up there. And if you attempt re-entry at a shallower angle so there's less friction you don't slow down enough, so you come back out of the stratosphere layer and then ping off into deep space (though you do not, as often quoted, bounce off the outer layer).\n\nXKCD touched on the subject [here](_URL_0_).",
"Here's an important rule about space travel - it is exactly as hard to slow down in space as it is to speed up. You need a huge, two or three stage rocket to get into orbit, so you'd need the same huge rocket to slow down again. But you'd need to get that rocket into orbit - and that huge rocket got just a small capsule into orbit, so can you imagine the size of a rocket needed to launch a whole huge rocket?\n\nSo we use the earth's atmosphere to slow us down instead. All we need is a heat shield.",
"Thanks for your answers, guys. Now it make sense to me",
"Could you in theory follow the curvature of the earth and use a slow micro bursts until you albeit slowly enter earths atmosphere on the landing gear side of the shuttle and then glide or fly like an airplane to your destination?"
]
}
|
[] |
[] |
[
[],
[
"https://what-if.xkcd.com/58/"
],
[],
[],
[]
] |
||
d3tw4w
|
In mid-1863, Vicksburg fell, and the Confederacy was officially split by the Union controlled Mississippi. How did this change the levels of support, and perception of the effort, within the regions of the Trans-Mississippi still under Confederate control?
|
To be sure, I figure that Vicksburg falling was more symbolic than *literal* as it wouldn't be impossible to slip through, but I would expect that that symbolic loss, with the Union now able to patrol the entire river unmolested by shore batteries or enemy ships, would be a pretty devastating blow not just to morale generally, but most specifically to those now cut off from 'the heart' of the Confederacy.
So how did the public in places like Arkansas or Texas respond to this, and what kind of impact did it have on support for the war: both within the civilian population as well as the military stationed there?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/d3tw4w/in_mid1863_vicksburg_fell_and_the_confederacy_was/
|
{
"a_id": [
"f05aghi"
],
"score": [
21
],
"text": [
"The Trans-Mississippi Confederacy was essentially an orphaned entity after the U.S. closed the Vicksburg/Port Hudson corridor in July 1863. People were pretty easily resigned to it, to be honest. The primary sources I've read all felt like they knew that it was coming, and they knew that it meant they would get no more support from the Confederate government. By this point, they had grown used to feeling abandoned and neglected. In early 1862, a U.S. Army invaded Arkansas from Missouri and trounced the biggest Confederate Army ever assembled west of the Mississippi River. That Confederate Army then completely bailed on Arkansas and crossed the Mississippi to fight U.S. Grant's army instead. The U.S. Army left alone in Arkansas marched pretty much unopposed through the state - as far as their supply lines would allow. They ended up freeing thousands of slaves in the Arkansas Delta and setting up a Union enclave on the Mississippi River port of Helena.\n\nThe Confederacy sent Maj. Gen. Thomas C. Hindman, a former U.S. Congressman from Arkansas, back to his state to get things under control. He promptly pissed off EVERYONE by declaring martial law, enforcing conscription, and encouraging people to form guerrilla bands to attack Union soldiers. These bands, of course, ended up killing and robbing indiscriminately. So people weren't feeling very positively toward the Confederacy by mid 1863 anyway.\n\nHindman actually managed to build an army, which promptly got thrashed at the Battle of Prairie Grove and pretty much melted away on the retreat. A few weeks later, the U.S. captured the largest body of Confederate troops remaining in the state, 5,000 men, at the Battle of Arkansas Post. This was January 1863 and Confederate Arkansas was already kaput.\n\nLittle Rock fell in September 1863. The Confederate state government retreated to Washington, in southwest Arkansas - not far from the Louisiana state government in exile at Shreveport and the Missouri Confederate state government which was at, I think, Marshall, TX or somewhere else in the area. The Confederate Trans-Mississippi Department was also headquartered at Shreveport, commanded by Lt. Gen. Edmund Kirby Smith. By late 1863, organized Confederate authority in the Trans-Mississippi had greatly diminished its geographic scale of control. What was left was so isolated that it was referred to as \"Kirby Smith's Confederacy.\"\n\nWhen Smith was appointed to command the Trans-Mississippi in February 1863, he was bummed because he knew it was a dead-end job. \"You might as well bury me,\" he wrote to Jefferson Davis.\n\nTo sum it all up, the fall of Vicksburg fulfilled the long-running fears of people in the Trans-Mississippi, that they were on their own.\n\nSources:\n\nJeffrey Prushankin, *A Crisis in Confederate Command*\n\nWilliam L. Shea, *Fields of Blood: The Prairie Grove Campaign*\n\nThose will get you started. To be honest, a lot of this is from memory since I'm sort of writing a PhD dissertation on Civil War Arkansas."
]
}
|
[] |
[] |
[
[]
] |
|
a1jmhz
|
What are the advantages/disadvantages for an organism to having a small or a large number of chromosome pairs?
|
askscience
|
https://www.reddit.com/r/askscience/comments/a1jmhz/what_are_the_advantagesdisadvantages_for_an/
|
{
"a_id": [
"eaqqxtd"
],
"score": [
3
],
"text": [
"There are clear advantages to having more chromosome pairs:\n\n1. Gene redundancy: multiple copies of the same gene reside within the genome, so mutations in a single gene don’t necessarily lead to the complete disruption of protein synthesis since the duplicate gene will still function normally.\n\n2. Heterosis: sometimes a hybrid organism (i.e. offspring of parents from two different species) has a higher chance of survival than its parents due to an excess number of chromosome pairs.\n\n3. Asexual reproduction: pretty self-explanatory. Self-fertilisation and reproduction have their benefits, evolutionarily speaking.\n\nThe main disadvantages of having a large number of chromosome pairs are that there is more nucleic material, so more energy is needed for DNA replication, and there is a higher risk of genetic mutations."
]
}
|
[] |
[] |
[
[]
] |
||
7k0q1b
|
how are cabinet members chosen?
|
Is it up to the discretion of the president to do this or is there a longer process? If it is up to just the president, how is this allowable in terms of a constitutional government?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7k0q1b/elif_how_are_cabinet_members_chosen/
|
{
"a_id": [
"dralx04"
],
"score": [
3
],
"text": [
"Per the law, the POTUS nominates the member and then that member is confirmed by the Senate. That is all that is actually legally required.\n\nIn practice, the POTUS will have a much longer vetting process run by various staffers or will dole out these nominations as repayment for political favors.\n\nIt is allowable because that is how the Constitution lays out the process in the Appointments Clause (Article II, Section 2, Clause 2):\n\n > He [the President] ... shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States, whose Appointments are not herein otherwise provided for, and which shall be established by Law: but the Congress may by Law vest the Appointment of such inferior Officers as they think proper, in the President alone, in the Courts of Law, or in the Heads of Departments."
]
}
|
[] |
[] |
[
[]
] |
|
2bb8yb
|
Are astronauts on the ISS able to recognize constellations? How far away from the Earth's surface could you go before they become "skewed"?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2bb8yb/are_astronauts_on_the_iss_able_to_recognize/
|
{
"a_id": [
"cj3mhhf",
"cj3mzuw"
],
"score": [
56,
12
],
"text": [
"Orbiting the Earth makes no difference in what you see in the night sky. If you think about it, you'll realize that as the Earth orbits the Sun each year, it covers a much, much greater distance, and yet the constellations don't appear to change their form or their relative positions. In fact, anywhere in the Solar System, the constellations would [look the same](_URL_2_).\n\nIf you went to Alpha Centauri -- the next nearest star to the Sun -- the constellations would barely be changed, with one really cool exception: the Sun would [now appear](_URL_1_) in Cassiopeia!\n\nAs you get a few dozen light-years away, you would notice more appreciable changes. There is a brief discussion of this all [here](_URL_0_). The basic rule of thumb is that the farther away the stars are, the more you'd have to travel to see their relative positions change. Of course, in any given constellation we see from the Earth, the stars can be at quite a range of distances.\n\nEdit: Filled in a missing a word.",
"In 6 months the Earth travels 186 million miles to the opposite side of the Sun and the constellations still look the same. The ISS is only 200 miles above the ground."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Extraterrestrial_skies#Extrasolar_planets",
"http://earthsky.org/space/night-sky-appearance",
"http://curious.astro.cornell.edu/question.php?number=713"
],
[]
] |
||
1pp9uo
|
If a person were spinning perfectly horizontally in space, could they slow themselves by putting their arms out? Much like an ice-skater?
|
If we take the question further, what if the person had a pack with heavy chains that they could fling outward. Would this slow their spin down at all? Co-worker just watched Gravity...
|
askscience
|
http://www.reddit.com/r/askscience/comments/1pp9uo/if_a_person_were_spinning_perfectly_horizontally/
|
{
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"cd4n3bp",
"cd4pjmb",
"cd4q7cp"
],
"score": [
11,
8,
2,
2
],
"text": [
"I haven't seen Gravity, but the essential idea you are referring to is conservation of angular momentum. The answer to your question is yes, you could slow down your rotational speed by moving mass away from the rotational axis. \n\nBeing in space (away from the effects of gravity) should have no effect on this principle.",
"Yes. It directly follows from the law of consevation of angular momentum. Equation is\n\n **L** = **r** × **p** \n\n**r** is Perpendicular distance to rotational axis, so if you increase **r** momentum **p** have to be decreased accordingly and therefore you will spin slower.\n\nConservation of angular is very important physical law, in space especially, since thanks to gravity trajectory of almost everything in space is a conic section. Put this together with the equation above and you should see the reason why planets orbit faster when they are closer to the Sun.",
"Your total angular momentum would remain the same forever, due to the lack of air resistance. Putting your arms out would slow you down due to conservation of angular momentum as mentioned in other answers.\n\nThrowing heavy items away would work to stop your spin, this is because you'd be transferring some of your angular momentum to the item you tossed.",
"... I don't get this.. but I don't have a science background. If nothing existed in the universe other that a giant vacuum and me... and I am spinning... how do I even know I am spinning? Isn't just relative to other objects?"
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
1z5mw3
|
why is berkshire hathaway (brk-a) being traded at $171,000/share?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1z5mw3/eli5_why_is_berkshire_hathaway_brka_being_traded/
|
{
"a_id": [
"cfqqhjs",
"cfqqsn6"
],
"score": [
5,
3
],
"text": [
"Because there aren't many shares for sale. That means that each is worth a bigger % of the value of the company.",
"They chose to never split the shares. "
]
}
|
[] |
[] |
[
[],
[]
] |
||
8vtmj8
|
Has sexual activity changed with changes in personal hygiene - in particular was oral sex common when people bathed very rarely?
|
Edit: With the hygiene query this was prompted in part by remembering how Napoleon wrote to Joséphine telling her:
“Je reviens en trois jours; ne te laves pas!” (I will return in three days. Don’t wash!)
which is presumably referring to cunnilingus - so was guessing that, ahem, tastes had changed, and wondered what trends there have been in this area.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/8vtmj8/has_sexual_activity_changed_with_changes_in/
|
{
"a_id": [
"e1qizev",
"e1rrwyp"
],
"score": [
72,
3
],
"text": [
"There's an eighth to ninth century Old Irish penitential (a text that lets you know the penance for different sins) with explicit reference to oral sex:\n\n*Nech dogni etrath o belaib iiii anni in cet-fecht ma gnathach acnapthe vii annis.*\n\n*Nech touisim a sil hi gin a banscal penneth dib línaib v annos ma gnathach vii annos.*\n\nIn English these are:\n\nAnyone who performs the fornication of the lips penance for four years if it is their first time but if it is usually their custom seven.\n\nAnyone who spills his seed in the mouth of a woman must pay full penance for five years, if it is a usual thing, seven.*\n\nThere are few references to oral sex, particularly on women, but reading between the lines the greater concern usually if not always seems to be that the greater sin is ejaculation not inside a vagina for the purposes of procreation. This is St Thomas Aquinas' view and is the one that has had the most impact on surviving literature. Unfortunately without a more significant set of data, it's possible to know what sort of sex people were expected to be having, but less so what sort of sex they were having and how much they enjoyed it. However, if there's a rule about it, the assumption is that enough of it has happened that the Church has felt the need to take a stance on it.\n\nYou can read the penitential on JSTOR: _URL_0_\n\n\n*also interesting on a tangent is the linguistic construction here. In modern oral sex the way we talk about it is usually that your active participant is doing and your passive partner is receiving. There are exceptions but I'm not sure this is the place for a friendly chat about face fucking. Anyway, if you look at this and assume primarily hetero partners (although pre-Christian Ireland has a lot more same sex shenanigans than you might have expected), the male is the active partner whether he performs oral sex on her or ejaculates in her mouth. The assumption is that the male is always the active partner and the female always the passive receiver. Which has nothing to do with hygiene but interests me. \n",
"Not answers about sexual activity per se, but a few past answers here on hygiene which may interest you:\n\n/u/mikedash [on the smells of a city \\(and its people\\)](_URL_0_)\n\n/u/notepaperpen [on medieval hygiene](_URL_1_) (posting the thread in full here, since there are a few queries about the main answer that request a bit more specificity)\n\n/u/voxscholasticus [on whether people in the middle ages smelled bad](_URL_2_)"
]
}
|
[] |
[] |
[
[
"https://www.jstor.org/stable/30007320?seq=1#page_scan_tab_contents"
],
[
"https://www.reddit.com/r/AskHistorians/comments/5dwk60/how_bad_would_it_have_smelled_in_a_medieval_city/da84g7z/",
"https://www.reddit.com/r/AskHistorians/comments/7xpbxp/what_was_hygiene_like_in_medieval_times/",
"https://www.reddit.com/r/AskHistorians/comments/1gh0x8/did_everybody_smell_bad_in_the_in_the_medieval/cak60wt/"
]
] |
|
7fv07s
|
how does one alphabetize kanji?
|
English for example has 26 letters in defined order and words or names can be sorted easily this way, for example, making directory for business employee or phone book, or dictionary for words. But in Asian countries like Japan, their name aren't spelled in letters but in kanji and there can be several thousand different symbols for words or names.
How would a school sort student's name? Or how would a typical Japanese dictionary be sorted so they can quickly look up word?
Not just Japan, but many Asian countries (China, Korea, etc)
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7fv07s/eli5_how_does_one_alphabetize_kanji/
|
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"Korea has an alphabet song, just like English. \n\nTheir is an order is 가 나 다, etc. \n\nSo, names are ordered by their \"alphabet\" first symbol.",
"There are three different kinds of character systems in use in East Asian languages, ones that represent simple sounds (alphabets), ones that represent whole syllables (syllabaries), and ones that represent concepts (logographic systems). They're treated differently, and the same language sometimes uses multiple sorts (for instance, written Japanese uses both the logographic kanji and the syllabaries hiragana and katakana).\n\nAlphabets and syllabaries typically just have a canonical ordering of the characters, and they're sorted lexicographically in the usual way.\n\nLogographic writing systems are really what you're asking about, though, and those have a couple different ways. The most common is the radical-and-stroke system. Each character is classified into groups based on what the \"primary\" component (known as a radical) is, and those radicals are then ordered. Within a single radical, characters are sorted by the number of lines (known as strokes) used in the character, from least to most. Within a group of characters with the same primary radical and number of strokes, ties are broken relatively arbitrarily (usually there's a convention for this).\n\nAnother way is to sort them based on how they would be written in a different writing system that has a built-in sorting method. Some Japanese dictionaries and such are done this way, by sorting words based on how they'd be written in kana. Some languages that use CJK characters don't have such an option, though, since they don't have more than one writing system.",
"With Chinese it's done by radical and stroke order (I believe that Kanji are organized similarly).\n\nMaking it very basic: \nThere are sort of two types of characters, ones that are relatively simple in construction and do no require a lot of lines to write and more complex ones that have a bunch of different components.\n\nFor the more simple characters, like hand (手), it's simply a matter of how many stokes (individual lines) you use to write the character. In this case 4 strokes. This character served two purposes. By itself it means hand, but it *also* is what's called a radical and it, or a modified version of it, is included in words that are semantically associated with \"hands\" or grasping, etc. It can, very loosely, be thought of as being like a root word in English.\n\nI open my dictionary (it's actually in front of me as I write this), look for the initial section that has those simple characters, look under the portion that has 4 strokes, and look for the character. This then tells me the next place to go in the dictionary, which in this case is to a portion of the dictionary that contains words that include 手 as part of the writing.\n\nWhen I go to the portion of the dictionary that lists words that include 手, I am again presented with a list of characters listed in order of how many strokes they involve. In some dictionaries this is a separate list with page numbers for subsequent characters, in other dictionaries this takes you right to that portion of the dictionary (similar to going to the B portion of an English dictionary)\n\nIn any event, in the 手 portion of the dictionary, one of the first words you encounter is this character, 承 (to hold or to bear) which includes the 手 character, radical in this case (look at the center of the character), plus 4 additional strokes. Other more complex characters that incorporate the 手 radical have more strokes and are listed further down.\n\nThis sounds complicated, but it makes a good bit of sense, once you're used to it.\n\nAn English analogy would be the following:\n\nLet's say you are looking up words that include -scope in them. Scope by itself has a meaning (watch or see) and is 5 \"strokes\" (we will use letters as strokes in this case). You go to the initial portion of your dictionary and look for words that include 5 letters/strokes... andro, cadre, indri, *scope*.\n\nYou then go to the page indicated to see what other words include \"scope\". This starts with the word scope, then the words get longer depending on how many additional letters/strokes they include in addition to the initial 5 used to write \"scope\".... epi*scope* (3 additional strokes/letters), cryo*scope* (4 additional strokes/letters), fluoro*scope* (6 additional strokes/letters), etc.",
"Korean doesn't fall into this category: it actually uses a real alphabet. Those characters that look like complicated Chinese-style logograms are actually syllable blocks, made up of (usually) two or three letters that represent sounds, and these letters have a fixed order (however, North Korea and South Korea use different alphabetical orders).\n\nFor example, the writing system is called \"한글\". It's two syllables, and each syllable is read from left to right and from top to bottom. The individual letters are:\n\n* ㅎ = h\n* ㅏ = a\n* ㄴ = n\n* ㄱ = g\n* ㅡ = eu (sometimes transliterated \"ŭ\")\n* ㄹ = l\n\n-- so: \"hangeul\". No problem at all: \"ㅎ\" is 19th in the South Korean alphabet.\n\nChinese ideograms, or kanji in Japanese, are more complicated. They're sorted by radical and stroke count.\n\nThe \"radical\" is the part of the character that gives you a clue about the meaning of a word. For example, the character \"媽\" means \"mother\": the radical is on the left, \"女\" and means \"woman\". The rest of the character, \"馬\", gives a clue about the pronunciation. Its actual meaning is \"horse\", but in Mandarin Chinese it's pronounced \"mǎ\". This is *almost* the same as \"mā\", the word for \"mother\", so the whole character means: \"This is a word for a woman, and it sounds a bit like the word for a horse.\"\n\nThere are a bit more than 200 radicals in Chinese, and they're sorted according to the number of strokes you need to write them. [Here's a list of the 214 radicals encoded in Unicode](_URL_1_) -- notice how they get more complex the further down the list you go.\n\nSo most dictionaries are arranged such that you first look up the radical, and then you look for the character you're searching for, again according to the number of strokes. If you want to look up \"媽\", for example, you need to first find \"女\", which is the 38th radical. You'll have a long list of characters that use that radical, again sorted from least strokes to most strokes -- you know that \"媽\", which needs 10 extra strokes, is going to be further down the list than \"奴\", which needs 2.\n\n[This is the list of characters that use the 38th radical](_URL_0_) -- there are 681 in all.",
"In Japan at least, they're not organized by Kanji.\n\nJapanese has three writing systems; Hiragana and Katakana (which are phonetic systems), and Kanji (which are Chinese symbols). For their version of alphabetization, the names will be spelled out in Hiragana/Katakana, and then organized following the same organizational system of those writing styles.\n\nAlternatively, they'll sometimes use Romanji (which is just our Latin alphabet, specifically the English variation) and alphabetize according to that system."
]
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[],
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"https://en.wikipedia.org/wiki/Kangxi_radical#Unicode"
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|
15p4o3
|
Is there anything like Sci-Fi literature dated before 1900/1800 ?
|
Thank you all for your answers, my curiosity has been satisfied.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/15p4o3/is_there_anything_like_scifi_literature_dated/
|
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"\"[True Story](_URL_0_)\" by Lucian dates to the 2nd century AD and includes travel to outer space, alien civilizations, and interplanetary war. However, the motivations weren't quite to write \"science fiction,\" as it wasn't really based on any science, and rather to satirize those who wrote fantastic tales and claimed them to be true. It might better be classified as fantasy, though many of its themes are those used now by science fiction.",
"Voltaires work called Micromégas is the oldest piece I can think of, and quite revolutionary.",
"*Frankenstein* by Mary Shelley is the earliest example I can think of. It's not very heavy on theoretical science though, so it could be considered a gothic romance with sci-fi elements. Science fiction is closely associated with and derived from romance and gothic literature. also have a look at a genre called [Scientific Romance](_URL_0_), which, as people have pointed at, was championed by authors like Jules Verne and H. G. Wells.\n\nBy the way, /r/AskLiteraryStudies is a great place for this kind of question, though sadly it's much less active than this subreddit.\n\nEDIT: grammar and added nuance",
"Johannes Kepler in addition to his work in astronomy and giving us his three laws of planetary motion wrote what is arguably the first work of science fiction, *[Somnium](_URL_0_)* between 1620 and 1630.",
"It's interesting that you pick the dates 1900 & 1800, as if they're similar in the history of science fiction. Actually, the modern genre of science fiction started *between* these two dates, so you'll get totally different answers to these two questions:\n\n* Is there anything like Sci-Fi literature dated before 1900?\n\n* Is there anything like Sci-Fi literature dated before 1800 ?\n\nFor the first question (before 1900), I would point you to the works of H.G. Wells, Jules Verne, Mark Twain's 'A Connecticut Yankee in King Arthur's Court', and, of course, the first science fiction work, 'Frankenstein' by Mary Shelley. These are the early works of science fiction.\n\nFor the second question (before 1800), I would draw a blank. There certainly was literature before 1800 which had elements of what we now call \"science fiction\", but they were not written to be science fiction - if we take science fiction to be, [as Isaac Asimov defined it](_URL_0_):\n\n > ... that branch of literature which deals with the reaction of human beings to changes in science and technology.\n\nThose earlier works which contain science-fictional elements - such as Lucien's 'True Story', or Swift's 'Gulliver's Travels' - were mainly writing social satires. Lucien didn't investigate how living on the Moon affected the beings there; Swift didn't write about the technology that caused Laputa to fly - these were merely devices to confirm to their readers that the society being described was not, definitely not, related to the society of the reader.\n\nSo, even though they had science-fictional elements, they weren't science fiction.\n",
"You may be interested in [these previous questions regarding this topic](_URL_0_) on our Popular Questions page (which is linked at the top of every page in this subreddit, and in the sidebar).",
"If you go with Darko Suvin's definition of science fiction, \"a literary genre whose necessary and sufficient conditions are the presence and interaction of estrangement and cognition, and whose main formal device is an imaginative framework alternative to the author's empirical environment.\"\n\nThen Thomas More's Utopia is a terrific early (1516) example. I've actually got a paper pending publication on its place in the canon.",
"\"Memoirs of the Year 2500\" (1771) by [Louis-Sébastien Mercier](_URL_0_) is one of the earliest examples of time travel in fiction. Like most time travel literature, it's mostly interesting (imho) because it says a lot about the period in which it was written. Specifically, it provides an interesting moderate-liberal view of an ideal society in France right before the revolution. I should probably add that although time travel is now a common science fiction theme, it's presented as a \"real\" dream in the book - so it only meets the criteria for being *like* sci-fi.\n\nAlso, some of Edgar Alan Poe's short stories make fantastic predictions about the potential of balloon technology. The short stories \"The Unparalleled Adventures of One Hans Pfaall\" and \"Mellonta Tauta\" come to mind. The first describes a balloon journey to the moon, and the second takes place on a massive dirigible in the distant future.",
"Cyrano de Begerac wrote a couple in the mid 17thC which include a trip to the moon in a carriage powered by fireworks."
]
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"http://en.wikipedia.org/wiki/Definitions_of_science_fiction#In_chronological_order"
],
[
"http://www.reddit.com/r/AskHistorians/wiki/dailylife#toc_3"
],
[],
[
"http://en.wikipedia.org/wiki/Louis-S%C3%A9bastien_Mercier"
],
[]
] |
|
nsklm
|
the game of craps
|
I've always wanted to play (especially since I've been told that it has the best odds versus the house) but I just don't get it. The one time I played I was so nervous that I was going to mis-throw the dice that I didn't pay attention to how I lost.
Are 7's good or bad? How should I bet? How can I make my money last? And all those good questions.
Thanks for your help!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/nsklm/eli5_the_game_of_craps/
|
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"For some reason this question keeps coming up. [This seems to be the best answer.](_URL_0_)",
"1. Place bet \n2. Roll dice\n3. If you get a 7 or 11, you win\n4. If you get a 2, 3, or 12, you lose\n5. Otherwise, what you roll is your *point*\n6. Roll again\n7. If you get a 7, you lose\n8. If you get your point, you win\n9. Otherwise, go back to step 6\n\nThat is it in a nutshell. The rest of the table is either betting with or against the shooter, or are making various propositional bets about how the round will go.",
"For some reason this question keeps coming up. [This seems to be the best answer.](_URL_0_)",
"1. Place bet \n2. Roll dice\n3. If you get a 7 or 11, you win\n4. If you get a 2, 3, or 12, you lose\n5. Otherwise, what you roll is your *point*\n6. Roll again\n7. If you get a 7, you lose\n8. If you get your point, you win\n9. Otherwise, go back to step 6\n\nThat is it in a nutshell. The rest of the table is either betting with or against the shooter, or are making various propositional bets about how the round will go."
]
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[] |
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[]
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|
v7fbg
|
Has the total number of organisms on earth at a given time increased, decreased, or remained generally static over the last 500 or so years (more recent history)
|
askscience
|
http://www.reddit.com/r/askscience/comments/v7fbg/has_the_total_number_of_organisms_on_earth_at_a/
|
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"Are you including prokaryotes (i.e. bacteria and archaea)? If so, the number is so large as to be more or less incomprehensible.\n\nThere are something like 10^15 bacterial cells (each one being considered an individual organism) in your body alone (also interesting to note: that's ten times as many of \"your\" cells as there are in your body), meaning that the population of bacteria that live directly on or in human bodies on planet Earth is about 7*10^24 .\n\nThat's only those associated with humans.\n\nAnyways, I don't really have an answer to this question. Just wanted to point out how damn many microbes there are on this planet.",
"This might be better stated as organic mass on the earth.",
"This is going to be mostly speculation, but only because it's probably the best you're going get with a question like this (Biological research just typically isn't framed that way, although if anyone is able to find any hard evidence relating to this question I'd be equally as curious as to the findings).\n\nOdds are it's remained more or less static over the past 500 years or so. That's an *awfully* short amount of time in terms of evolutionary and ecological development. There hasn't been a major mass extinction event since the Cretaceous (65 mya) and the most recent significant extinction event was during the Ice Age transition (about 50 kya). Probably the only relevant environmental development with respect to planet-wide ecology within this time frame is the industrialization and further proliferation of humans, but I highly doubt we've affected the overall biomass distribution to a significant degree (we've certainly destroyed our fair share, but have probably contributed a more or less equal amount as well either directly or indirectly).\n\nNature tends to be a pretty balanced ebb and flow of stability (almost remarkably so) and change is usually painstakingly slow and gradual from a human perspective. 500 years just probably isn't enough time to having any significant change in the overall biological state of the planet barring radical and immediately widespread environmental changes.",
"Short answer is, no one knows. There is so much stuff going on on the planet at all times that humans are not and could not be aware of. A big factor here is the oceans. There are many species that everyone is familiar with (like the Great White Shark) whose lifecycles shrouded in mystery because so much takes place in the deep blue sea, far from land. Just imagine what goes on with the species we've never even seen, and you will have a good idea why answering your question is nearly impossible. [Here is a timeline of species that have gone extinct since humans lived] (_URL_0_). This does not answer your question, of course, but this will give you at least some indication of what we do know about the subject.",
"In general we would expect the biomass of the earth to remain roughly constant (assuming that the ratio of producers to consumer levels stays the same) because the energy coming to earth from the sun is constant. then you could find if the number of organisms has been increasing or decreasing based off the change in average mass of organisms. although, i would expect it remains fairly constant because so much of life is made up of the very small like bacteria and insects."
]
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||
1wbdex
|
why water flows ?
|
the question really is about why does a liquid substance flow like it does... taking the shape of what comes on it's way... always going down if it can..
I know it sounds like a stupid question, but there is no stupid question when you are five.. and actually, it's my friend's daughter who is just five who came with the question.... and we are still not sure how to answer her ... help?
edit: grammar (and sorry if there is more mistakes, english is not my first language)
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1wbdex/eli5why_water_flows/
|
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"Basically the force holding a liquid's molecules together is weaker than other forces that its experiencing. The most significant one usually being gravity. Gravity pulling down on the molecules in the liquid overcomes any sort of connection between the molecules, and the liquid will flow across whatever surface it's on until something stops it (like the sides of a container, or the floor).\n\nIn a solid object, there are forces between the molecules that hold it together against those other forces. If you apply a big enough force to a solid, however, you can deform them, often in ways that look very similar to a liquid. An example would be glaciers. When a glacier is growing, new ice gets added to the top, and the weight of all that ice cause the glacier to \"flow\" down the mountain, in a manner in many ways similar to how liquid water would flow, although at a much slower rate."
]
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|
[] |
[] |
[
[]
] |
|
390e26
|
why are some things prioritized in media and other things aren't?
|
For example the school shootings in Pakistan vs Almost the same event in an African country I can't remember the name of (due to almost no news reports). The only reason I heard about the killings in this country was because of people complaining about there being no news reports on it even though the death-count was relatively high.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/390e26/eli5_why_are_some_things_prioritized_in_media_and/
|
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"When it comes to international news in North America, there are two sources primarily used by news companies. The Associated Press in the USA and The Canadian Press in Canada. Once a story is found at a media organization it has to pass what I like the call the \"do I care,\" test. \n\nIf you don't care about a story as a news journalist, or if you don't think that the audience will care about the story, you don't cover it. A story that no one will be interested in is pointless. Media organizations struggle year-round to get your eyes and/or ears focused on them. The average listener getting bored threatens ratings/circulation/clicks, which directly hurts your bottom line. \n\nMost media organizations are here for entertainment because that's what sells. I don't mean Entertainment stories, though those are often successful, but rather something to amuse the viewer. If it won't draw your eyes, chances are those \"boring\" stories will be ignored. ",
"Well, what gets ratings? We don't care about black kids dying, but we care about evil islam being evil. \nThen, there are also things like not pissing off government, because they might make the reporting job harder...\n\nIf you are interested, look up the propaganda model - basically a theory on how even without direct intervention, we end up with filtered media. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
2c89vq
|
Why can light rays never approach one another in the event horizon of a black hole?
|
I know that in the event horizon of a black hole light rays can only run parallel to each other or away from each other, because if they would meet they would fall into the black hole and therefor never have been in the boundary of the black hole...but I don't know why these light rays cannot just continue and stay in the even horizon?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2c89vq/why_can_light_rays_never_approach_one_another_in/
|
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"The definition of \"parallel\" changes because space-time itself changes in the presence of mass. Leave aside the mysteries of black holes for a moment. Suppose I send two space ships out to some distance away from the sun. Say they're 100 000 miles apart, and they use a system of lasers to align themselves and then shoot out two *exactly parallel* beams of light toward the sun. When you measure them near the sun, you'll find that they're only (say) 95000 miles between each beam (The number is just something I pulled out, not a calculated value). \n\nSpace itself is bent by mass. In a way it's kind of \"compressed\" nearer to mass. Distances that were further apart far away are closer together near the mass.\n\nAs you can get closer and closer to a mass (because it's denser) you can pass through more of this curved space. So a neutron star, you might find (again made up numbers) that the beams are now only 50000 miles apart. \n\nAnd a black hole allows you to get \"perfectly close\" to the mass (in a classical interpretation, ignoring more complicated descriptions of black holes) so the beams (assuming they both pass through the event horizon of the black hole) will converge all the way onto the center of the black hole.\n\nInterestingly though, in these more extreme scenarios, because of the bending of *both* space and time, the path that the light takes may include things that look more like orbits or kind of spiraling into the object."
]
}
|
[] |
[] |
[
[]
] |
|
4hmioi
|
State of Britain after Rome but before the Anglo-Saxons
|
I've recently developed an interest in early British history and there's one question that's recently struck me.
Correct me if I'm wrong but the last roman legions were ordered to leave Britain in the early fifth century to defend the empire elsewhere and by the end of the century the first Anglo-Saxon kingdoms were forming in England.
My question is what was the political state of Britain in the time after Roman rule but between the Anglo-Saxon era? What factions/ people were in power? Was there organised resistance against the invaders? etc.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/4hmioi/state_of_britain_after_rome_but_before_the/
|
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"text": [
"OK this is a very broad question, as it arguably covers about 100-250 years of history across a very diverse area with virtually no primary sources that can be considered trustworthy. For example, 2 sources which early historians of the period placed a lot of trust in have had a lot of doubt cast on them: Zosimus stated that the \"Brettaniai\" threw out the Roman administrators after the evacuation of the final Roman Legions, but this is more likely to be referring to the Bretons (i.e from Brittany) rather than Britons. Also, the address of Emperor Honorius in 410 AD, which was seen for a long time as the final act of British secession from the empire, is actually more likely to be referring to a town in Italy (probably Bologna). Nevertheless, considering that you aren't asking for specifics and rather for the general political state of the island in the Sub-Roman period, this answer might be of help to you. \n\nRoman power in Britain could be considered to have been in decline as early as the rebellion of Carausius in 286, although Britain did still play an active part in the empire after this point (mainly through stripping it's shores and northern border of troops so warlords could try and usurp the imperial throne, with mixed success). This is probably the point at which the Roman administration stopped making the locals more Roman, and the British start making the administration more British. Although this turning point could be placed as late as the Great Conspiracy of 367: however by this point, the empire was not strong enough to exert real power in such a distant province. \n\nDistinct political units are difficult to place in this period. It is likely that in the North of the Country (Britannia Inferior) and in Wales that pre-existing tribes such as the Brigantes, who had never really been broken by the Romans, simply resumed tribal warfare and their previous structure, albeit with a lot of Roman influence in portraying their majesty. This is why when the Anglo-Saxon's established bases on the East Coast of what would become Northumbria, it took much more time to subjugate the indigenous peoples: they never really managed to in Cumbria. Celtic power was still too strong, unified under local kings, in the North and in Wales, aided somewhat by the fact that the mountainous terrain in these regions played to the strengths of Celtic Warfare such as at the Battle of Dun Nechtain, although this was Northumbrians against Picts rather than Brittonic Celts. The only real example of a battle between Germanic and Celtic armies in Northumbria is probably that chronicled in *Y Gododdin*, which was a crushing Celtic defeat. As *Y Gododdin* might imply, the Northumbrian Kings did eventually subjugate most of the North, but the transitional period was much longer than in the south.\n\nThe South was a different story. This was the first area to be Romanised in Britain, even before the Romans invaded. This had thoroughly broken most tribal power, and so there was nothing to fill the vacuum which resulted from the collapse of Roman Authority. Yet the area was not likely to have been an anarchist utopia of Villas and Towns. Warlords like Constantine III set themselves up in such Villas as Rockbourne in the New Forest and even contented for the rule of Gaul in short-lived empires. He is probably the best known warlords from this period, and most probably ruled areas of negligible size. The arrival of Germanic tribes in the region shattered this order. They settled in Coastal Areas (The Jutes in Kent and The Isle of Wight and Saxons initially in the Test Valley) peacefully, or at least with minimal confrontation. The Sub-Roman warlords could not contend with the power of the Saxon Kings, whose Rule was Sacred and unquestioned. They essentially filled the power vacuum of the South, from Devon to East Anglia, and assimilated the British into their society and culture. Those who could not simply fled rather than fight.\n\n Accounts in this area are also notorious for their inaccuracy. The Anglo-Saxon Chronicle passage for the arrival of Cerdic in 508 in Southampton Water, while probably accurate about the location of Arrival, is completely fabricated as to actual events. It details the glorious victory of Cerdic and the West Saxons against the mysterious (to say the least) King Natanleod at Tatchbury Mount which gave them control of the entire modern New Forest: the embryonic Wessex. However, this is bullshit. Natanleod is folk etymology for the village of Netley Marsh, near to Tatchbury Mount: Naet-Leah(meaning Wet Marsh or Wet Wood) became Netley, and so locals invented a fictional king to give their village a slightly more glorious heritage. Victorian historians, such as E. Guest, were also obsessed with the existence of semi-mythical figures such as Ambrosius Aurelianus, who they thought were the origins of the Arthurian Legend. No evidence has been found to suggest this, and much of the early academic writing on this subject is clouded by speculation on the subject. \n\nSo what actually happened? Well likely not much. It's much more romantic to imagine a valiant British resistance, particularly for myself as a proud Celt. There is a distinct lack of evidence for violent invasion in the south. We have evidence for the Carnage of the earlier Roman invasion (which I will give in the sources), but the archaeological record for this period is one of peace. While politically the region was in turmoil, with central government disintegrating as it's military guarantors fled to the continent, socially and economically, it has been argued that lack of taxation and conscription actually led to a period of prosperity. I'm not completely sold on the idea: the arrival of Germanic migrants must have upset the social balance somehow, and the fact remains that by the time Anglo-Saxon accounts start emerging the great Roman and Sub-Roman towns are abandoned ruins points to economic upheaval. But it's much better to think of this as change rather than decline. Villa economies were replaced by a system focused around the local warlord's hall. The system remained agrarian at heart. For the peasant, there would have been little difference over the period. \n\nBut what about the Anglo-Saxon invasion? Well it was more likely to be a migration. I say more likely, as Gildas, one of the few Romano-British writers of the time, states that: \n\n > Some of the wretched remnant [the native Britons] were consequently captured on the mountains and killed in heaps. Others, overcome by hunger, came and yielded themselves to the enemies, to be their [the Saxons] slaves for ever, if they were not instantly slain, which was equivalent to the highest service.\n\nThis would suggest a violent invasion. Yet the Archaeological record for the period has no real suggestion of violence. Yet it is certain that British refugees fled to places like Wales, Northern Spain and Brittany (the latter of which they practically took over). Gildas also had a very clear agenda in his writings, as he was a Priest and so hated the \"heathen\" Saxons. This might actually help to explain the exodus of the Christian Britons as Religious migration away from the Heathen settlers. The fact that the Anglo-Saxons almost immediately set up their rigid class system, with the Britons very much towards the bottom (although not the lowest of the low mind you), might also explain the flight of the British. \n\nSo in summary, political power in Sub-Roman Britain changed by region. Scotland obviously just carried on as it was, with the gradual arrival of the Gaels pushing the Picts to the North, as the decline of the Romans didn't affect them, aside from increasing raiding opportunities. In the North and in Wales, a combination of residual tribal authority with Roman influence on their style of rule and the synergy of Celtic Warfare and Local Geography allowed the Celts to severely delay Northumbrian hegemony of the region, although it was inevitable. This also meant that the culture of the North today is very different to that of the South, although the Vikings also played a part in that. In the South, there was little to no organised resistance, and most accounts claiming there was are very questionable: their agenda is likely to romanticise rather than document. While there was no sudden social and economic decline, and indeed there was a period of prosperity, lack of central authority and fragmentation of the region into Warlord fiefs allowed the Germanic migrants to either gradually assimilate or expel the indigenous British. \n\nTL;DR: The Northern Tribes probably fought the Anglo-Saxons for at least half a century, likely more. The Romanised South was politically hit harder by Roman withdrawal and so was overwhelmed by a largely peaceful Germanic migration.\n\nApologies for the terrible writing style, I'm quite tired atm. \n\n",
"Consider listening to the [The British History Podcast](_URL_0_) by Jamie Jeffers. He's not a historian, but rather a \"history communicator\". (He's had two AMA's in this subreddit). He's thorough (at the 130 episode mark he's only reached the mid-650s!) and does a good job of keeping the narrative moving along (not an easy task, especially when discussing the numerous kings/kingdoms and their progeny during the Anglo-Saxon period)."
]
}
|
[] |
[] |
[
[],
[
"https://www.thebritishhistorypodcast.com/"
]
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|
14v20k
|
How healthy is dog food?
|
I'm curious to know the research about what is best for a dog's diet, and if brain health for dogs is as important as it is for humans in terms of health and longevity.
Do dogs need essentially the same nutrients/nutrient balance that humans do to live healthiest? What is the optimal mix?
|
askscience
|
http://www.reddit.com/r/askscience/comments/14v20k/how_healthy_is_dog_food/
|
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"This is a difficult question to answer. There are plenty of dogs that make it well into old age with something like \"Old Roy,\" and other dogs that have died young despite having been fed a home-cooked diet comprised of all-natural foods. Fortunately, many dogs are capable of doing relatively well even on a diet that is higher in vegetable matter than their anatomy (teeth, digestive system, size of stool) would suggest.\n\nOf course, dog food is highly variable: it runs the gamut from foods that are high in grains and relatively low on quality protein and fat, to foods that are virtually all protein and fat with relatively little carbohydrate. However, for the purpose of processing, kibble has relatively high quantities of corn, wheat, and rice in order to make it easier to process, ship, and store.\n\nHaving actually read the National Research Council's book on [nutritional requirements for dogs,](_URL_0_) diet is extremely important for dogs. However, precisely *what* is best for them is up in the air. We know a lot about the mineral requirements, i.e.: how much iodine, calcium, magnesium, etc. is required, and AAFCO foods are generally well within those requirements.\n\nWhat we know less about is whether grains are beneficial; I would suggest that perhaps more research is required in this area, but it is unlikely to be forthcoming in that there is no financial benefit to excluding grains. The major companies will continue to produce grain-heavy mixes, and this may be why we see gastrointestinal problems in some breeds; we see that some of these disorders clear fairly quickly when fed a grain-free diet, although there's little in terms of research in that field.\n\nMacronutrient composition (the ratio of calories from carbohydrates, fats, and protein) is a much more difficult thing to gauge, and it even varies between breeds; it has been demonstrated, for example, that malamutes require a bit less fat and more protein than was previously thought for optimal performance while working under Arctic conditions. Strikingly, sources agree that there is no carbohydrate requirement in the dog; there was one erroneous study back in the 1980s that suggested carbohydrates were required for the dog to successfully fulfill its reproductive life cycle, and this was corrected with subsequent study that showed that the diets employed had too much fat; when the concentration of protein was increased, there were no reproductive problems.",
"Dog food companies conduct their own sort of research, which might be worth trying to look into. But remember that the goals of a dog food company may not only be what is most healthy. It is a pretty standard idea in pet food that good, healthy food = less, more solid waste, and I don't know if that has scientific backing, or is just something pet owners prefer. ",
"Another question: How healthy is dog food in terms of human consumption? Could a human survive on a diet of dog food?",
"It depends on the dog food, as there is actually very little legislation on it. There are different formulations out there, and not every dog food company performs adequate laboratory testing. In the US, AAFCO guidelines set up the minimum nutrient and energy profiles for dog foods, specific to the life stage (puppy vs. adult). They also monitor \"feeding trials,\" where animals are fed the specific food for 6mo-a year and are closely monitored health-wise. However, compliance with AAFCO testing is not mandatory.\n\nYou ideally want most of the protein to be meat-based: although dogs are omnivorous to an extent (\"facultative carnivores\") meat protein is generally thought to be more digestible and is more expensive, which is why it is sometime substituted for grain-based protein in cheaper diets. However, despite the hype about grain-free, most evidence supports than grain is not harmful for dogs in and of itself (excluding certain medical conditions) and can be used as a secondary source of protein without harm-- although the studies on this are a bit lacking. \n\nThere are differences between the optimal nutrient balance for dogs and humans, but also some similarities due to the fact that dogs have shared out food throughout their domestication. As far as vitamins and minerals go, dogs (like all species in Carnivora) do not require vitamin C. While (unlike cats) they can synthesize the amino acid taurine, their synthesis is more limited than ours, so it's best if they have some in their diet (especially some breeds). Arginine is considered an essential amino acid in dogs, but not in humans. They also require a slightly higher protein concentration than humans, but not as much as their wild ancestors.\n\nRemember, just like in humans, dogs differ: an Alaskan sled dog or a police K9 are going to need a very different diet than an obese couch Labrador. Certain medical conditions also have special nutritional requirements. The \"optimal mix\" is hard to say globally. If you're interested, [these](_URL_0_) are the AAFCO minimums.\n\nTo answer your other question, \"brain health\" is not a main concern for dogs. Neurovascular disease (strokes) and profound senility do occur in dogs, but nowhere near to the extent that they occur in humans. Neurological problems are rarely the cause of death in dogs. Although, it is true that the symptoms of neurological disease are not as evident in animals as in humans and may go unnoticed by some owners."
]
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"http://www.nap.edu/catalog.php?record_id=10668"
],
[],
[],
[
"http://www.merckvetmanual.com/mvm/htm/bc/tmgn46.htm"
]
] |
|
mzoio
|
what stops people sitting in the emergency exit seats on a plane from pulling the window and killing everyone?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/mzoio/eli5_what_stops_people_sitting_in_the_emergency/
|
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"OK, nobody has explained it yet. \n\nFirst of all, the door is 20-30kgs heavy, and you have to pull it out then turn it and toss it through in an emergency. In the air, the pressure is really high inside the plane, and low outside the plane. This means the air pressure forces the door closed, so you'd never be able to open it.\n\nAs for the ones on the ends that \"open out\", apparently these open in first, then out. So they still have pressure against them. I guess its designed in a way which means as its pulled in, the angle changes slightly. Either way the positive air pressure inside the plane stops the doors from opening in the air",
"OK, nobody has explained it yet. \n\nFirst of all, the door is 20-30kgs heavy, and you have to pull it out then turn it and toss it through in an emergency. In the air, the pressure is really high inside the plane, and low outside the plane. This means the air pressure forces the door closed, so you'd never be able to open it.\n\nAs for the ones on the ends that \"open out\", apparently these open in first, then out. So they still have pressure against them. I guess its designed in a way which means as its pulled in, the angle changes slightly. Either way the positive air pressure inside the plane stops the doors from opening in the air"
]
}
|
[] |
[] |
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[],
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||
6tonty
|
how are deafblind people taught to communicate?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6tonty/eli5_how_are_deafblind_people_taught_to/
|
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"The brain's capacity for *language* is not strictly a sensory function. We may perceive *expressions* of language via our senses, but language is *processed* by entirely different sections of the brain. \n\nThis may seem obvious, but it's important here. A person missing one or more of the five senses need not have any deficit in their *linguistic* capacity whatsoever. Take the alphabet, for instance. The English alphabet is *significantly* phonetic, but anyone studying English as a second language will almost invariably find the English language's tendency to *completely* disregard prevailing phonetic rules in the most promiscuous fashion laughably frustrating. Most other languages with phonetic alphabets have a far stricter correspondence between individual letters and combinations thereof and phonetic sounds than does English.\n\nBut that just underlines the fact that the way a word *sounds* does not have nearly so much connection to what a word *means* and how a word is *spelled* as one might think. One can learn that the word spelled \"D-O-G\" refers to a quadrupedal mammal without ever hearing the word pronounced. . . or seeing a dog. \n\nAs to more \"abstract\" concepts, it would depend upon the kind of abstraction we're talking about. Philosophical concepts would not appear to be any more or less difficult for a deaf/blind person than a hearing/sighted person. Such concepts are, after all, *concepts*. \"Justice\" is not amenable to perception by any of the five senses, so there is no obvious reason to think that a person lacking one or more senses would have any more difficulty grasping the concept than a person possessed of all five. It's only when we get to subjective impressions that are inherently a function of the senses (what philosophers call \"qualia,\" e.g., color, musical pitch, etc.) that someone like Keller would really be at a loss. But it doesn't seem to have slowed her down much. Those subjective impressions, interesting and important as they may be, turn out not to play nearly so much of a role in the way we live our lives as it might seem. ",
"I'm a nurse that works with DeafBlind individuals, hopefully I can explain this well! \n\nFor most things, it's all about teaching the concept behind the idea. And using all other available senses. Also, repetition. \n\nFor an apple, you can sign with AITSL (adapted interactive tactile sign language - hand over hand) the sign for apple. Have them eat an apple, sign it again. Smell apples, sign it again. Feel the apple, sign it again. Etc. \n\nFor more abstract concepts - for example, laundry - seems simple enough. It's easy to teach someone the *skill* of doing laundry, but *why* do we do it. Because things are dirty, of course. But if you cant see the dirt, or get the concept of the clothes being 'dirty', it seems silly as to why we put out clothes in this machine. So we have to start with teaching 'dirty', go I. The garden, get messy, feel/smell the dirt on your clothes. Then teach the concept of clean. Then putting it all together, explaining that the machine takes the clothes from dirty to clean. This is a painstakingly long process, and also relies alot on the DeafBlind individuals cognitive abilities. \n\nAlso, keep in mind, most DeafBlind folks have some residual hearing and vision. One client I support just requires that we sign for her about 2-4 inches right in front of her left eye, as that's where her visual field is. \n\nI hope that helps! \n\nEdit: Gold?!?! Thank you, a hundred times over, kind strangers!! \nAlso I've had a lot of requests for an AMA, I'm totally going to do it, stay tuned! And thank you all for the overwhelming interest in what I have to say!! And especially to OP for asking the question that started all of this awesome dialogue :)",
"Helen Keller's teacher would trace letters and words on Keller's hand with their fingers. \n\nIn one specific instance, the teacher placed a doll in one of Keller's hands, and then traced the letters D-O-L-L on the palm of her other hand. Eventually Keller would communicate \"doll\" back to her teacher.\n\nThis can be expanded upon to include other objects, verbs, and ideas.",
"There is a newer communication system, Protactile, which came from the Deafblind community. It involves signing in a tactile manner, as well as 'backchannelling\", which is tapping on the speaker's body to indicate you are following, like a sighted person would nod or make noises like hmmmm to indicate being engaged in the conversation. This allows persons with Deafblindness to speak directly with one another. An awesome Deafblind writer, John Lee Clark has very interesting pieces on Tumblr, if you are interested in work by someone who lives this experience. ",
"Helen Keller's autobiography covers this fairly well. She was deafblind from a pre-adolescent age and went on to be tremendously successful.\n\nIt's been a long time since i read that but it essentially involved a form of the tactile signing others have explained, plus a lot of repetition and exposure. She gave the example of being taught the signs to spell the word water, and having her hand placed under running water by her teacher. ",
"Hi, have a look @clarissavollmar on Facebook. I belong to the deaf community myself and follow this family. Clarissa is a deaf-blind child and her family documents how they are raising her. It is very interesting to see their experiences and the family is thorough in explaining their challenges.",
"The documentary film by Weiner Herzog called Land of Silence and Darkness is about a woman who is deafblind teaching other deafblinds how to communicate. It is phenomenal. I wept tears of wonder and inspiration at the lengths to which humans are capable of going to help their fellow humans. \n\n_URL_0_\n\n_URL_1_\n\nRent it. So amazing.",
"I'm a Asl interpreter and have only done tactile deaf blind interpreting once. We practiced it in class a few times but very briefly.. it was an amazing experience.. even after learning asl and the movements involved it can still be tough to distinguish a lot of signs when your eyes are closed and \"blind\".. also it makes your arms tired from the client holding your hands and weighing movements down ha.",
"Can we get a deaf or blind or both person to chime in here? AMA?",
"Everyone in this thread is using deafblind as if it's a well-established word and I've literally never heard it used. ",
"Do children who are born deaf Blind have an age requirement where they are developmentally required to start learning some language before they lose the ability? Im guessing any normal parent would start right away. I'm thinking back to Genie, the girl kept in the room and ignored for years, and other stories of \"feral\" children. Since they didn't learn a language by an early age, they were never truly able to communicate.",
"There is a good Bollywood movie on this subject. It's an Indian movie (Hindi) called Black starring Amitabh Bachchan and Rani Mukherjee. \n\nIn the movie they depict very accurately how deaf blind and mute people are trained and the obstacles they face. Worth a watch. \n\nYou could watch it with English subtitles if you don't understand Hindi. \n\n[IMDb link for Black. ](_URL_0_)"
]
}
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[] |
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[],
[],
[],
[],
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"https://en.m.wikipedia.org/wiki/Land_of_Silence_and_Darkness",
"https://youtu.be/bKjokn2tdfU"
],
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[],
[],
[],
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"http://m.imdb.com/title/tt0375611/"
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||
2wwv9f
|
what's the difference between vapor and smoke?
|
I use electronic cigarettes, and the "vapor" they produce looks and behaves exactly like smoke.
But it isn't smoke.
I can't explain it to people who ask me about this "smoke". Sometimes I say that it's like a mini kettle, boiling the cigarette liquid and producing steam - but it isn't a steam so I don't like using that explanation.
So what exactly is vapor?
Thanks.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2wwv9f/eli5_whats_the_difference_between_vapor_and_smoke/
|
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"Have you ever been to a concert or another place that had a fog machine? That fog is created by heating and vaporizing a mixture of water and a non-toxic chemical. Nothing is burned with fire to make that fog, though it appears to be very smoke-like.\n\nThat is similar to how electronic cigarettes work. They are miniature fog machines, to put it in the simplest terms.",
"Vapor is basically just steam that is the same temperature of the surrounding air (which is why it doesn't burn your mouth). Smoke is a byproduct of combustion. It contains a whole bunch of chemicals but very little water.\n\nVapor is cool and mostly water.\nSmoke is hot and has no water.",
"Smoke is a combusted material, for example, Carbon's molecular structure prevents it from being liquid (without extreme pressure), so when the carbon heats up it sublimates from solid into a gas.\n\nVapor is a created when a liquid \"possesses\" energy. I'll use water as an example, water like other liquid will always expand, when you pour water into the glass it spreads out and fills it. So when water \"receives\" energy the particles are able to do a even better job of spreading out. These particles spreading out and becoming suspended in air is vapor.\n\nA good way to tell the difference is to put some smoke in one sealed jar, and vapor in another. After cooling down, the jar with the smoke will have a layer of ash, while the jar of vapor will have condensation. "
]
}
|
[] |
[] |
[
[],
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|
2qw215
|
Why does the sun appear yellow but stars at night appear white? And does the redshift in a stars light due to distance affect the color we see with the naked eye?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2qw215/why_does_the_sun_appear_yellow_but_stars_at_night/
|
{
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"The Sun appears yellow from the Earth's surface mostly because the atmosphere scatters blue light. A bright G-type star like Capella also appears yellowish. Most stars, except some of the brightest ones, appear white because [the photoreceptor cells in our eyes which detect color (cones) require more light than the rods](_URL_0_).\n\nNo, there aren't any stars we can see with enough redshift to make a difference in its apparent color."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Photoreceptor_cell#Difference_between_rods_and_cones"
]
] |
||
38nx5r
|
why are republicans and obama both in support of obamatrade?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/38nx5r/eli5_why_are_republicans_and_obama_both_in/
|
{
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"text": [
"Because it serves American economic interests. Not the American people, necessarily, but corporations definitely. We want to maintain global economic superiority and giving our megacorps more help with this legislation does that. These trade agreements may not help the average person but it makes us more powerful as a country and Obama recognizes that. Same with NSA spying, sort of. Becoming president probably changes your perspective."
]
}
|
[] |
[] |
[
[]
] |
||
8ywen8
|
How does one "shoot" alpha particles at something?
|
I was in chem the other day and we were talking about rutherford's famous experiment and how he shot alpha particles at gold foil. I know what alpha particles are but . . . how do you shoot them?
|
askscience
|
https://www.reddit.com/r/askscience/comments/8ywen8/how_does_one_shoot_alpha_particles_at_something/
|
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"In Rutherford's days (and for simple tabletop experiments today), you just take an alpha source (a material that naturally decays by alpha emission), and collimate it. That means that you surround it with shielding except for the direction in which you want the alpha particles to move.\n\nYou can make your \"beam\" as directional as you want, by making the collimation more or less stringent.\n\nHowever this is very limiting. Each alpha decay is monoenergetic (although the source can undergo more than one decay branch), and alpha decay Q-values tend to be around 5 to 8 MeV.\n\nSo this limits very much the kinds of experiments you can do. Additionally, if you want a high rate, you need a high-activity source, which is difficult to deal with.\n\nNowadays we use accelerators. You can produce a beam of alpha particles which doesn't need to be \"manually\" collimated. You can tune the energy to whatever your accelerator is capable of providing. Accelerators can generally reach energies much higher than typical alpha decay Q-values. And its easier to develop higher-intensity beams, as opposed to just working with an alpha source with a very high activity.",
"The experiment was performed by Hans Geiger and his undergraduate assistant, Ernest Marsden.\n\nWhen they're liberated, the mutual electric repulsion between the helium nucleus and the parent nucleus causes the alpha particle to fly off at about 3%-5% *c.* This is a lot [citation needed.]\n\nThis was sufficient for Geiger's and Marsden's experiment. In fact, additional acceleration wasn't possible, since the first linear accelerator wasn't invented until 1928.\n"
]
}
|
[] |
[] |
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[],
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|
6w0qw5
|
why tattoos do not initiate immune system response?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6w0qw5/eli5_why_tattoos_do_not_initiate_immune_system/
|
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"text": [
"They do (no super cereal though), that's why they fade over time. It's your body \"eating\" the ink and disposing of it. You literally poo out your tattoo.",
"They do. The needle penetrating the skin causes histamine to be produced, thats why the area being worked gets red and swells somewhat. For anything else to happen there need to be antigens present. Those are molecules found for example on bacteria that cause them to stick to certain immune system cells and activate them. The ink molecules are generally too small to do that, though it can happen to some degree. They are so numerous that an actual immune response to them would be harmful to the body anyways. If the needle was unclean, bacteria and other antigens introduced into the tiny wounds will cause an infection and more immune response.",
"This is the reason I can't have tattoo's. See I had a bone marrow transplant, and because of that my immune system is super sensitive. If I had a tattoo, the immune system would turn the area into a leather-like skin that would mess up my tattoo. Which sucks, because I really want one. But hey, its better than being underground.\n\nSo I live through other people's tattoo's. Show them to me and tell me what it means to you. Esp if they are works of art!"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
23fg72
|
Does Post-Modernism make the study of History futile? and if not why not?
|
Maybe I am being naive or overly nihilistic but my study of Post-Modernism especially in relation to history has left we with a sense of hopelessness when looking at History. If we can never truly know the past (an admittedly simplified version of a Post-Modern position) whats use is History beyond being a good story? I would rather believe that we could know the past but it seems clear, and is admitted by many historians, that we can't. Not every academic subject has to be crucial to human progress (I am aware of the irony when I talk of progress and Post-Modernism in the same breath) but the discipline of History certainly has pretensions to this claim. That lessons can be learned from the past seems impossible if we can never know the past? Thanks in advance for any help in my existential malaise.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/23fg72/does_postmodernism_make_the_study_of_history/
|
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"I'm a big fan of postmodernism. It's all very interesting. The thing you have to watch out for, though, is that you don't fall down the rabbit hole. It's easy to get a sense of hopelessness about history because it swipes away the entire basis of what traditional historiography was built upon - that is, that history is a science, with verifiable facts and objective truths. It's not. And that's okay. \n\nThere was an interesting thread a month ago, where the question of why we study history was put forward. [The answer rarely was to map out our past](_URL_0_) or anything like that. I personally prefer the top-voted answer:\n\n > If you think that learning from other people is a worthwhile endeavor, then you should realize that most people are dead now, and you must turn to history to consult them.\nTo me, history isn't necessarily about improving military decisions, or making better political choices. (Though it can inform those things.) It's about understanding who we are and where we came from, and learning from other people about who they were and what they cared about. Learning other ways of doing things can open up new avenues of thought that wouldn't have otherwise occurred to us. It can help us understand and respect other ways of doing things, and to value our own culture and beliefs. And to me, that's worthwhile.\n\nRelated to this is the thought that history is essentially the study of humanity. It's an identity-forming process. We project ourselves onto the past and study our own reflection - this in itself is a realisation we got from postmodernism. And by looking at ourselves, we don't just learn more about ourselves, but we form an identity as well. History is at the same time a mirror and a canvas on which we paint ourselves.\n\nIt seems to me that your existential crisis is about the methodology of history, instead of about its purpose. Because, in some way, you still hold on to the traditional purpose of history and now that postmodernism has undermined the traditional methodology that goes with it, you feel lost. But you'll find that postmodern methodology goes best with a postmodern purpose of history - it may be the one I outlined here, it may be one you find yourself. In any case, there's no need to despair yet. History still has value.",
"I have a thorough dislike of postmodernism; it is too extreme for me. Postmodernism basically does away with the idea that language reflects reality. If language is indeterminate, if we can't be sure what it refers to (if anything), if all we do with language is construct our own reality - then language would be useless. We know from experience that it isn't. John Tosh in *The Pursuit of History* puts it like this:\n > Historians frequently acknowledge that they cannot fathom all the levels of meaning contained in their documents. But to maintain that *no* text from the past can be read as an accurate reflection of something outside itself flies in the face of common experience. In a set of trade figures or a census return the relation between text and reality is palpable (which is not to say that it is necessarily accurate). A carefully considered literary production such as an autobiography or a political tract disguised as a sermon presents much more complex problems, but it is still important to recognize that their authors were attempting a real engagement with their readers, and to get as close as we can to the spirit of that engagement.\n\nFurthermore, the postmodernist denial of (knowledge of) causality of events is too extreme for me. I accept that causality in history is not as clear-cut as causality in physics, but I would not dismiss every attempt at identifying causality as mere interpretation. In at least some cases we certainly can say that some event A contributed to some event B happening. Would B have happened without A? Who knows. If something like A happens again, will something like B happen again? Probably not. But damn me if A didn't contribute to B happening. \n\nAll that said, what I would agree with, is that it is impossible to get to 'The Truth' in history. There is so much from history that is lost to us that we can never get a complete and accurate view of history. Because our view is at best fragmentary, any Rankean attempt at history is doomed to fail. As has been said by others, history's benefit to us is mostly limited to gaining an understanding of ourselves and our society.",
"I've also struggled with the question you are posing and I've come to the conclusion that the value of history is not tied to an absolute all-encompassing understanding or knowledge of the past. Here's my answer to this question.\n\nThe hardest part about it is that you're right. We can never know all of the past, and even if we did, we couldn't possibly communicate the totality of that experience. As far as we know the only thing that can process the complexity and enormity of human experience are humans themselves. A book, no matter how well written and detailed, is only a pale shade of living experience. A book detailing every experience of a single individual is still too much for a reader to absorb or appreciate. Imagine trying to write about a family of individuals? Or something believed by a dozen individuals? A government formed by hundreds to govern thousands or millions? The effort scales far far off the radar of human capability if we were to try to recreate the past as accurately as possible.\n\nSo first we must accept the impossibility of our task comes from physical limitations as much as existential crises about knowledge. Let's say that we invent a device that does communicate the totality of experience to another individual. Some sort of mind-downloader that lets us live the uniqueness of another human's experience. We've overcome the physical barrier to communicating the whole of the past. We are still confronted by the problem of subjective experience and constructions.\n\nLet's look at an example. You and your friend listen to Bob Dylan's \"The Times They Are A-Changin\" for the first time. You are immediately struck by the lines, \"Come mothers and fathers / Throughout the land / And don't criticize / What you can't understand / Your sons and your daughters / Are beyond your command.\" Your parents had tried to control you in your late teenage years and this line makes you remember walking out of the house at 17 to live your own life. You feel happy and triumphant.\n\nUsing the mind-downloader, you live your friend's experience of the song. For your friend, every time Dylan says \"for the times they are a-changin,\" they are racked by an even stronger emotional response. Fear, anxiety, sadness. Dylan's song isn't an expression of freedom, but a lament for an ever-changing world that will never - that can never - be the same.\n\nWhich of these two experiences is more true? Is one wrong or right given what Dylan intended the song to mean? Does it matter that one is a deeper emotion or a more shallow one? Does the commonness of your experience make it more or less valuable than the somewhat unique response of your friend? \n\nThese are not the sort of questions historians ask about the past. They are not ones that weigh the value of past events and individuals in relation to their accuracy, to their impact on others, and to what was known at the time. In short, historians examine accuracy, effect and uniqueness. Accuracy, you might say, sounds like truth, but I think there's a key distinction between asking the truth of a fact compared to the truth of the past. While examining historical sources, historians are charged with asking: Can we confirm this information? And in turn, what effect did it have? Is it a unique or common experience/source/idea? \n\n\"Is it true?\" is not a question we seriously ask anymore. \n\nTruth is relative after all. Bob Dylan's song is a thousand things to a thousand people. It can be an inspiration or a depressing reminder. You could list its sales and the money it made and it becomes a statistic which is more meaningful to some and less meaningful to others. As post-modernists suggest, despite the feeling that one might be more 'true' or 'worthwhile' than the other, both are entirely constructed. We like to imagine that the value of past experience takes a one-way street going from Point A in the past (when it occurred) to Point B in the present (when we realise its value), but it's the reverse. We impose value onto the past. We impose value on everything! That's the crux of the existential crisis that nothing has value but what we make up for it.\n\nAnd that's the beauty of history. It is nothing more than the stories we tell about ourselves and only has value to storyteller and audience. From your parents telling the story of how they met for the hundredth time, to your friend's story about that one time he saw a flying pig, to the time your hometown chef won that chili cook-off in the county over, to the nation that fought the just war against fascism. As Canadian writer Thomas King says: The truth about stories is that's all we are. \n\nIn the quiet of your mind, ask yourself: who are you? Why are you the person that you are? The answer is probably a whole lot of stories about yourself whether you know it or not. You don't like broccoli because of that one time the dog threw it up. You fell in love because you had to buy flour at 2:09am. You like the summer heat because you don't like socks. You don't like socks because you like summer heat. You cry during Bob Dylan \"The Times They Are A-Changing\" because of all the times that changed and you weren't ready for it.\n\nThese stories are the most valuable thing about who you are. They make you who you are. Without them, you are a blank slate, an empty vessel devoid of the complex, messy, amazing individual experiences that makes us human. A person without a past is hardly a person at all.\n\nAs human gathered to form communities, they naturally did the same with their communal past experience. Just as we make up value for our own individual past experience, we began placing value on our shared experiences. The history of a villages, of kingdoms, of nations, all naturally emerges as a result of humans telling the stories of who they are. We collectively attach value onto experiences to tell the story of Canada, or of women, or the French Revolution, or of 19th century British working class families. Instead of dogs throwing up, late night flour purchases, or sockless summer days, we talk of bravery during war or grave meetings in tennis courts or the decisions of the impoverished during desperate times. \n\nThough all experience and historical \"truth\" is relative to perspective, that does not diminish the worth of each of those perspectives. Sure, history is formed by constructions of society and linguistics, just look at gender, or race, or political and economic systems. They are ways for humans to try to make sense of the world. But so are the stories we tell about ourselves. I saw a dog throw up cake too, but I still eat cake and don't tell that story to anyone. I don't cry during Dylan songs, but I think about it. The story is better if I cry though. Close enough, right? \n\nYes lessons can be learned from these stories. We can remember things like don't eat broccoli, or don't invade Russia in winter, or always know times are a-changin'. Historians providing lessons from the past isn't really why the profession of history is worthwhile though. Like so many content-creators, we are artists. In the cacophony of infinite human experience that is the past, historians transcribe a single voice from the white noise. Or a chorus of voices or a symphony of sound. Limited as we may be by poor recordings or distorted notes, historians take the complex and make it simple. We overcome the physical impossibility of communicating the past as best we can. We are not composers but conductors, or as French historian Marc Bloch might say, not lawyers but witnesses - we do not create or indict, but we organize and observe. To use one of my favourite quotes about our profession from Johann Droysen in 1868: \n\n > History is humanity's knowledge about itself, its certainty about itself. It is not 'the light and the truth,' but a search thereof, a sermon thereupon, a consecration thereto. It is, like John the Baptist, 'not the light but sent to bear witness to that Light.\n\nOur duty is not to speak of truth. We bear witness to the great endeavour of human existence, we worry about the accuracy, effect, and uniqueness of our stories, not the truth of them. The only truth about history is that it is all we are. The historian's task is to search and communicate the answer to that question: Who are we? Describing who we are - all of us, not just the rich white guys who wrote so many books - that is the historians' task. It is the truth and the answer for which we will always search but we will never find. Or as Droysen says, \"It is not 'the light and the truth,' but a search thereof, a sermon thereupon, a consecration thereto.\"\n\nEdit: [I turned this into a posting on my blog, which you might enjoy if you liked this post.](_URL_0_) ",
"You're not alone in what you're going through - I've spent years wrestling with these questions, as has most of the rest of my PhD cohort. You can come out the other side if you keep pushing forward! :)\n\nLike many of the other commenters here, I've come to appreciate postmodernism more and more as I understand its implications better. It does kill the kind of certainty we wanted to find in the past when we first started studying history, but once you get past the nihilistic despair that inevitably accompanies that realization, a lot of exciting possibilities open up. Postmodern historians can never hope to write the True History of All Things, but that's ok because we can do other things that (I think) are much more interesting.\n\nPostmodernism boils down to the proposition that everything's a story - 'facts' are constructed, and are then woven together into narratives by people, power structures, discourses, etc. But at their root, they're all just competing stories about how the world is, and we - living today - get to build our world out of the stories that we're told and the stories that we write about the world now. As historians, we've chosen to write stories for the present based on the past, and to do it in such a way that the past can be allowed to come to life and change us and the way we think about the world. We open ourselves up to old stories, and we see where those stories take us, and how we can arrange them to make sense of them and the world they came from.\n\nAn example. Late antique (the end of the Roman empire) historians studying the 'barbarians' who migrated into the western Roman empire would pull out a late Roman historian (like Ammianus), find all the references to the barbarians, and treat these as 'facts' to be reassembled into a comprehensive history of What Happened (for an example of this, look at H. Wolfram's *History of the Goths*, 1980). The 'facts' might be biased or inaccurate, so historians of this school tried to sort them into good and bad pieces of data, but in the end, the idea was that they could be cut out of their original sources and sewn back together into a thick, Frankenstein's-monster-esque summary of the data.\n\nPostmodernism has completely changed this by causing historians of this period to see their sources, first and foremost, as literary works - as stories, complete with plots, themes, literary structures, and complex agendas. You can't chop up a work of literature for 'facts' without first considering how all of its pieces fit together in the larger structure that the author was building to make his larger point (if you pull out the facts you want without considering their context, you're likely to miss the reasons the author put them there, and without understanding those reasons, you can't really understand why the author constructed these 'facts' the way he did). So, instead of writing massive compilations and analyses of data, historians of this material are now looking at the stories late antique authors were telling in their contexts, and using this to write a better story for ourselves about their world.\n\nThe results are both more interesting, and more in line with the nature of the historical data itself. Because most of the texts historians use aren't data - they're stories. And when we treat stories as data, we're pushing them into a box that limits and distorts what we can get out of them, and what they can say to us. Postmodernism frees us to read things as stories instead of facts, and this has (at least in my field: late antiquity / early middle ages) opened a wealth of new avenues for fantastic scholarship.\n\nAnd in the end, we base our stories about the past on evidence, and that evidence speaks with its own voice. It will change and challenge our perspectives if we pay enough attention to it. That's what keeps us from writing pure fiction, and it's what makes the task worth continuing."
]
}
|
[] |
[] |
[
[
"http://www.reddit.com/r/AskHistorians/comments/200ru9/why_do_we_study_history_i_am_at_a_loss/"
],
[],
[
"http://clioscurrent.com/blog/2014/4/24/2cwscwvtpzrwflzmxq2e3job7r0unr"
],
[]
] |
|
7vgrdj
|
before computer databases, how did states keep track of which license plates they already issued?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/7vgrdj/eli5_before_computer_databases_how_did_states/
|
{
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"Well, they used old fashioned paper databases. That's how the world worked before computers were introduced. ",
" > Remember, I’m 5 and don’t know how paper files work.\n\nBut you know what a computer database does???\n\nThey wrote down the license plate numbers and info on paper, and organized them in cabinets."
]
}
|
[] |
[] |
[
[],
[]
] |
|
3cxf5m
|
what does bernie sanders stand for and why should i vote for him.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/3cxf5m/eli5_what_does_bernie_sanders_stand_for_and_why/
|
{
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"text": [
"You should take a look at [ISideWith](_URL_0_), as it will answer your question much easier and more completely than most of us might be able to.\n\nIt's a simple quiz that(make sure you click the \"Show X More\" options in each section), at the end, will tell you how much you agree with each political party and candidates, and gives you a breakdown of what issues you agree/disagree with for a given candidate. ",
"That's a pretty large answer. I'd encourage you to visit /r/sandersforpresident for some more thorough answers, but here's a brief rundown:\n\n--Universal, single-payer healthcare for everyone.\n\n--Removing the influence of money in politics, partially by getting Citizens United overturned.\n\n--Pro gay marriage (not that that's an issue anymore).\n\n--He's big on trying to reduce our impact in terms of climate change.\n\nThere are, of course, others--but again, I encourage you to do some research into it from various different sources.\n\nBut why should you vote for him? If you agree with his positions, that's one reason. But even though I agree with most of his positions, that's not the reason I personally support him. The real reason is that *he's an honest politician,* unlike any I've ever seen. He has a 30 year record of putting his money where his mouth is, of *not* being evasive or disingenuous when he's speaking, and of clearly supporting or clearly opposing whatever his stance on the issue is--unlike most politicians, he doesn't appear to be trying to get as much money as he can from any source he can. That's huge."
]
}
|
[] |
[] |
[
[
"http://www.isidewith.com/elections/2016-presidential-quiz"
],
[]
] |
||
8dvpq7
|
How does sunscreen stop you from getting burnt?
|
Is there something in sunscreen that stops your skin from burning? How is it different from other creams etc?
|
askscience
|
https://www.reddit.com/r/askscience/comments/8dvpq7/how_does_sunscreen_stop_you_from_getting_burnt/
|
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"Yeah it contains one or more ingredients that absorb or reflect UV radiation very effectively. So while sunscreen usually doesn't change how you look in the visible spectrum, at least not much, if you had UV vision it would look like being smeared in paint.\n\nThe active ingredients can vary. Generally organic compounds tend to absorb the UV, while inorganic compounds like titanium dioxide tend to reflect and scatter it away.",
"There are two primary ingredients to sunscreen. Inorganic semiconductors particles and organic molecules. Small particles of semiconductors with bandgaps of around 400nm such as TiO2 \\(381nm/413nm\\) and ZnO \\(376nm\\) either scatter or absorb incident UV radiation. Scattering means that the amount of UV radiation making it to your skin is reduced by scattering it away from you, small particles are very good at this. Basically it makes you a frosted UV mirror. Absorption pushes electrons into higher energy states, those electrons then thermally relax back to their ground state by releasing multiple low energy photons \\(heat\\). The analogy is taking an elevator to the top floor and then going down the stairs rather than jumping out the window \\(many small harmless steps rather than one big and harmful jump\\). Organic absorbers, such as avobenzone or oxybenzone, work in the same way; by absorbing high energy UV radiation \\(nasty cancer causing stuff\\) and releasing it as relatively harmless heat. ",
"Great question that has two answers, depending on the kind of sunscreen we're addressing. For starters, there are two types of sunscreens: physical sunscreens and chemical sunscreens. \n\nPhysical sunscreens are chemically inert products that reflect or scatter radiation: therefore, they help stop burns by 'bouncing the rays' right off of your skin. These agents are typically more broad-spectrum that chemical sunscreens, meaning they simultaneously block UVA (which penetrates the skin deeper/is linked to wrinkling) and UVB (which burns the skin/causes DNA damage). The most common types of physical sunscreens are zinc oxide and titanium dioxide. \n\nChemical sunscreens are aromatic (ring-shaped) compounds that absorb radiation and convert it into wavelengths that are longer and lower-energy. By doing so, you 'slow down' the wavelengths that typically cause skin to develop a burn. These chemicals are not typically broad-spectrum, meaning that some are better at blocking either UVA or UVB; therefore, combinations of different chemical sunscreens allow you to create a \"broad-spectrum sunscreen\". \n\nSunscreen is super important, and everyone should be wearing it! Protect your skin out there!",
"In addition to the other correct responses, I want to explicitly point out that a sunburn is a radiation injury, not an injury due to thermal transfer. You are not cooking like food in a conventional oven or when you burn yourself with a flame.\n\n\n > Sunburns differ significantly from thermal burns, which result from infrared radiation. Although infrared radiation gives sunlight its warmth, it is not the heat of the sun that burns skin. \n\n\n\n\n\n > The energy from ultraviolet radiation can damage molecules in the skin, most importantly DNA. One consequence of this is the synthesis of different proteins and enzymes. The effects of these proteins, notably prostaglandins and cytokines, lead to dilation of the cutaneous blood vessels and recruitment of inflammatory cells. This, in turn, produces a sunburn's characteristic redness, swelling and pain.\n\n\n[Source](_URL_0_)\n\n\n\nEdit: clarified some wording to increase clarity and accuracy and added source",
"Titanium dioxide (white pigment) and benzephenone (A UV photo initiator). They absorb/reflect UV wavelengths of light and make the sunscreen layer on your skin mostly opaque to UV light, shielding your skin from the harmful wavelengths.\n\nThese are common raw materials used in both ink and sunscreen. Yes sunscreen contains the same materials as UV printing ink, have fun with that knowledge. ",
"Just like water absorbs the microwaves in a microwave oven. Suncream has a compound which absorbs the UV rays in sunlight. This prevents them from penetrating deeper into your skin which damages the deeper, more important cells. This is the same thing that melanin, the pigment in dark skin, does. Conjecture: the energy either breaks the compound meaning it gets used up (likely for suncream) or the compound just gets hot but is in an environment which is resistant to heat and a poor conductor so the heat is contained (likely for melanin) ",
"To add some more information about sunscreen, SPF is measured by how long it takes UV radiation to change the tone of skin. It is a logarathmic scale, so SPF 50 doesn't absorb twice as much as SPF 25, rather they both absorb over 90% of UVB radiation. 50 will just be on the higher end of the 90s.",
"There are 2 camps of sunscreens. Mineral and chemical. There are also mixes, but they may as well just be chemical.\n\nMineral sunscreens reflect uv away from the skin from the surface. (no uv penetration)\n\nChemical sunscreens absorb into the skin and then absorb the uv light before it is able to penetrate too deep via a chemical reaction. The result of this reaction is heat that is dissapated into the skin. ",
"There are two types of UV light, and they affect your skin in different ways. In general UVA affects aging as it penetrates deeper into the skin and can affect the cells of your skin causing DNA damage and UVB is what actually causes your skin to burn even though it doesn't go quite as deep through the breakdown of the structural components of skin. \n\nFor UVA you need to stop it from penetrating so deeply. Certain chemicals in suscreen Oxybenzone and Parabenzone as an example absorb UVA rays. They do this by virtue of their structure as aromatic ketones. When the UV light hits them, it has similiar energy as one of the bonds and absorbs most of it's energy: seen [here](_URL_0_)\n\n(side note, when they say aromatic, they mean it, aromatic compounds are used in a variety of perfumes and artifical aromas, and in this case it has the side effect of giving sunscreen it's unique smell)\n\nFor UVB and UVA you need to reflect it away from the skin entirely, metal oxides are pretty good at that specifically Zinc Oxide and Titanium Dioxide. These are pretty good for blocking and reflecting UVA as well. One chemical you can use to block UVA/B but isin't commonly used anymore because some people were allergic to it is Paraaminobenzoic acid (PABA)"
]
}
|
[] |
[] |
[
[],
[],
[],
[
"https://www.scientificamerican.com/article/what-happens-when-you-get/"
],
[],
[],
[],
[],
[
"https://1.bp.blogspot.com/-3UQncBh44Zs/ULEsJj_wjlI/AAAAAAAAEoU/FEBu6v0czp4/s1600/Picture4.png"
]
] |
|
22g474
|
why do websites bother having the age date range from the 1800s to present day?
|
Because a newborn baby wouldn't be registering plus it's really unlikely that the oldest people in the world would be either.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/22g474/eli5_why_do_websites_bother_having_the_age_date/
|
{
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"Because its not very hard (like literally a few button presses) to expand the range. By covering the entire length of options they can't possibly miss anyone. Much easier than having someone complain saying \"I was born in 1899 and that's not an option\".",
"Grizzled/bitter developer here, and there are multiple answers.\n\n*Because the developer is inexperienced/lazy \n*Because this particular date value isn't important so who cares \n*Because you have to deploy 3 other pieces of code today, all without testing so you don't have time to add fiddly refinements \n*Because it is cheaper to fix things only if people complain and otherwise leave them alone \n*Because you are feeling vindictive today so you set it up so they can fill in the whole page, and then if they put in fake data (you are not 4 years old sir) you wipe all their input and throw a big red error message. \n\n\n\n"
]
}
|
[] |
[] |
[
[],
[]
] |
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