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Why is it that you can tell if someone has down syndrome just by the way they look? What is causing them them to look so similar to one another ?
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[
"Down's Syndrome is caused by an extra copy of Chromosome 21. This leads to a common set of facial features and other traits."
] |
[
"Imagine you are made of genetic soup. Some people have ingredients that just don't go well together and make the soup taste bad. But that's ok, because when you have a kid, we just take some of my soup and some of my wife's soup and pour it in together. So even though my soup has some bad ingredients, her ingredients can cancel them out - and some of my ingredients can cancel out her bad ingredients. But what if I had a kid with my sister? She has all the same bad ingredients I do (because we were made from the same batch) and so the soup will taste just as bad if not worse. Now imagine that for generations, my family has just been reusing the same ingredients time and time again. That soup is going to be awful."
] |
How does someone start a business?
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[
"1. An idea. 2. Business Plan 3. ??? 4. Take the plunge 5. After some years: profit"
] |
[
"This CGP Grey video does a really good job of explaining it all. _URL_3_"
] |
Was Arab slave trade worse than the atlantic slave trade? If so, why are we not taught about it?
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[
"Arab Slave trade is taught in our history classes, being Nigerian we start with the Trans-Saharan trade, its routes and its impacts when we get to Nigerian external relations topic. As to why its not discussed more publicly: * Firstly, the Trans-Saharan trade in general quickly loses importance in the eyes of the city state state actors with the dawn of the trans-Atlantic trade, the Europeans simply had more things the rulers wanted and the guns which they brought arguably had more of an impact than the muskets and horses which were the main trade items of the Trans-Saharan trade. * Secondly, more slaves were transported via ships, simply ships could take more. I cannot comment on the lack of conversation about it in the \"modern\" Europe/US on this sub. Rules and all."
] |
[
"It looks like it's different editions of the same book. The first book you linked is the [US paperback edition](_URL_1_), the second book is the [UK ebook edition](_URL_3_). There's also an [UK paperback edition](_URL_0_) and a [US ebook edition](_URL_2_). It is not unusual for there to be a slight delay between editions in the US and the UK. I quite liked the book btw, though I'm no expert on the crusades so I can't say with any confidence how accurate it is (it's pretty good though, as I've understood from others)."
] |
Why does heat alter our perception and create a "wavy" effect.
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[
"Heat changes the refractive index of air (due to expansion), and as currents and eddies of air pass through a heater – or over a desert – there's an uneven heating effect, causing slight but visible waves of differing refraction."
] |
[
"One way to think about waves is [Huygens' principle](_URL_1_), which states that waves travel as though each point on the wave were emitting an outward-going wave of its own. It's mathematically equivalent to other ways of thinking about waves but is useful for thinking about diffraction. From the Huygens point of view, when a wave encounters a barrier, the points on the wave that make it through the barrier just continue emitting waves. The points on the edges of the opening emit waves radially outward, therefore some bit of the wave must bend when it encounters a barrier. [Here's a picture.](_URL_0_)"
] |
Why can people sell pictures and tshirts of copyrighted characters but not books or movies?
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[
"The books and movies probably get more popular than the t-shirts. The copyright owner is not going to bother unless the person infringing on their copyright starts making significant money."
] |
[
"There's not really a loss from that, there's just less of a gain. If the cost to make a medium shirt is $20, less than $2 of that is actually in the materials of the shirt. Probably even less than that. The rest of the cost is the machinery, the workers' wages, the rent on the factory, insurance, and a dozen other costs of running a business. So at the end of the day, if an XXL shirt costs an extra $1 of fabric to make, there's not really much difference in the final cost. Especially since you'll be selling that shirt for $30 and making a profit either way."
] |
Why do they show flashes of someone's skeleton when being electrocuted in cartoons?
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[
"Doesn't happen to people in real life, no. I always assumed that the cartoon version was a joke along the lines of turning the person into a light bulb and showing the bright bones like the filament of the light, glowing brightly."
] |
[
"To get shorted you must be an active part of the circuit. In particular, you should close to ground. On a wire, imagine there is current flowing. A bird on the wire is actually a resistor in parallel to an (almost) zero resistance resistor, which is the wire itself. The resistance of the bird is immensely higher than that of the wire, so current actually flows on the wire, ignoring the higher resistance path through the bird"
] |
Why does Disney put their movies "in the vault" so that you can't buy or watch them?
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"They are trying to create artificial scarcity. The reasoning is that when they take movies out of the vault for some new special edition anniversary remastered release, people will know it is a time limited offer, and be willing to spend more to own it. Whereas if it is always available, people will put off purchasing it, wait for discounts, that sort of things. Of course, this would probably work better in a world where it isn't so easy to procure movies via less honourable means."
] |
[
"I'm afraid real life is less exciting than the Da Vinci Code. Wikipedia gives you the right answer to both questions. The Vatican Library has a wonderfully important collection of historical texts, that they encourage qualified scholars to visit. It isn't keeping anything hidden. The unfortunately named secret archive contains mostly state papers. Qualified scholars are also invited to apply for access to the archives."
] |
Does alcohol consumption severely inhibit muscle growth or is this pseudoscience?
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[
"It's main claims, decrease in protein synthesis and decrease in testosterone, appear to be supported only in cases of acute alcohol intake (getting DRUNK), or chronic alcohol abuse (long term). _URL_2_ _URL_1_ _URL_0_ One small study found an increase in testosterone after moderate alcohol intake: _URL_3_ Moderate alcohol intake would likely not have a noticeable effect, especially for the casual athlete. If you're high-level, hardcore into bodybuilding, maybe it would matter."
] |
[
"That's due to [a 1984 law](_URL_0_) that tied federal highway funding to a drinking age of at least 21. States which set a lower minimum drinking age would lose 10% of federal highway funding. Personally, I think it sucks (especially with [Pennsylvania's *really* tough liquor laws](_URL_1_)), but even those are [slowly getting better.](_URL_2_)"
] |
So how did cowboys make coffee in the American west?
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[
"I'm hesitant to post this, because I have no idea how to find, or even if academic sources exist for something like this. If pressed, I would point to Civil War memoirs, such as Billings' appropriately named *Hardtack & Coffee*. Basically, if you don't mind having grounds settle to the bottom of your coffee, you can make it with a pot or a \"boiler\" or even a tin cup. It's not much more complicated than boiling water and adding coffee. During the Civil War, coffee was mostly issued to the soldiers pre-ground, often with sugar already added to it. I would assume (always a dangerous thing) that cowboys ground their coffee before going out on the range."
] |
[
"[Here is a link to an earlier thread](_URL_0_) that does a good job of answering this question. That thread was also inspired by the exact same Mad Men scene and the top answer briefly touches on the 'crying Italian guy in redface', so it should be the exact kind of information you're looking for."
] |
How do we know how long light has been traveling from a star until it reaches earth?
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[
"We know because we know the speed of light, and we can measure how far away the star is using a technique called [parallax](_URL_6_). Distance / Speed = Time"
] |
[
"Scientist would probably start sending radio waves in that direction. That is all that could be done as we have not hope to do anything else."
] |
ELIT: What is the deal with the MPAA and reddit?
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"MPAA send a request to google to stop showing results for a specific subreddit, /r/FullLengthFilms, because in it they found links to cam recordings of Tom Cruise's newest film 'Edge of Tomorrow'. That subreddit had like, 300 subscribers prior to this but this move made a huge number of people visit it."
] |
[
"We certainly haven't *intentionally* taken any stance regarding this, but we have had some turnover in the mod-team and, being people*, each individual does tend to moderate differently from others. That said, if you see something in a thread you think should be removed, don't hesitate to hit the \"report\" button or [send us a mod-mail](_URL_0_) and we'll take a look at it. \\* Or so they say."
] |
How does dust and debris leave the lungs after it has been inhaled?
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[
"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Does all the dust and dirt we breathe in during our lives just build up in our lungs? ](_URL_1_) ^(_48 comments_) 1. [ELI5 : What happens to objects that you breathe into your lungs? ](_URL_0_) ^(_13 comments_) 1. [ELI5: How does the lung get rid of all the dust particles, flakes and small hairs/threads we breathe on a daily basis? ](_URL_4_) ^(_ > 100 comments_) 1. [ELI5: I clean about 2 pounds of dust from my room every month. What does this means for my lungs ? ](_URL_2_) ^(_27 comments_) 1. [ElI5: How our lungs prevent/eliminate dust ? ](_URL_3_) ^(_32 comments_) 1. [ELI5: do hairs and dust ever get into our lungs? And if so what does our body do about it? ](_URL_6_) ^(_29 comments_) 1. [When you inhale dust, is it stuck in your lungs forever? ](_URL_5_) ^(_2 comments_) 1. [ELI5: How the body removes particles that you inhale, such as metal dust when grinding. ](_URL_7_) ^(_4 comments_)"
] |
[
"Mint and menthol are sensed in the body by special sensory receptors (cold receptors, TRPM8) very much like how spicy food taste spicy (TRPV1). Wasabi produces a similar effect but it's due to the noxious chemical/extreme cold receptor TRPA1. You have those receptors in your mouth and nose (and eyes). Those receptors go to the brain and tells the brain to constrict the blood vessels in your nose/sinus and thus your nose is cleared. Nasal decongestants act to directly constrict the blood vessels without signals from your brain. So basically anything that causes your blood vessels to constrict will clear your nose. Manure probably triggers one of those receptors. I'm not sure which chemical in manure creates that effect edit: I know I threw in a little /r/askscience in there with my explanation, but that's for the curious people to research. You can totally ignore the official receptor names for eli5"
] |
Would being in zero gravity affect your digestive system?
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[
"It's mainly muscles. For example, if you hang upside down, you can still swallow and move food through your digestive system; gravity is merely a bonus force that can help out your muscles. However, it is entirely unnecessary."
] |
[
"The International Space Station uses ~~lithium hydroxide~~ zeolite to scrub CO₂ by ~~chemical reaction/absorption~~ adsorption, and the ~~chemical~~ zeolite can then be regenerated by heat. The equipment is called the Carbon Dioxide Removal Assembly (CDRA). *edit: zeolite not LiOH per /u/RuNaa's comment below."
] |
21st century Confederate pride. Please illuminate this confused Canadian.
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[
"American Southern here. Confederate Pride is a hodge-podge of different concepts. Some of it really is white-superiority wrapped up in a different term. However, the \"Deep South\" is a different place entirely than, say, New England or California. It's slower and more relaxed. There's more of an emphasis on \"personal responsibility\", \"hard work\" and religion. Everything is a little more personal, but everyone also puts a little more of a friendly face (aside from the occasional gunning down a minority for playing music too loud). The South sees themselves not as founded on slavery, but on the principles of freedom. It's \"Middle America\". God, Country, Spirit, Family, Freedom, Blah Blah Blah. Everything in caps, not because we're yelling, but because we care just that damned much. Don't get me wrong, it's all bullshit. But it's pride in a different culture, regardless of how accurate the *self-perception* of that culture may be. Frankly, when you're proud of a \"culture\" you've already taken a wrong turn."
] |
[
"I'll be honest, it's *VERY* hard to explain this situation shortly as it's a pot that has been boiling for over 20 years. I'd recommend spending a couple minutes reading this amazing and well-written response in another thread in /r/OutOfTheLoop _URL_0_"
] |
Question on Time Dilation
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"You've discovered [the twin paradox](_URL_0_). The answer is that you can't have the spaceships \"suddenly\" be at rest with each other. Either one or both must undergo acceleration. In the case of one spaceship accelerating and becoming at rest with the other, the accelerating spaceship has its time dilated. If they both accelerate at the same rate to reach the same frame of reference, then neither's time is dilated - symmetry is conserved. In the case that the spaceships never attempt to reach the same frame of reference, _both_ views are valid."
] |
[
"You seem to be describing a variant of the [ladder paradox](_URL_0_), just using a train and tunnel instead of a ladder and a garage, he he. > What does the outside observer see? The outside observer sees the front guillotine make a cut, then later after the train has passed further through the tunnel, the back guillotine make a cut. The events that are simultaneous for the train passenger are not simultaneous for the outside observer. You can read more about the resolution on the Wiki article I linked to above. Cheers!"
] |
The key differences between the general term of Socialism and Marixian Socialism
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"It may be a mistake of terms, however there really is not such thing as 'Marxian Socialism' and even then Socialism is 'Marxian' (the correct term is usually Marxist) I think you may, and please let me know, but you may be confusing socialism for liberal socialism and marxian socialism for just regular old socialism."
] |
[
"The species in question are all social species. That's what makes the big difference. If a species isn't social it won't have deep instincts to interact with its own species, let alone having that transfer over to other species. Also, regarding the bird example, it is more common than you think. In the wild [many bird species form multispecies flocks](_URL_0_), and some of these are highly stable."
] |
Sunday as the first day of the week instead of Monday
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[
"First off, weekday number is arbitrary. Weeks don't evenly divide months or years, so numbering the days of the week is just a convenience. There is a lot of tradition coming from the Jewish Torah (and its inclusion in the Christian Bible) about the numbering of the days of the week based in its depiction of the six days during which God supposedly created the universe and the seventh day on which he rested. This tradition marked Sunday as the first day of the week in most western Christian traditions. This tradition continues in North America. I'm not sure when it changed in western Europe, but Monday was officially defined as the first day of the week in ISO8601."
] |
[
"That has been done by Congress. The US officially switched in the 1970s. It did not stick. Those industries like the Sciences where it is much more useful switched, but general society where there is virtually no difference in the usages as we do not need to be that accurate in things there is not enough of a benefit to overcome the inertia of learned behavior and the cost of changing the infrastructure. To switch we would have to replace every piece of equipment in every home and building from the screws and nails used to build things, to the pipes in your walls, to the car that you drive. You would have to replace every single road sign in the nation. Etc. It would cost trillions of dollars. Most nations that switched did so before there was a lot of infrastructure or standardization of how things were made or built. Those that switched later like the UK are in a kind of half transition because of those same inertia issues. The UK still uses miles, and still uses Stones and pounds for weight."
] |
Why are there .zips and .rars if they serve the same purpose? Why not just one extension/program?
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[
"The rar format: * Is more efficient than .zip (the compressed file is generally smaller). * Supports some extra features (split files, password protection…). * Is \"secret\", and it's illegal to make new programs that support the format. And regarding the xkcd /u/Kitworks links: rar is not, by any means, a standard. It's like an anti-standard, or a pseudo-standard. The point of a standard is to make everyone do things the same way (users, developers…). The point of .rar is *to force everyone to use the program*. Generally, when someone wants to share an archive to basic Windows users, they will use rar. But if they care about the moral implications, they will use a zip. They could also use 7z (it's equal if not better than rar, and WinRAR supports it with no problem), but it looks \"less familiar\", and may not be recognized as a \"safe file\" at first glance."
] |
[
"Imagine you want to cook some food. You reach for a recipe book. Not being very brave you go for something simple. You take the eggs and mushrooms and butter and ham out of the fridge, and you follow the instructions carefully. At the end of the process you enjoy your omelette and think \"if I ever want this omelette again, I'll go back to that recipe\". Files on your computer are recipes for software to use to do things: show images on your screen, play music out of your speakers, show video and play the soundtrack, help your spreadsheet software fill in some data, and so on. Each file format is a recipe originally intended for a piece of software to persist data between program executions, and some file formats became \"open\" in a certain sense and useable by many pieces of software - e.g. JPEG, MP3 and so on - and some file formats are specifically designed to ensure interoperability (e.g. OpenDoc format)."
] |
Wouldn't the bacteria that hand sanitizer leaves behind just multiply back to the quantity it was before?
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[
"Antibiotics kill by making the bacteria \"sick\". Those that are immune or strong enough to recover pass on those traits. Sanitizers and disinfectants kill bacteria by chemically damaging their cell membranes. Anything that comes into contact with it is damaged and killed. Those that are \"left behind\" as you say did not come into contact with the chemicals. They did not resist the chemicals so there is not trait of being stronger to pass on."
] |
[
"California has really strict laws. The exact wording is just to comply with a particular labeling law required by the state. And since it makes sense to give the same products to California that you give to the rest of the US, it's common for many products to have the warning printed on the label. Realistically, these products pose incredibly small health risks to the point where you shouldn't worry about them. You don't need to wash your hands after using them, though washing your hands frequently is better for your health as a rule of thumb."
] |
What is the history of the Vatican Vault?
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[
"I've actually spoken with a Benedictine monk who has visited the Vatican library (Father Mark Gruber, an anthropologist from Saint Vincent who studied and published a book on the Copts). In his words, it's just a library, and like any library or museum they lock away antiques and valuables in vaults so that they can be protected and preserved. Or maybe there's a giant queen spider in it... but until the Vatican opens it up to the public I'm going with Fr. Gruber's assertion."
] |
[
"No. Look at the other stories on that site- Chupacabra attack? They've been doing archaeology down there for years (though I don't know of any Hopkins sponsored work) but no Virginia Dare. Edited to add- From yesterday: _URL_1_ And earlier: _URL_0_"
] |
If there is such a dire global shortage of helium, why do we still use it to fill up balloons?
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[
"The \"helium shortage\" is actually a reaction to massive helium stockpiling of the US starting with the Helium Act of 1925 for use in airships and later on as a coolant during the Cold War and the Space Race. The idea was that it may be a critical natural resource similar to oil, but the progression of technology determined that it wasn't really that important and it was decided that the billion cubic meters of the gas we had collected should be sold off. This dramatically dropped the price of helium for decades, as the US government was selling a seemingly unlimited supply off at bargain prices. The \"shortage\" is that the US is coming to the end of their fire sale of helium which means the price will begin to rise to the actual cost of production, which means applications designed around the historically low cost of helium now are looking at a big price bump."
] |
[
"First of all, the *Hindenburg* was not a blimp, but a dirigible, a rigid airship. Second, when airships were invented, heavier-than-air flight was in its infancy, and it certainly wasn't capable of carrying people across oceans. You can't compare airship travel to any kind of airplane travel, as such a thing really didn't exist then. Airships competed against ocean liners. 'Ships like the *Hindenburg* were luxury hotels in the air, more or less. Best of everything for the passengers, no expenses spared, and all that."
] |
how and why does squinting my eyes damages them?
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[
"It doesn't. It can tire your eyes, but it isn't going to cause damage."
] |
[
"I asked my science teacher this like 10+years ago, basically your facial muscles squeeze your tear ducts"
] |
the Fibonacci sequence and why it is so cool.
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[
"My favorite Youtube math nerd, Vihart, has a [video](_URL_0_) on just that"
] |
[
"_URL_0_ Algebra and calculus are good, it really depends on what you need it for or what you've realised it is practical for. Any more info?"
] |
What is Condensation and why does it stick to windows?
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"Water can exist in three forms: ice, water, and steam. When it's cold, water is ice. When it's nice out, it's water. When it's hot, it becomes steam. The hot steam from a shower touches the cold glass of the bathroom mirror and becomes water again."
] |
[
"The sugar in the honey is drawing the moisture out of the bread. Honey is a _URL_0_ which is a hygroscopic substance. _URL_1_ \"Hygroscopic substances include cellulose fibers (such as cotton and paper), sugar, caramel, honey, glycerol, ethanol, methanol, diesel fuel, sulfuric acid, methamphetamine, many fertilizer chemicals, many salts (including table salt), and a wide variety of other substances.\""
] |
Why are diesel school bus exhausts allowed to exit under bumper when every other commercial vehicle has it routed above the cab.
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[
"Not all commercial vehicles have them over the cab. But trucks do, so the exhaust can clear the trailer. School buses aren't towing anything."
] |
[
"OK, well, let's try it! We'll make a Ferrari-looking car for the common man, instead of the boxier shapes we currently have! Wait, hang on, we'll need to raise the body a bit from the wheels. This isn't going to be used in racing conditions, it could be used on any road, even gravel. Don't want to have rocks constantly scraping the paintjob. We'll need to raise that roof a bit, too. We want tall people to be able to use our cars! Lengthen it. We need more room in the trunk. People are going to be carrying their stuff in these, if there's not enough room then they'll complain. Maybe make a hatchback version? We need more room in the back, too! And make it wider! We need to be able to fit three kids in there! Or even three squashed adults. Oh. We seem to be back where we started."
] |
Why doesn't the United States print currency that will not enter circulation and use it to pay off foreign debt?
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[
"I don't understand what you're implying. If you print money and pay it to someone (even a foreign someone) then you are putting that money into circulation. If you print money and keep it in a vault then it basically doesn't exist and you just wasted alot of paper for no reason. Money is either in circulation or it doesn't exist. Foreign holdings of dollar currency doesn't exclude it from the global dollar economy."
] |
[
"While something similar has been done, we just don't have the technology to create blood in the volumes we need. There is such a miniscule risk of infection via blood transfusion that I imagine the priority on such research is low. There are many levels of quality assurance that goes into making our blood supply safe, and it is only getting better as time goes on."
] |
Even if we were to figure out light speed travel how can it possibly be safe?
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[
"> Like I'm sure it's impossible to get from point A to point B in space in a \"straight\" line without coming across an inevitable planet, asteroid, star, black hole or whatever else. Not at all. If you pick a random direction in the sky, you are *overwhelmingly* likely to go many billions of light-years without hitting a damn thing. Space is REALLY empty."
] |
[
"You would be the first person from earth to visit another planet. You would have your name in the history books along with every other great explorer we currently celebrate. It's a chance to do something that litterally no other human has ever done. As for ethics, well what's unethical about it. Everyone who signs up for the program is/should be well aware of the risks, possible outcomes and likely hood of success/failure. So long as those things are met there is nothing unethical about it. People are signing up of their own free will."
] |
Why do a majority of women have long hair, and men have short hair?
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[
"It used to be that men would cut their hair so it would not be a hindrance in battle, or while working jobs like blacksmithing (i.e., getting in their eyes, or getting pulled by their enemies). It became a cultural norm."
] |
[
"It minimizes the ability of your curves to cast shadows on other parts of the body, and falls off more easily into the lighting behind you. By providing fewer references, our eyes lose visual cues as to how \"wide\" the subject is. Edit: In addition, it creates an optical 'void' that appears to pull the edges in around it as your brain tries to fill it in with something that it knows; it's a standard optical illusion."
] |
Why do parents keep pressuring their children to go to college and take out school loans when there are all of these statistics about then national loan debt.
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[
"There is a larger wage gap between college and high school graduates than ever before. Among Millennials it's about $17,000. I'll bet it will only increase. You can pay off your investment in a state school in four years of average higher salary. Additionally, unemployment among college grads is half that of those who have a high school degree. Sources: _URL_0_ _URL_1_"
] |
[
"Sugar tastes good. When faced with a choice between that which is smart and that which is pleasing, most people will spend their money on the latter. A business exists to sell people what they *want* to buy, not what some might feel they *should* buy."
] |
Why is twoxchromosomes a default sub while there is no default male counterpart?
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[
"Guys can find a welcome audience to talk about guy things in nearly any sub, so there's not really a need for a special \"guys only\" sub. This is like if someone opens a vegetarian restaurant and you ask \"but why isn't there a restaurant for people who eat meat?\" You already have tons of options for that! Go anywhere, they'll have meat on the menu. A restaurant that serves meat is by far the norm. You're not being cheated out of anything just because a tiny fraction of subreddits are oriented to women's interests."
] |
[
"Reddit is hosted on AWS, which is many massive server farms. One of the advantages of providers like AWS is that when high traffic hits, you can have your system automatically spin up additional servers to handle the load, and then to shut them back down once the demand goes down."
] |
How can websites like aliexpress offer their products so cheap with free shipping all over the world?
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[
"Chinese government actually subsidy cost of shipping to support exporters, so that's why they can send you item you bought for 0.1$ with free shipping. Longer explanation would be that they ship in bulk with pay per volume and not per item, so they don't care it's actually one small item for one customer, but anyway it's subsidised by Chinese government."
] |
[
"Because they displace that weight with the sheer size of the hollowed out size of the ship. The volume of water moved by the hull matches the weight of the hull. Archimedes principle - _URL_0_"
] |
please... Martian movie question (spoiler alert)
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[
"The thing that made the potatoes so special in the first place was that they were still fertile normal potatoes. If you read the book it talks about it a little more. All the other food was freeze dried so the bacteria died. The potatoes he started with had bacteria necessary to keep them growing. When the air lock exploded all the bacteria died instantly from the atmosphere of Mars. TLDR-- It's kind of like if you boil a pumpkin seed and try to grow it again. Even though the soil has the nutrients it's still a bad seed."
] |
[
"They use [reaction wheels](_URL_0_) in most cases, which run continuously and only need some electrical power to run. The main drawback is that they wear over time and eventually fail, so engineers often put spares if missions are expected to last for long time."
] |
How would researchers determine whether a species was warm or cold blooded based solely on fossilized evidence?
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[
"In regards to dinosaurs, it is because the rate of growth in some dinosaurs (calculated by growth rings in bones) is more in line with mammals than that of modern day reptiles. With this we can assume that they had to be warm blooded to maintain this rate of growth. Additionally, I believe the dinosaurs that we believe were warm blooded are the theropods, the dinosaurs that gave rise to Ava (aka as birds). Since birds are warm blooded, we can conclude that their ancestors must have been as well."
] |
[
"I'm in the car right now (not driving), so hopefully someone can better elaborate. Rosalind Franklin took X-ray photographs (crystallography?) of the DNA double helix. She was working with James Watson and Francis Crick who published the information and received the Nobel Prize for the work. Franklin was not awarded because she was dead at the time of the awards and NPs are not awarded post-humously. But here is a link to learn more. _URL_0_ I have no idea how x-ray crysallography works, so it would be cool if someone can elaborate."
] |
How full are full moons?
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[
"> Does a full moon actually mean we can see 50% of its surface? Also, does the relative \"fullness\" change from month to month? Very close to 50%-- actually about 49% or so. The Moon's orbit is elliptical, so depending how close it is to the Earth, we can see a tiny bit more or less of it. In addition, that elliptical orbit means that over the course of a month, we get to see almost 60% of it. [This gif](_URL_0_) shows the Moon over the course of a month. As you can see, it appears to wobble, a result of its elliptical orbit which presents slightly different parts to us."
] |
[
"We aren't really sure why, but it doesn't seem that something like that can be done. Think about it like your bladder; you can build up a need to urinate, but you cannot urinate so much that your bladder is more than empty."
] |
Why do women play softball instead of baseball?
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[
"Softball actually started off as a man's sport. Its a variation of baseball that was meant to played inside during the winter. They have become two separate sports played by both men and women. Baseball became more popular with men. And softball became more popular with women. Just wanted to clear up a misconception. I dont know why softball stopped being as popular with men."
] |
[
"Its the easiest way to get out of the kitchen for a 5 minute break."
] |
How does turning a shower knob more or less regulate the temperature of the water?
|
[
"Depends on the shower type. If it is one that heats cold water. Then it varies the amount of heating applied to the water. If it mixes hot and cold water together then it varies the ratio of hot to cold."
] |
[
"I believe what you're referring to is an infrared thermometer. You know how a camera gathers light from your environment to take a picture? An infrared thermometer works on the same principle. The thermometer is simply reading the infrared radiation being emitted from whatever you are pointing at. (Except the thermometer only has a tiny pinhole, so you only capture a specific area. You will notice that these thermometers generally are rated by how tight of an area they can measure at certain distances.) The red \"laser\" is just to help aim."
] |
Would we be able to save energy if Google made their homepage black instead of white?
|
[
"LCDs work by applying a voltage to each pixel which \"opens\" them and allows light to pass through. No voltage and they are \"closed\" thus blocking the light. Thus a black screen takes less electricity to run than a white screen but the voltages applied are very low. Most of the power will be drawn by the backlights which are always on when in operation. You can see [here](_URL_0_) that power draw reduces on average by 3.16% for a black screen versus a white screen. Some monitors moreso, some less but in most cases not a whole lot."
] |
[
"Engineers are working on that. But you also have to realize this may be a bit misleading of a thought. Battery consumption via screen lighting is also a majority of what a phone does nowadays. Think that no matter what app you are using or what you are doing on your phone you'll always have your screen on. It is very similar to the idea that a majority of car accidents occur within 5 miles of your house. Well obviously. Because the highest majority of miles are driven within 5 miles of your house. Doesn't mean that each of those miles is necessarily more dangerous than any other mile. Just because a screen takes up a majority of the battery doesn't make it the most wasteful part of battery life."
] |
How is it that certain objects absorb some colors and reflect others?
|
[
"I can go into more depth if you want, but atoms have resonant frequencies which prefer to absorb certain frequencies (colors) of light, and reflect other colors."
] |
[
"A wet cloth looks darker because less light is reflected from a wet cloth. _URL_0_ Google is useful"
] |
could you orbit a planet with much higher gravity at an altitude to give you earth like gravity?
|
[
"When something is in orbit, that means that it is in freefall, and thus the experience of living inside the space station would be that of weightlessness. It's true that the gravitational force drops as 1/(distance to planetary center)^(2), so at a suitable altitude, yes, the gravitational force would be comparable to the surface gravity of the Earth. However, you'd have to be at that altitude and not be in free fall (say at the top of a really tall mountain or building -- leaving engineering considerations aside). In such a situation, if the planet is rotating, you'd have to pay attention to rotational effects (\"centrifugal force\") as well to figure out the correct altitude."
] |
[
"I mean, you can work out and gain mass, but the statement about muscle is taking into account that you follow the same routine as in earth and were stabilized on not gainong/losing muscle. What it means is that since you don't make work against gravity to walk, move things, etc. Doing the same workout with the same diet you would lose muscle, as you are doing less force and consequently your muscles are doing less work so they aren't as needed, so they reduce mass."
] |
Which is less hygenic, rinsing your hands with plain water, or walking straight out, after using the toilet?
|
[
"Handwashing (with soap or not) removes bacteria from your hands via mechanical action, it does not kill the bacteria. Soaps with microbicides (triclosan) are no more effective than other soaps in reducing microbial numbers. In theory the surfactants in soaps ought to disrupt the microbial ability to adhere to your skin and in turn be more hygenic. As I understand it evidence for this is somewhat mixed. Using soap is strongly confounded by the fact that poor handwashing technique greatly reduces the effectiveness of handwashing (with or without soap). Here's a couple of papers showing mixed evidence for handwashing efficacy: For soap: _URL_1_ Against soap: _URL_0_ For technique as the deciding factor: _URL_2_ In short you always need thorough handwashing technique, splashing some water on your hands and drying them on your trousers doesn't count. Soap probably does help but evidence is mixed."
] |
[
"It's not going to be spoiled in the true sense. Spoiled is when food has bacteria/microbes growing in it that have started to change the food in some way, as a byproduct of starting to digest the food item. Almost all surfaces are covered in microbes, and certainly anything in a regular home is. Whether there are pathogens present is a different issue. But stickiness of the food isn't really at play, as what is sticky to us is not necessarily relevant to microbes. In fact, if a microbe \"wants\" to stick to a food, and has the structures to do so, it will. But really, by the time it's hit the floor, it's already covered on the dropped side by microbes. So you have to evaluate, do I trust that the surface I dropped it on has few or no pathogens? Personally, at home, I'm fine with it. In lab, in the street, pretty much anywhere outside of my home, I don't make that assumption. And nothing you do to try to remove those microbes is really going to do much, short of (re)cooking the item."
] |
Why is it essential that the US is included in the Iran deal?
|
[
"Because the US is the world's largest economy and it penalizes all companies that deal with Iran in any way, directly or indirectly, so no one wants that hanging over their head. It's an economic war with Israel and KSA/Sunni muslims trying to destroy Iran's economy and asking for the US to back their side"
] |
[
"If your next door neighbor is trampling flowers in your backyard, and your much larger, much bigger neighbor from across the street decides to try and stop him, it's in your interest to just let him do that, whether with implicit or explicit approval. ... especially when you can't get to that corner of the backyard yourself, because you're still dealing with your stove being on fire and the vacuum going out of control."
] |
why is it that i can go to sleep at 12 feeling not tired and then wake up at 8 feeling tired?
|
[
"Because you sleep for the exact wrong amount of time and end up with something called sleep inertia. Try waking up at 7:30 instead."
] |
[
"Your eyes are perceiving that your body should be in one position (lying down in case of the linked gif), yet the signal from the balance centers in your ears are sending a different signal to your brain. This dissonance causes your brain to try and make you feel how you should based on the signal from your eyes."
] |
does a television set displaying an all black screen absorb more light from other sources than a television screen displaying an all white screen?
|
[
"No. How much light the screen is producing doesn't really alter its reflectance as far as I am aware. It will likely impact how much you will subjectively notice though, as the light coming from the screen will overpower reflected light from elsewhere."
] |
[
"There is a protein in all of out skin called Melanin. It is formed in our skin in the shape of little granules. They attatch to skin cells and rise to the surface of our skin and fall off. The more melanin attatched to your skin cells, the darker you are. Everyone has the same amount of Melanin producers, but everyone produces Melanin granules at different rates, which is a genetic property, and is also affected by Vitamin D. Melanin's purpose is to reflect UV rays, which cause mutations in our cell's DNA and cause caner. People with more sun exposure are darker to reflect more UV rays, and people with low sun exposure have less, so they are paler so they can absorb more sunlight and get the proper ammount of Vitamin D."
] |
Why do humans have different eye colors? Were they ever an evolutionary advantage?
|
[
"A bit off-topic: You should take a step away from the idea that evolution only 'creates' something because it would be advantageous to the species. Evolution is much more chaotic than you may think. Things just happen more or less by accident (mutation), and if these mutated species somehow survive (even if this new mutated trait doesn't serve any purpose - but also doesn't hinder them) they just keep it and it shows up every once in a while."
] |
[
"Specializing helps with optimization. Cows can't eat meat, but their teeth and multiple stomachs are ideal for eating grass. Humans have to have sharp teeth for meat and grinding teeth for plants and our digestive system is inefficient at processing plant matter. Versatility is obviously useful, but there are trade-offs. A spork isn't as good as a fork in stabbing or as good as a spoon at scooping."
] |
Why doesn't the air pass through all parts of our body?
|
[
"Molecules in the air can and do enter our body from outside the lungs through a process called [diffusion](_URL_0_). [However the surface area of our body](_URL_1_) compared to the surface area of our lungs is tiny, so it has a negligible effect."
] |
[
"In short, the time the lightening is touching the person is too short to fry them completely. It is also focused on one relatively small area on the body, so any collateral damage would be minimal."
] |
Why do so many people say quantum mechanics is non-deterministic?
|
[
"Wikipedia isn't an authority in this case. The problem I always have with it is that they often don't do a clear job of differentiating the consensus view above others. And the consensus view, as I see it at least, is that quantum mechanics is at least non-deterministic in so far as it is incalculably so. And that's all the science can really say, if we can't calculate a prediction for the outcome of an experiment, then it's as good as non-deterministic as you can get. If there's some underlying determinism that we can't measure or calculate or whatever... who cares, that's a problem for philosophy not physics; not that people who are physicists/scientists can't engage in both, but they're not acting *as* scientists when they provide philosophical interpretations of quantum mechanics."
] |
[
"The Quantiferon test is a brand name for a form of interferon gamma release assay. Simply put if your immune system recognizes tuberculosis then it will release a substance when exposed to the antigen for that substance, a chemical marker specific to that infection. The first two zero results are for exposure to different kinds of TB and show your body doesn't react to them. The third is a test to see if your body is reacting to anything (which it is) as if it isn't then the test is inconclusive and you have immune problems. The \"nil\" is a measure of if there are any other antigens already in the blood from an ongoing illness that could cause those immune cells to release substances like the test measures, skewing the results. It is quite low so the results should be accurate."
] |
Why aren't trains more automated or fully automated? ie: driverless
|
[
"Safeguards to protect against the type of thing that happened in Spain do exist. [Automatic Train Control](_URL_0_) systems are intended to slow the train down if it exceeds the safe speed. Here in Sweden for instance, the vast majority of the national rail network has such a system. It should be mentioned that many obstacles for introducing automated transport systems (be they trains, cars or something else) are of a social and legal nature, and not engineering problems."
] |
[
"It's an incredibly expensive and long process to build desalinization plants, and the plants require a lot of ongoing maintenance (all that removed salt has to be cleaned from the filter and dealt with), so it ends up being really expensive way to produce clean water."
] |
Why do babies laugh at something multiple times?
|
[
"Because he is experiencing that particular experience for the first time in his life, and it is tripping him the hell out."
] |
[
"The general consensus is [attention and approval seeking](_URL_4_) or [medical issues](_URL_1_). In [domesticated animals](_URL_2_), the approval seeking is generally from the owner. Because we see this in wild animals as well, it can't just be a human-approval mechanism. The attention seeking can be extended to the animal's peers / pack / parents. Medical issues that cause this can range from [neurological](_URL_3_) all the way down to [fleas](_URL_0_). It's a surprisingly well studied issue, with [hundreds of papers](_URL_5_) written on various causes. Edit 1: I categorize the first video as neurological because there are compulsive aspects to what the wolf is doing. It is possible that there's underlying injury, but we'd need a history to know for sure. The second video has the foxes scratching for a good portion of it, an indication of fleas, mites, ants, etc, and a possible reason they would attempt to catch and groom the tail."
] |
Why do people get sleepy and / or eat when they get bored?
|
[
"Think of it as evolutionary to survival. If you aren't doing anything, those are the things you should catch up on so if you do have to fight for your life, your ready to go."
] |
[
"Think of it this way: you have a limited amount of focus points. When you take the effort to do productive work, you spend those points. When you are taking time to do unproductive things(surfing internet, taking a break, etc.), it's just a way for you de-stress and replenish your supply of focus points. If you're spending your focus points by focusing on other productive things besides work, it looks like you are spending effort that could be used for your job."
] |
Does a heat engine always require a heat differential? Or are there engines that work on ambient heat energy?
|
[
"You only get a net flow of heat from areas of high temperature to low, so a heat engine could only work off ambient heat if the ambient temperature was different from that of the engine (or can be manipulated into being different, the most commonly used way being to change the pressure of a gas)."
] |
[
"> Is this true This is true. In statistical thermodynamics, two particles that are distinguishable have a different number of permutations of possible states than two indistinguishable ones. (e.g. if you have two holes in a pegboard, you can place a blue and a red peg in them in two different ways, but with two indistinguishable blue pegs there's only one way) That means there's a difference in the number of unique states, and thus a difference in entropy. In other words, you can measure the fact that they're indistinguishable."
] |
How did the first person create the first computer language?
|
[
"The first computers were programmed manually, directly in binary by flipping switches. Later efforts were taken to more easily enter binary such as punch cards which could be automatically read, and then later symbols were invented to represent binary values. From then it shifted more towards symbolic programming languages."
] |
[
"From _URL_1_ : ''2.9 Argument from Extra-Sensory Perception The strangest part of Turing's paper is the few paragraphs on ESP. Perhaps it is intended to be tongue-in-cheek, though, if it is, this fact is poorly signposted by Turing. Perhaps, instead, Turing was influenced by the apparently scientifically respectable results of J. B. Rhine.'' J.B. Rhine was also one of the top guesses when this was asked previously here _URL_0_"
] |
How will modern burial techniques impact the preservation / fossilization of human remains?
|
[
"For the most part, our burials involve embalming and burying in a concrete vault underground. It appears that this creates ideal conditions for what is called a wax mummy. It's where the fat in the body turns to wax. A google search pretty easily pulls up pictures of wax mummies, they are rather eerie."
] |
[
"Let's say you have a 7 lane interstate. At each end there is a toll booth. In the past payments were processed manually and there was a receipt that had to print, but the printers were slow. Only do much traffic could get through. Fast forward to the future where you pay with the touch of a button and get an instant receipt or pre-pay before you get there and just zoom right through. Ignoring I know nothing about toll booths, this is basically why. The info in the past couldn't be processed as quickly, so there is always a bottleneck. Today it's much faster. I'm not sure if we've reached the physical limitations of the current infrastructure though. I know we've come up with better ways of transporting the info such as the digital equivalent of carpooling or taking the bus. Only so far you can go before you'll have to expand the interstate or change to a better mode of transport. Like bullet trains...or Elon Musk's idea of the hyper train system. What is it called again?"
] |
Are modern humans stronger or more athletic than our pre-agricultural counterparts?
|
[
"There is an argument using evolutionary theory that agriculture was only adopted to increase group fitness at the cost of indivual fitness. Lots of civilisation diseases started with the adoption of agriculture. So there is the argument that agriculture made civilisation possible but at the cost of pure indivual strength and physical prowess. There is lots of evidence that early agricultural societies had less than healthy members compared to hunter gatherers. When you think about it, the indivual skills of a warrior in a large army is less important than pure numbers, most armies in the past were farmers called to war once a year, and yet the prevailed most of the time against nomad societies whos way of life made them formidable indivual warriors like the steppe people, just by numbers alone. Edit: If someone is interested where these theories come from, I recommend these books: _URL_0_ _URL_3_ _URL_1_ _URL_2_"
] |
[
"You may consider asking this question in /r/askscience or possibly /r/AskAnthropology if you don't get an answer here. It seems like your question and potential answers may be cross-disciplinary."
] |
Can you help me find more films/series depicting the 18th/Early 19th centuries in Europe and the Americas?
|
[
"Hi! A message from the mods: suggestions are clearly welcome, but must be accompanied with a fairly good explanation as for *why you are recommending the media*. It might also be good to speak of what you thought was particularly good, and what potential problems it might have. Cheers."
] |
[
"I will only answer part because I only know about that part. The HDTV Grand Alliance! The HDTV Grand Alliance was formed in the early 1990s by MIT and a bunch of TV manufacturers. They wanted to agree on how to make TV fidelity better and come up with a uniform standard that could be imposed upon media producers. The nerds at MIT calculated that 16:9 was the best ratio because it made for the smallest average black boxes when switching between 4:3 (old movies and SD television), 1.85:1 (1950s-80s low budget movies), 2.35:1 (\"scope\" feature films), and the other (British, Japanese) display ratios that deviated from the 4:3 standard. The film industry was very unhappy with this, as they had been pushing for letterbox television (2.35:1) so that they could make VHS/DVDs without black boxes or panning. But all of the TV manufacturers liked the arrangement and also made all the TV cameras so they had considerable control."
] |
Is there an upper limit to how large life on Mars could have been? People often entertain the idea that there once may have been bacteria on Mars, but how do we know there weren't e.g. Trees, or other larger life forms there?
|
[
"We don't know for sure... but assuming Earth is average, we can look at how long it took for multi-cellular life to arise here and assume that's how long it takes, then apply that to how long we believe Mars might have been conventionally habitable. I haven't looked up the numbers recently, but I'm fairly confident there simply wasn't time for multicellular life to evolve on Mars unless it got very, very lucky or life on Earth has been exceptionally unlucky. *edit:* It took about 3.75 billion years for life to evolve to multicellular forms on Earth. _URL_1_ It's thought Mars may have been habitable for perhaps 2 billion years. _URL_0_"
] |
[
"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. The 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. Even 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. Additionally, 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."
] |
What makes a person "insane" as opposed to "sane"?
|
[
"Our concept of mental illness is defined by the [DSM-5](_URL_3_), a big book of failure modes for the human brain and psyche. We're complicated beings so there are a lot of ways it can go wrong. \"Wrong\" in the last sentence is defined as: 1. Loss of contact with reality, although some people would debate that. 2. Inability to function in society."
] |
[
"The retina of your eyes have different colored cones that can detect red, green, and blue light. Your brain translates the relative activation of these 3 wavelengths into the colors we perceive. This illusion occurs because when we stare into the color-inverted image for long enough, the color-sensitive cones in our eyes adapt to the overstimulation and lose sensitivity. For example, the part of our retina looking at the red shirt will eventually get tired of displaying red (because that color is activating more than green or blue), so when we look at the blank wall, the green and blue receptors are more sensitive (less tired), and for a moment we perceive them to be stronger than the red. We now see her shirt as green because it is the inverse color of red. If you want to learn more about color opposites read up on complementary colors, the visual aids from another source would explain more than I could with only words."
] |
If black holes have a singularity at the middle, how can there be different "size" black holes?
|
[
"The curvature of spacetime induced by the central singularity is proportional to the mass of the object. Usually the size of a black hole refers to the radius of its event horizon, which for a non-spinning spherically symmetric object is given by the Schwarzschild radius (Rs): Rs = 2MG/c^(2) where M is the mass, G Newton's gravitational constant, and c the speed of light. So, a black hole with a larger mass will also have a larger event horizon. By the way, a singularity is thought to form only if there are no other forces to prevent the collapse of the material to a point. However that does not imply that such forces will not exist for very dense objects."
] |
[
"Yes, it can occur that through gravitational lensing (as it is called), we an see more than one image of the same object. For this to occur, the Earth, the object being imaged, and a very large gravitational mass must all be close to collinear, so that light passing from the object above, below, and to the sides of the large gravitational mass can be deflected toward the Earth. (Remember, the deflection of light by gravity is generally a really small effect.) Depending on the particular relative configuration of the object, the large gravitational mass (a quasar, a galaxy cluster, whatever), and the Earth, you can get what are called [Einstein rings](_URL_1_), [Einstein crosses](_URL_2_), or other multiple image arrangements. You can read more and see some pictures [here](_URL_3_) from NASA. You can read some of the history of this [here](_URL_0_)."
] |
How a plane with both engines which are completely destroyed can still fly and change direction on the sky?
|
[
"Contrary to what Hollywood would show you, planes don't just fall out of the sky when their engines stop working. Instead, they turn into gliders, which can travel for long distances as long as they're okay with slowly descending towards the ground. If the plane was high up in the air, and traveling at cruising speed, it can fall gracefully for many many miles before it reaches the ground. Steering an aircraft is all about the air flowing over the flaps on the wings and tail of the aircraft. When the pilot steers, those flaps change their angle to move the aircraft, no engines needed."
] |
[
"Blood doesn't rush around your body in one big tube. What happens is the blood vessels split and become thinner and thinner. Think of a fan where the bottom is the main artery which splits into finer tubes called capillaries. This splitting happens all through your skin, so there are millions of very fine capillaries covering your body. Once the cells have taken the oxygen from the blood through the walls of the capillaries and given up the waste products back into the blood, then the capillaries then all join back up again into veins and travels back to the heart. So, when you chop off an arm some of the fine capillaries are lost but the vast majority are still there. The amount of blood and the pressure of the blood get messed up for a while, but the circuit still exists."
] |
During the First World War did the German soldiers also walk into waves of machine gun fire?
|
[
"* [Did people REALLY march into machine gun fire in 1914?] (_URL_1_) * [Were the Generals in 1914 grossly incompetent?] (_URL_2_) * [Did the French fight in line formation in August, 1914?] (_URL_0_) ^ These answers I've given above should be pertinent! Suffice to say that NO ONE walked into waves of machine gun fire in 1914, or it would seem at any point of the war. Poorly trained soldiers would naturally bunch together, and poor reconnaissance would lead a unit in marching order to be fired upon by the enemy (Both befell the French in August 1914). Moreover, having read the accounts of soldiers (particularly German soldiers) from the Somme, 3rd Ypres and other campaigns, most tend not to be very descriptive in their depictions of enemy tactics, with the enemy coming on in 'hordes' and 'waves.' The Germans certainly launched their fair share of futile infantry attacks, in particular at 1st Ypres, the Somme and Spring Offensives of 1918, but they did **not** walk into machine gun fire."
] |
[
"I cannot comment on the Annals, but in the Song of Roland, it's clear from the text that the author has very little real knowledge of those the author calls Muslims. He makes all sorts of descriptive mistakes that a person with even passing familiarity would not make (For example, Muslims are extremely monotheistic, yet the author does not seem to recognize this.) In fact, the poem's main story is about a battle (IRL - The Battle of Roncesvalles) between Charlemagne and Spanish Muslims. Among the many poetic embellishments the author makes is to turn the Christian Basque peoples Charlemagne actually fought into Muslims. I suspect the answer to your question would be \"no\" there is no precise distinction made by the author(s) of the Annals, and even if there were, it's unlikely we'd be able to determine what it is, given the confusing nature of their knowledge (e.g. what if the distinction is based on a perceived difference that we do not recognize or understand?)."
] |
What's the difference between bumblebees and honey bees?
|
[
"They are evolutionary cousins, both part of the sub-family Apinae. They are both social insects, but honey bee colonies are much larger than bumblebee colonies. Bumblebees are stouter than honey bees, and they look furrier. Also, honeybees build honeycombs, whereas bumblebees live in the ground."
] |
[
"> how it really amounts to a bunch of bologna I don't have an answer, but I do need to point out that bologna = lunch meat. Baloney = nonsense."
] |
Why do helium balloons on a string deflate, but helium balloons on a stick never deflate?
|
[
"Helium balloons on a string are normally latex balloons. The ones on the stick are usually made of Mylar. There is a different amount of insulation between the two materials and the outside of the balloon causing one to float longer than the other. From what I understand anyway."
] |
[
"Put a slinky in a long glass tube and fix one end of the slinky to one end of the tube. Now lay the tube on your desk. The slinky is all curled up . Next, stand the tube upright. One end of the slinky is fixed to the top of the tube and the bottom of the slinky dangles down. What if you held the tube at an angle... say 10 degrees off of exactly horizontal. Gravity still pulls down on the free end of the slinky, but a lot of the weight of the slinky is supported by the tube. The slinky is all bunched up, but not completely bunched up (like in an exactly horizontal tube). The longer the slinky is the more vertical the tube is. Put another way, you know how much the tube is tilted based on how long the slinky is. Phones do something similar. They have a tiny 'springs' that are effected by gravity. The phone can measure how deformed the springs are which means it knows how vertical/horizontal the phone is."
] |
How do songs in video games loop perfectly?
|
[
"There's two parts to it: 1. The song's composer writes the music so that it has a long section that doesn't really \"build\" toward anything musically. This can be the whole song or just a part in the middle of a song that does have a definite beginning and end. This brings us to the second part. 2. The composer tells the game where the beginning and end of the song are, and where to loop back to in the middle part. In the days of MIDI music this was done using tags in the actual song files themselves. The game uses this information to know exactly when to loop and how far back to jump. The beginning and end parts of the song might only play when the player enters and leaves the area where the song is used, or at some other point decided by the game's level and story programmers."
] |
[
"Marketing and tracking. I bought \"TRON: Evolution\" when it first came out, thinking it was a single player with the option of networking. Nope. You have to either have or create a Microsoft \"LIVE\" account and log on to that in order to play a game that is locally installed. They track everything, and sell it to third-parties. Oh, but they'll never admit that. According to the game, it's so that my progress can be saved. (Why can't I do that LOCALLY?)"
] |
Why in school do we not learn about anything before the 1400s (mainly Reformation and Colonization) if it is considered the "Common Era"? What happened?
|
[
"Three really big changes happened during the 15th century. The widespread adoption of gunpowder, printing, and the compass in Europe. They were all invented much earlier, but it was only during this century that they became powerful forces of social change. Almost the whole face of the modern world can be seen by carefully following the implications of those 3 inventions."
] |
[
"Congratulations to our winner of this month's book giveaway, Andrew Stead! The selection of books we have available this month are: *A Savage War of Peace: Algeria 1954-1962* by Alistair Horne, recommended by /u/Bernardito. *1177 B.C.: The Year Civilization Collapsed* by Eric Cline, recommended by /u/kookingpot. *Becoming Mexican American: Ethnicity, Culture, and Identity in Chicano Los Angeles, 1900-1945* by George J. Sanchez, recommended by /u/cordis_melum. And my suggestion, *Angkor and the Khmer Civilization* by Michael D. Coe. Andrew, I'll be sending you an email via Patreon to figure out which one of these you'd like and how best to get it to you."
] |
Can water act nonpolar? And dissolve fatty acids?
|
[
"Water is a polar molecule so it interacts greatly with other polar molecules. Due to entropy you can always dissolve a little bit of non-polar material. Generally water does not dissolve non-polar material. Fatty acids contain a small polar group (carboxylic acid group) and a very long chain of non-polar carbon. If the acid group has a negative charge (has lost a proton) the fatty acid becomes a lot more soluble but is still not very soluble. Another factor is if the fatty acid is saturated or not. An unsaturated fatty acid (containing double bonds) makes the carbon chain twist and turn increases the solubility since the fatty acid in itself is less able to \"pack\" together and interact with itself. TLDR: Fatty acids with short carbon chains (around 5-7 carbons) are soluble in water. Fatty acids with longer carbon chains are pretty much insoluble."
] |
[
"The main problem is that detergent is largely ineffective at removing it from surfaces like dishes, most notably industrial dishwashers. Hand washing is effective, but alcohol hand sanitizers are not. No lipid envelope just means usual methods of removing it don't work well."
] |
- The Second Amendment
|
[
"The idea behind this amendment was that the people would be able to keep sufficient firepower to use to ensure that the federal government would not be able to oppress them. This was a major worry of the founding fathers and a safeguard against their new system of government (America), turning out as a tyranny, as England was seen as at the time. Not everybody can own a gun, and the amendment has also been interpreted to just mean that the States can have militias/National Guards (only the Federal government can have an army)."
] |
[
"I would personally give my left arm to be ambidextrous."
] |
Why are there still college football games where top teams play unknown colleges?
|
[
"It's a 'win-win' scenario for both schools. The 'powerhouse' team, like for instance Alabama or Clemson, get an easy win because they're able to use their legacy to recruit better players. The 'unknown' college gets 'free' publicity for playing a well-known school, and if they happen to pull off an upset, then it's a great day for the 'unknown' college."
] |
[
"Discovery Channel, TLC, The History Channel, they started out as niche channels...inexpensive programming aimed at a specific audience it was easier to target ads for. Then came *Mythbusters*, a big hit that appealed to a broader audience. Soon all the networks wanted to try to reach a wider range of viewers, and but instead of making clever shows within their niche, like *Mythbusters*, the just made dumbers shows that grew to have little to do with their niches. *American Chopper*, for example, started out as a interesting show about building things, but turned into a contrived soap opera. The concept of *Pawn Stars* is sound, there is a good deal of history in many of those items, but they went with character based buffoonery. And unfortunately, that's what is getting the ratings...for now. My hope is more cable networks, like USA and TNT, are going to get into the game, and outcompete the niche channels, sending them back to their original ways."
] |
Does a black hole grow as it absorbs more mass?
|
[
"There is a direct correlation between the radius of a black hole's event horizon, and the amount of mass that is contained in the black hole. This is known as the [Schwarzschild Radius](_URL_0_). As it obtains more and more mass, the radius of the event horizon will continue to grow."
] |
[
"For the text: Hm, I think you misunderstood what the space-time is. It's not really \"space and time\", it's the \"fabric\" on which the universe is set upon. So basically, for all we can tell, it works the same way here, and it works \"there\". And time, as you describe it, goes by here the same as it goes by \"there\" (with a tiny difference due to relativity, but it isn't really that relevante). For the title: Yes and no. No because for a long time we assumed the universe to be an emptiness that's slowly being filled with \"things\", and without any drag, it would keep on growing forever, but then they realized gravity kicks in, and gravity is the drag. Yes because when we realized that what's growing isn't the volume of \"universe\" filled with \"things\", it's really the space-time that's expanding, and making the universe itself bigger, something like, growing from inside. Hope it helped!"
] |
Why is air invisible? (from my 3 year old)
|
[
"It's made of tiny particles that are so far apart that light beams can go between them. Your shirt, on the other hand, is made of larger particles that are very close together, so light (and your hand) cannot pass through as easily."
] |
[
"It really depends on what you mean by \"see.\" If you mean see with the unaided eye, then no we cannot. If you mean unambiguously detect and visualize, then we can. _URL_0_"
] |
Why is the central carbon atom in Allene not hybridized?
|
[
"I believe the test may have been wrong. The two end carbons are both sp2 hybridised, and the middle carbon is sp hybridised. This sp hyrbridisation arises because the molecule is linear (due to the two double bonds) and undergoes the equivalent hybridisation of an alkyne. The 2s orbital on the middle carbon overlaps with only the 2px p orbital leaving the others to form the pi bonds."
] |
[
"you'll be looking for larger scale-structure than just galaxies, or even clusters--but some researchers are trying to tie the development of some very large scale structures (\"filaments\") to the anisotropies in the CMB. _URL_0_"
] |
What is the value of learning from history and why should it be taught?
|
[
"Before anyone else chimes in, I just want to parrot the thoughts of early medieval historian Guy Halsall, in stating that though history is helpful in learning how the world came to be the way it is, it is NOT for drawing lessons as to where we are going. It's no more a scry for the future than a magic 8 ball giving ambiguous answers that can be interpreted both ways. Much like where the stock market is going to go, narrative reasons are applied after the fact, once better information and hindsight is gathered, bearing in mind that this too is still a limitation. While the present is unfolding into the future, we can only grasp at the darkness of the incomplete. One could argue, we're doing that with our pasts as well."
] |
[
"Johnnie borrows $1000. He doesn't pay in time. You send the boys to rough him up a bit, get $400 out of him. He still owes you $600+interest. Ifnyou don't write that down, how are you going to remember how much he owes you? Johnnie is just one of 100 people that owe you money."
] |
Where do photons that are emitted from a light source ultimately end up? Do they vanish into thin air, or do they collect somewhere?
|
[
"Photons travel and travel. If they encounter something, they might get scattered (re-directed) or they might be absorbed. All the light you see from stars in the night sky has traveled across light-years of space until they hit your eye. Space is so empty that photons largely just travel."
] |
[
"It's not voodoo magic. It's kind of like brushing your hair. When you get up in the morning, your hair (assuming you have more hair on your head than I do) is all tangled from tossing and turning and all that other jazz. This is what regular light coming from, say, a light bulb looks like. It's all tangled and scattered. What do you do to fix your hair? You comb it, of course. You brush it again and again, until it's all straight and perfect and just the way you want it. The laser unit does the same thing to the laser light, only instead of a comb, it's got a set of mirrors that comb the light back and forth until it's just right--at which point the light is allowed to shoot out from the tip of the laser and entertain you while you use it to drive the cat crazy."
] |
Why do beards appear to grow in the wrong place on overweight people?
|
[
"I don't think the term 'neckbeard' specifically applies to overweight people. If you can grow a full beard (AKA are fully mature) then you will grow hair on your neck. I think what happens, however, is that overweight or other unattractive people, who know they are unattractive, simply don't see the need to properly groom, resulting in them not shaping their beards at all, whereas someone who takes pride in their appearance is more likely to trim their facial/neck hair properly. I also think that perhaps overweight people sometimes neglect trimming their beards because it hides their double chin. This is dubious, because we all know it's there."
] |
[
"Nothing \"tells it to\" the changes dont happen during a creatures life, the changes come from mutations in the genes of offspring and nature decides which ones live and which ones die. When a mutation happens its usually bad but rarely a mutation can be beneficial. Take polar bears. Some time a long time ago a bear was born white. Usually looking different is a bad thing but this bear thanks to his camoflage became a very successful arctic hunter. He was well fed and strong and had lots of food to spare for all the lady bears. This means he got to reproduce a lot and his mutation for being white passes to some of his offspring. Soon enough there are lots of white bears, they are better suited to hunting up north. Their brown brothers either die off or go south to where they have the advantage."
] |
How exactly was the French Revolutionary Army able to defend France from being invaded by a coalition consisted of every European country, and also end up expanding French territory?
|
[
"If all men into their 30's were fighting, wouldn't that cause a catastrophic drop in births?"
] |
[
"> And the rocket’s red glare, the bombs bursting in air, Gave proof through the night that our flag was still there. The British navy did not use cannon against Fort Mchenry on the evening that inspired Francis Scott Key. They used rockets and \"bomb\" ships equipped with mortars that fired explosive shells at a high trajectory towards the target. The problem is that the explosive shells, while long ranged, were not so effective against a target like a fort. As Mr. Key noted, Fort Mchenry did not fall to the British. The mortars, which produce shrapnel when they explode, would work better against civilian targets (or infantry) but Baltimore was protected by fortifications armed with cannon that prevented enemy ships from getting close. Land based cannon in a fort can be much larger/longer ranged than those in a ship because one does not have to be concerned with weight on land. In addition, accuracy is better because ground does not move like the decks of a ship."
] |
Is there a measurable increase in salinity of surounding waterways after a particularly cold winter when salt is used in the roadways?
|
[
"Yes. The Chicago area waterways are a good example. Increased chloride levels due to road salt are seen in several waterways in the area. At high levels this can be toxic to aquatic flora and fauna. The levels increase and decrease with the season, but have shown a steady increase once the sixties. [Article with links to studies.](_URL_0_)"
] |
[
"> but in any basic science class one learns that solid ice has a greater volume than water; wouldn't melting the polar ice caps lower the sea level? In any basic science class you should also learn that ice displaces the same volume of water as it would as a liquid, the rest extends above the surface. So theoretically, it would do neither. However, as others note, the problem is that a lot of ice is on land, which melts and runs off into the sea. So what you actually have is the addition of a great amount of liquid water to the ocean."
] |
On restaurant surveys, sometimes the unique code is an absurdly large number, like more than the number of people in the world, by a large margin? Why are these numbers so large?
|
[
"Because it also encodes things such as date, store number etc. It isn't a simple number starting at 1."
] |
[
"For Infrared Remote Controls: The RC5 standard specifies a 5 bit address before the command is send. The NEC standard specifies a 16 bit address before the command is send. So by giving the different appliances different addresses, the remote control only works on one. The \"shortage\" of addresses in RC5 (only 32 different addresses) is overcome by giving different type of appliances a different address since you normally have only one in your local environment: TV gets address 1, radio gets address 2, VCR gets address 3, DVD gets address 4. See also: _URL_0_ For the garage door remote controls: They have a number (with dip switches) in the garage door engine which is the same as the number in your remote control which turns it on/off. For car remote controls: Same as the garage door but you can't set it yourself and hopefully a better random number than the 8 switches in your garage door remote :-)"
] |
After losing blood, how does your body know how much more blood to make?
|
[
"There are two issues: blood volume and red cell count. Your body handles both differently. Blood volume is regulated by blood pressure sensors around your body (especially in the ascending aorta and carotid arteries). When it is high, you release hormones to make you release more fluid in urine. When it is low, you release hormones to conserve fluid loss in urine while also increasing thirst. Red blood cell count is regulated by the amount of oxygen getting to tissues. When it is lower, hormonal signals cause your blood marrow to become more active and produce more than normal (you are always producing some, because they wear out quickly.)"
] |
[
"It's not just the pupil that helps us adjust to bright & dark situations. There is a chemical called Rhodopsin that detects when photons (light) hits it. The light breaks down the Rhodopsin, and it takes a while for it to reform/replenish. So when it's bright and you go into the dark (or stop looking at a bright light when it's dark around you), the time it takes for you to adjust, is just the time that it takes for the Rhodopsin to replenish."
] |
Were there former Roman provinces that believed they were a part of the Roman Empire years after its collapse?
|
[
"> An interesting story recounted by Peter Charanis (a famous Byzantinist who was born in the island of Lemnos in 1908) highlights this: > When the island [Lemnos] was occupied by the Greek navy [in 1912], Greek soldiers were sent to the villages and stationed themselves in the public squares. Some of us children ran to see what these Greek soldiers, these Hellenes looked like. ‘‘What are you looking at?’’ one of them asked. ‘‘At Hellenes,’’ we replied. ‘‘Are you not Hellenes yourselves?’’ he retorted. ‘‘No, we are Romans.\" (Taken from Hellenism in Byzantium by Anthony Kaldellis). I don't think they believed themselves to be a part of the literal empire, but certainly there were still people for a long time who considered themselves to be Roman people."
] |
[
"They tried. Many states had extensive land claims in the west - Connecticut claimed a band of territory bypassing New York and stretching to the Pacific, and sent settlers to what is now Pennsylvania's Wyoming valley and the area around Cleveland in Ohio. Massachusetts made a similar claim to portions of Michigan and western New York, while Virginia claimed the whole Old Northwest (or modern Midwest). In this context of overlapping territorial claims based on unclear colonial charters, which at times even led to bloodshed, and the prospect that those states which had extensive western claims - already the most populous in the union - would gain even more lopsided influence, congress acted to create new states out of most of the disputed territory. (The rest became the western portions of New York and Pennsylvania.)"
] |
Why are we typically so aggravated by those slightly less intelligent than us, yet compassionate to those much less so?
|
[
"Expectations. It's worse with people that I expect to be smart and then do dumb things that I expect they would know better."
] |
[
"\"Just about everyone here\" Where is \"here\" for you? It sounds like your question's premise is based on a small sample set based on personal observation. Before your question is addressed, you should be making sure the premise is valid..."
] |
Why is it feasible for scalpers to buy tickets and then resell them? Couldn't the original ticket seller just sell the tickets at the price the scalpers sell them for?
|
[
"NPR recently did a piece on this. Part of it is if the artist charges $200 then the artist is a money grubber. If a scalper does it, it is expected. Here is the piece. _URL_0_"
] |
[
"People who create software are called \"developers\". To create software programs, they write instructions for computers that is called \"code\". Some developers feel that the best and fastest way to to create better and better programs for everybody is to let anyone who wants to look at this code so they can see how it works, and can add new parts to the code to make the software better. Because you have many developers looking at the code, people who like the free software movement say that \"bugs\", which are problems with the code, get fixed faster. To make money from this, developers charge money to provide special help and support for users of the software. So you can use the software for free, if you are a developer you can modify the software yourself, but if you want to get special help and support you would hire someone who is very familiar with the software, usually one of the developers."
] |
Do different species have different types/levels of hemoglobin and does that different provide an advantage?
|
[
"Not only are variations in haemoglobin observed between species, but also within species. E.g. human foetal haemoglobin is expressed late in foetal development, enabling the developing baby to acquire oxygen from the mother's blood. Also, the bar head goose is a cool example. It's haemoglobin displays an increased affinity for oxygen due to a few amino acid substitutions, enabling them to fly at extreme altitudes."
] |
[
"These sort of questions are really hard to answer under the auspices of \"science\". Someone can probably tell you a story based on a sort of \"evolutionary reasoning\" (and these stories are where a lot of evolutionary studies begin), but unless they can cite a serious research program that has investigated this question, I'd be skeptical of any response you get."
] |
Why does reading in a car cause motion sickness for some people but watching tv does not make those same people sick?
|
[
"Motion sickness is triggered when your eyesight does not agree with your hearing or other senses. In a car, you hear its motion. If you are actually looking at the road, then your eyes see motion and your ears hear and you feel motion, so they agree with each other. However, if you do not look at the road and are instead reading a book, what do you see? The pages of the book. What do you hear and feel? The motion of the car. Because of this, your brain actually thinks that there is some substance or neurotoxin in your system, and thus you will nauseous and queasy. If you are watching TV in a car, you see the TV show or ad instead of the motion outside. However, the difference is that the TV has sound. If the TV is loud enough, then it will dilute the motion of the road and distract your other senses, thus allowing your sight, hearing, and other senses to agree again."
] |
[
"You have a [Vestibulo-ocular reflex](_URL_0_) which automatically corrects your gaze to accommodate any self-initiated head movement. To demonstrate this reflex, nod your head. Your eyes will automatically move counter to the direction of your head in order to keep these words fixed on your retina. Jaw movements during eating usually create some movement of the head, but the vestibulo-ocular reflex compensates for it by moving the eyes as well, so the world appears stable. Crunchy foods, however, may move or shift the jaw in unpredicted ways due to resistance of the hard material--the vestibulo-ocular reflex may not be able to compensate 100% for these unpredicted vibrations of the head, and so you get a slight \"jiggle\" on your retina. Arguably, as H1deki says, this effect is most noticeable with digital displays or other objects with crisp, high-contrast edges. Hope this helps :)"
] |
If we have iron in our blood, can we be lifted with a strong enough magnet?
|
[
"Human have about 4-5 grams of iron through out their entire body. Machines like MRI machines magnetize the human body so that all the water molecules in the body line up and even at that point people aren't attracted to the sides. So probably not."
] |
[
"I've actually built one for a science fair before. I used _URL_0_ as a reference guide: _URL_2_ _URL_1_ It worked, but know going in that you will not get a huge amount thrust. Your setup would probably do better, but it will still most likely not be a lot. What I ended up doing that had a more striking visual effect, was build a sort of moat that I mounted a stationary drive in. Then I was able to put drops of food coloring in and show it getting pushed by the motor."
] |
How meaningful is it to measure the universe's age?
|
[
"While you're right there's not a \"fundamental reference frame,\" the measurement of the age of the universe is meaningful because the expansion is roughly uniform to all space. This is called using a [comoving coordinate system.](_URL_0_) In this, ignoring local motion, most galaxies haved experienced a near identical amount of time since the big bang."
] |
[
"The \"standard model of cosmology\", i.e. [the lambda-CDM model](_URL_0_) treats dark energy as the result of having a non-zero cosmological constant. \"Constant\" being the key word. Ideas like the Big Rip only come about when you imagine a cosmology where the cosmological \"constant\" is actually some elaborate object with behavior and properties that change in time. This is called [quintessence](_URL_1_). In a nutshell, the way quintessence seems to yield a Big Rip is if the fancy structure of the cosmological \"constant\" has some specific mathematical property with a value *below* some number. My point being that there isn't just one theory of a Big Rip cosmology, there are an infinite number where that property takes any particular value provided its below that number. So, it doesn't really make sense to talk about specific behavior as there is no \"specific\" Big Rip theory."
] |
Why does everyone's voice sound different?
|
[
"Everyone's vocal chords are different lengths and the cavities where the sounds bounce are also different sizes."
] |
[
"Same reason why certain food can taste nasty. It’s just not your taste. You’ve adapted to your own style. Nothing wrong with that, imo."
] |
[WW1] What was the distribution of casualties according to the weapons that inflicted them (rifle, machine gun, grenades, artillery, et cetera)?
|
[
"David Holmes' 1985 analysis *Firing Line* concluded that British casualties (deaths and injuries) in World War I broke down to 58.5 percent from artillery (including gas), 39 percent from bullets, 2.2 percent from bombs and grenades, and 0.3 percent from bayonets. John English asserted that artillery accounted for over 60 percent of casualties. It will be impossible to ever get a full and exact accounting, since many of the dead were simply obliterated, either during or after their death."
] |
[
"Off the top of my head, the reforms of Gaius Marius seem to be the most relevant topic to start with. Marius raised armies from the Head Count, which were a teeming mass of the lowest class of citizens in Rome. Previously, armies had been raised from landholders and their sons, but as Rome had more land to protect, it needed greater numbers of men to protect it. His troops performed quite well, but they were supplied by the State rather than out of each soldier's pockets, making warfare much more expensive. This broke the tradition of a three-class army of hastati, principes, and triarii. His soldiers were usually rewarded with land, creating a tradition of strong loyalty in a particular region to one general or faction. It wasn't long before Roman armies became very culturally diverse, with different legions raised from all over the budding empire over the years. This would see Gauls, Numidians, Greeks, etc. serving under Roman colors."
] |
Anonymous is a leaderless decentralized organization. Hen the media reports that Anonymous has issued a statement, where do these statements come from?
|
[
"The easiest way to answer your question is to simply rearrange it slightly: Anyone can issue a statement in the name of Anonymous. If you want to be taken seriously as representing Anonymous you would need to find some way to make your voice louder than one random schlub saying you speak for everyone but any measure other than outing every \"member\" could still theoretically be met with \"well that's just a subset of the group and not everyone\"."
] |
[
"Bell's Theorem put a limit on quantum mechanics. The simplest way of phrasing it is that a \"local hidden variables\" theory cannot explain experimental data. Local means that any sort of signaling happens at the speed of light or slower. Hidden variables means \"maybe there's some other thing that is more fundamentally true that *actually* could tell us what state the particle really was in.\" Broadly speaking, scientists prefer local theories, because faster-than-light transmission of information can be a little dicey (specifically it can talk \"back\" in time). Now it may be that the hidden variable simply cannot be used to carry any measurable information, and thus is totally valid in a physical sense, but it is at this point really that scientists make a philosophical choice, and kind of to each their own. But again, *most* scientists I'm familiar with tend to lean toward true quantum superpositions of states (indeterminacy) and preserving the local behaviour of physics."
] |
Why do injured areas on our body heat up?
|
[
"Due to the inflammatory response. When a part of your body is injured your bodies response is to get blood with healing agents (ie white blood cells and clotting agents) to the point of injury. This increase in blood flow makes the area warmer. _URL_0_"
] |
[
"It's at most *maybe* true. There was a metastudy conducted in India on whether honey was useful for healing burns, and its findings were that honey can be effective for improving the healing of minor, surface burns; its effectiveness was not proven on deeper or more serious burns, however. Since there's only one study, and the results have not been repeated, it's difficult to say how accurate the results were. The study did not explain why it may be effective, but honey does have mild antiseptic and anti-inflammatory properties which *may* help promote healing."
] |
Did members of royal families often marry commoners or is this more of a recent occurrence?
|
[
"That depends on what you mean by \"royalty\" and which time period/geographic area you're discussing. Among the Ancient Romans it was quite common for members of the Imperial family to marry Plebians or non-Romans. However, during the early-Modern and Victorian eras in the West, there was virtually no marriage between Royalty and the non-nobility."
] |
[
"If it's okay, I'd like to ask an add-on question: could anyone, theoretically, do the exam, or was it restricted to the middle classes? I mean, clearly a peasant would probably fail because of their poor education, but were they allowed to try?"
] |
Friday Free-for-All | March 20, 2015
|
[
"I have some bad news. I don't want to go into too much detail, but my anonymity has been compromised. A post I made (which I deleted, so don't bother looking) has been made public along with my identity. It's worked its way to some of my colleagues, and caused me a great deal of trouble. So long story short, I have to delete this account. Hopefully I'll be able to return at some point under a different name. So if you see another user some time down the road with a similar flair, it's probably me. If you recognize me, I'd ask you to not explicitly point it out as I don't want this to happen again. I'm going to miss you guys. Hopefully this break won't be permanent."
] |
[
"Here's an ancient forum post from 1997 that you might find interesting...though you actually have to click the links to navigate. Also, I wonder if that's _the_ John Conway leaving replies there... _URL_0_"
] |
Did ancient temples really have depressible stone panels that would send out darts or reveal hidden passages?
|
[
"Here's a discussion from 3 years ago: [Is there any historical precedent for a pre-modern culture constructing elaborate mechanical traps \\(as seen in many films such as \"Goonies\" or in various \"Indiana Jones\" films\\) that are disarmable by an artifact or by a sequence of actions? Where does this common film trope come from?](_URL_1_) There are a couple similar topics from the FAQ section on [Monuments and Architecture](_URL_0_)."
] |
[
"That mosque is not in Timbuktu. It is the [Great Mosque of Djenne](_URL_0_), in the city of Djenne which is about 500 km south-west of Timbuktu in Mali. Anyhow, those are wooden timbers called *toron*. They are used to [support scaffolding]( _URL_2_) when adobe is reapplied to the exterior of the mosque, or when repairs are needed. These *toron* are ubiquitous in many large mosques in West Africa, including the [Sankore mosque](_URL_5_) and [Djinguereber mosque](_URL_4_), both in Timbuktu, and the [Great Mosque of Mopti](_URL_3_) and even smaller mosques have begun to [use them as a stylistic element](_URL_1_)."
] |
Do dogs eventually recognize themselves in mirrors, or do they just get used to having another "dog" around?
|
[
"BA - Anthropology, UIUC [non-expert, but decent underlying knowledge anyway] Non-human primates have shown differing levels of ability to become aware of the self in a mirror reflection. Apes pick up on it rather quickly. Lemurs, on the other hand, show an (almost?) complete inability to recognize the self. Some dolphins/killer whales also pass the mirror test. If there's a dog expert out there, could he answer my hypothetical: since dogs are more reliant on sound and (especially) scent, as opposed to vision, would the mirror matter less because eventually the dog would realize that it isn't *smelling* another dog in the room, and thus the mirror isn't important to him?"
] |
[
"A few things to realize before trying to draw conclusions like this: * Science is an evolving process that doesn't end with a single study. One study's results could be refined or contradicted by other studies, and it takes multiple iterations to suss out the truth. * Science journalism is terrible. University PR staff write terrible press releases that misunderstand the science. Journalists without science training misunderstand the press releases, and write terrible articles. Editors who don't care about anything beyond selling ads misconstrue articles and write terrible headlines. * There are a lot of garbage products sold for pets that don't really work."
] |
How do TV networks decide what episodes of a show to play?
|
[
"The networks/stations own the rights to air the shows, but the episode orders come from the syndication companies. So The Big Bang Theory is on Peachtree TV in Atlanta, but Warner Brothers is the Syndicator, and they provide the episodes and the order. The reason 2 parters are run out of sequence on back to back shows is because the first half hour is usually the \"first run\" order and the next half hour is the \"second run.\" I believe it was a holdover from days when local stations and cable networks would buy the same shows, but have different runs, so they wouldn't compete with the same episodes as another station."
] |
[
"I was curious about this as well, so I did some google-fu and found some results. This is all secondhand so take it with a grain of salt. It seems that the stations contract survey companies to get a rough estimate based on a sample population in the area. Arbitron is one of those companies. How do they do it? They ask people to maintain a diary. Seriously. \"Selecting a random sample of a population in roughly 100 metros throughout the United States four times a year. An additional 200 markets are surveyed in the Spring and Fall. People in the sample are asked to maintain a written diary describing each radio program listened to. Each selected household agreeing to participate is provided a diary for each member aged 12 and older… A new random sample is selected weekly…\" There's also something called a Portable People Meter, which is a microphone placed by a radio that can detect what the person is listening to through hidden audio tones in the broadcast. This is a little cooler. _URL_0_ Source: _URL_1_"
] |
How did they put cables undersea in 1854? And how would they do it now?
|
[
"Big [cable-laying ships](_URL_0_). Which is exactly how they do it today. The cables are rather more sophisticated today! EDIT - oh, and they would have been telegraph connections, not telephone."
] |
[
"Because there are no laws that govern the entirety of the internet. There are laws in countries that limit what the people living inside of its borders can do with the internet, but those laws dont apply if you arent in that country. All pirate bay has to do to stay operational is to find a country that doesn't care about copyright and doesn't care enough about the world stage to extradite them. Russia or SE Asian countries usually do the job quite well. The best part is that the owners dont even have to live in those countries, they just have to host the servers in those countries and the likely hood of an investigation finding anything is near zero."
] |
What part of the sleep cycle cause "morning wood" and why does it cause arousal? Is there a similar phenomenon that women experience?
|
[
"To my knowledge, as a vagina-haver, we don't have anything similar to morning wood. But our urethra is also separate from our sex organs."
] |
[
"From the exact same XKCD article that you linked: > (Climates can be hard to predict—for example, in our world, Somalia and French Guiana both sit on the equator, at the eastern coast of a continent, and seem like they should both receive a tropical sea breeze. But coastal French Guiana is dense rain forest while coastal Somalia is an arid desert. The explanation involves the monsoon cycle.) So, I suspect the answer involves the monsoon cycle..."
] |
How is the landing gear of a plane designed to withhold this much force?
|
[
"Why: Because this is a failure mode the engineers specifically design for. How: They had to burn off all the fuel and land on fumes, and land with the nose up as long as possible, and still most of the wheel ended up decorating about a mile or two of the tarmac."
] |
[
"It's how the bricks are made. The LEGO term is \"clutch power\". You have the top cylinders on the top of the bricks and then on the inside you have inner cylinders. They do give out but after a LONG time. Here's an example _URL_0_"
] |
why do computer screens look weird on camera?
|
[
"Because the screen refreshes at a faster rate than the camera records. Same reason LED headlights seem to blink in videos."
] |
[
"My guess? When you're dealing with a lot of makeup, prosthesis, special effects its easier to hide flaws. You can see acne under makeup in high def, you couldn't really see that back in the day. Just a guess."
] |
What is Voyager 1's trajectory in this gif?
|
[
"Those photos were taken over many days, and the camera was rotated to track the planet as it approached it. That said, it did fly pretty close to Jupiter, coming within some 174 thousand miles of the surface."
] |
[
"You can't calculate it. You have to determine it experimentally. The first measurement was done by Cavendish using a very sensitive torsional beam: _URL_0_"
] |
Viruses display a sort of 'intelligent' desire for survival and reproduction - even though they don't fit the traits required for a living organism, why don't we classify them as alive?
|
[
"Viruses can't reproduce in isolation. They need some other host to glom off of. They're different from other parasitic organisms because they actually need another living thing to reproduce, as opposed to feeding off of another living thing's nutrients. Intestinal flora (the bacteria in your gut), for example, would happily colonize a petri dish if you gave them the right mix of nutrients. A virus needs a host cell in order to reproduce, though, not just the nutrients that the host cell provides. I guess you can argue that it's an arbitrary distinction, but that's the distinction that has been made."
] |
[
"The biggest definitions of life mostly involve self replication and reacting to the environment. Given that the definition of life is so fuzzy/arbitrary, anything that does the same thing as life by definition is life."
] |
why do we bury people 6 feet under?
|
[
"Six feet is deep enough to make it too hard for animals to dig up graves, but not so deep that decaying bodies contaminate the water supply. In places where the water table is very high, like New Orleans, Louisiana, underground graves are not practical, so they build above-ground mausoleums to store the dead."
] |
[
"Look at it like a chess board: After 100+ moves, it's hard to set every step back until you're in the start position. It's easier to remove all the pieces from the board and start all over. ^This ^was ^explained ^before"
] |
Why did America experience such a sea change in its opinion on gay marriage over the past 25 years?
|
[
"There was a group of gentlemen who got together one day and decided to advance the cause of gay rights. They're movement is called the Bravo! Network."
] |
[
"Exposure to different kinds of people and ways of living vs rural bubbles. Notice that ports and hubs along the water tend to be the most liberal often having to do a lot with immigration and travel."
] |
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