question stringlengths 3 301 | answer stringlengths 9 26.1k | context list |
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what is it about cast iron that makes it a "true non-stick surface"? | Basically, the "burnt" carbon in the oil fills all the little cracks in the iron, making it smoother. That's why you don't wash them with soap, so the carbon won't come out. If you have to re-season, or are starting with a new one, you'll have to coat it in oil and bake it in the oven 'til it smokes, then polish it d... | [
"Cast iron is a brittle form of iron which is weaker in tension than in compression. It has a relatively low melting point, good fluidity, castability, excellent machinability and wear resistance. Though almost entirely replaced by steel in building structures, cast irons have become an engineering material with a ... |
why can we have heaters but not coolers? | To put it very simply, it's because heat is a thing whereas cold is a lack of a thing. You can generate heat through various processes of converting one energy type (electrical energy or chemical energy) into heat energy. You can't generate cold because cold is just a lack of heat. So the only way to make something col... | [
"Some modern coolers are thermoelectric, plugging into a car's cigarette lighter socket. Rather than using a compressor and refrigerant such as a refrigerator or other heat pump, these use the Peltier effect along with an external fan to draw away the heat. By reversing the current, this concept can also heat the c... |
Why are people in the military refered to by their last name instead of their first name? | Tradition, based on maintaining formality actually. First names breed familiarity. Must be professional (or appear to be) above all else.
Also, I was the only person in my company with my last name while there were several other guys with the same first name as me. | [
"Regardless of origins, many names that are now considered first names in the U.S. have origins as surnames. Names like Riley, Parker, Cooper, Madison, Morgan, Cameron, and Harper originated as surnames. Names that originate as surnames typically start out their lifespan as androgynous names before developing a com... |
What would be the most effective man-portable modern weapon to bring into combat against pre-firearms battle formations? | Probably the [Davy Crockett](_URL_0_), a portable nuclear weapon system. | [
"Small arms, such as the M249 SAW, have been employed on a squad level to provide an overwhelming volume of fire in relatively close quarters situations (within 100-300 yds). The idea is that a large volume of accurate suppressive fire will immobilize the enemy, degrading their ability to perform. In addition, gren... |
why is it so difficult to memorize some of the things which we really need to whereas somethings we easily memorize without even putting in the effort to do so? | The amount of interest one has in the endeavor. Say for instance, as a language teacher, you’re teaching students that are either very keen on the subject or resistant to it due to the amount of interest they have in the language. The students who are more interested in the subject will always do better than the studen... | [
"Memorization, the deliberate mental process or storing information for future recall, is one of the most common learning practices. Since the information must be stored before it is actually needed, learners can become frustrated when they are unable to recall the information when it is needed.\n",
"Human beings... |
why does it seem that every company that updates their user interface makes it worse? | Because it changes from what you're used to, I'm sure if reddit changed from the new version to the old version there would be a lot more complaints. | [
"A side effect of this is that software maintenance gets more complex, because software updates need to be validated and errors in the upgrade process may lead to a false-positive triggering of the protection mechanism.\n",
"Redesigning business processes is more sensible for causing resistance in the usage of pr... |
if passwords are stored as hashes why is it more secure to have passwords with numbers, capital letters, etc. | If the password database is stolen, or a security hole is discovered that lets the attacker try tons of combinations, they will probably immediately try a dictionary attack.
They'll check to see if any of the hashed combinations match common words and common passwords. This means that some will probably immediately fa... | [
"But passwords are typically not safe to use as keys for standalone security systems (e.g., encryption systems) that expose data to enable offline password guessing by an attacker. Passphrases are theoretically stronger, and so should make a better choice in these cases. First, they usually are (and always should b... |
can poisonious creatures poison themselves, and if they can be poisoned is tolerance higher for them | Poisonous or venomous? Poisonous creatures you can’t eat. Venomous ones use poison on you (usually with bite). | [
"Some rodenticides are lethal after one exposure while others require more than one. Rodents are disinclined to gorge on an unknown food (perhaps reflecting an adaptation to their inability to vomit), preferring to sample, wait and observe whether it makes them or other rats sick. This phenomenon of poison shyness ... |
how is it that lower class people support the wealth gap/top 1% against their own self interest? | TO quote John Steinbeck: "Socialism never took root in America because the poor see themselves not as an exploited proletariat but as temporarily embarrassed millionaires."
You can't vote against the oppressors if your one secret wish is to join them one day. | [
"In his 2007 book \"\", George Mason University economist Bryan Caplan argued that, all else equal, voters do not, in fact, choose policies based on self-interest. The rich are not more likely to support policies that personally benefit them, like lower marginal rates, and the poor are not more likely to oppose wel... |
what does "bulking" (for bodybuilders) do to your body in a biological sense? | You're eating to give your body an abundance of the materials it needs to make muscle. You will eat more calories than you burn (so you aren't using up stored energy) and you'll eat a surplus of proteins (so you have enough amino acids which are the building blocks of proteins). You do this so when you work out your ... | [
"The general strategy adopted by most present-day competitive bodybuilders is to make muscle gains for most of the year (known as the \"off-season\") and, approximately 12–14 weeks from competition, lose a maximum of body fat (referred to as \"cutting\") while preserving as much muscular mass as possible. The bulki... |
How can ants count their steps? We've developed numbers as a system of organization and measurement, so we can literally speak "1, 2, 3" but how can an insect keep track of the amount of steps it has taken? | The authors of the study that I believe you are [referring](_URL_0_) to weren't sure what internal mechanism is guiding it. And this paper was put out nine years ago and I don't see anything on it since then. However insects and animals in general are capable of doing things we think have to think about (counting for... | [
"Ants were shown to be able to count up to 20 and add and subtract numbers within 5. In highly social species such as red wood ants scouting individuals can transfer to foragers the information about the number of branches of a special “counting maze” they had to go to in order to obtain syrup. The findings concern... |
when a gaming company develops a new 'engine', what have they actually done? | So I have no experience with game programming in particular, but a lot of experience with other types of programming and with physics.
Basically when you write good code you reuse a lot of the old code. So in time this process has been streamlined into "libraries" or a large groups of code which works well together. T... | [
"As of 2014, Capcom's stance on the future of the engine is that while it will continue to be used to create games for the seventh generation of video game consoles, smartphones and handhelds, Panta Rhei and the RE Engine, which was used to develop \"\", are intended to be MT Framework's successors for developing g... |
why does the writing on tires in motorsport appear to spin in different directions at different speeds? | What you are watching is a recording made by a camera. The camera shoots a certain number of frames per second, and each frame is a snapshot of what is visible at that moment.
If the wheel happens to rotate through a little less than a full turn, say 350 degrees, in the time between one frame and the next, then this w... | [
"The intention of Ackermann geometry is to avoid the need for tyres to slip sideways when following the path around a curve. The geometrical solution to this is for all wheels to have their axles arranged as radii of circles with a common centre point. As the rear wheels are fixed, this centre point must be on a li... |
why can't we use human poop as fertilizer? | Ever heard of *night soil*?
> The reuse of feces as fertilizer was common in Japan. Waste products of rich people were sold at higher prices because their diet was better; therefore, more nutrients remained in their waste. Various historic documents dating from the 9th century detail the disposal procedures for toile... | [
"Human excreta may be attractive as fertilizer because of the high demand for fertilizer and the relative availability of the material to create night soil. In areas where native soil is of poor quality, the local population may weigh the risk of using night soil.\n",
"Urine can also be used safely as a source of... |
In terms of evolution, why is vitamin D synthesis dependent on exposure to sunlight? | I'm not sure which direction you are thinking about this from, so I will answer both questions simplistically. Feel free to ask for clarification.
1. Why haven't we evolved to produce vitamin D without sunlight?
All organisms which use the chemical (as far as I'm aware) from phytoplankton to mushrooms to mammals synt... | [
"Synthesis of vitamin D in nature is dependent on the presence of UV radiation and subsequent activation in liver and in kidney. Many animals synthesize vitamin D from 7-dehydrocholesterol, and many fungi synthesize vitamin D from ergosterol.\n",
"Vitamin D is produced photochemically from 7-dehydrocholesterol in... |
why is it that sometimes i can be more tired after a long day at school than a long day doing physical labour. | The brain consumes more calories than the muscles in your core.
| [
"Physical fatigue, or muscle fatigue, is the temporary physical inability of muscles to perform optimally. The onset of muscle fatigue during physical activity is gradual, and depends upon an individual's level of physical fitness – other factors include sleep deprivation and overall health. Fatigue can be reversed... |
During the glorious revolution of 1689 William and Mary of Orange became the king and queen of England, Scotland, etc. But did they keep their power as ruler of the Netherlands? If so, does that mean that the UK and the Netherlands were the same country for some time? | First question: Yes, William (not Mary) maintained his position as Stadtholder of the Dutch Republic. It's worth nothing that though officially dual monarchs of England, in practice William took the leading role even while Mary was still alive.
Second question: You can quibble about this, but I'd say in principle, no.... | [
"From 1603, Scotland and England shared the same monarch in a personal union when James VI of Scotland was declared King of England and Ireland in what was known as the Union of the Crowns. After James VII of Scotland (II of England) was deposed in 1688 amid Catholic-Protestant disputes, and as the line of Protesta... |
since our cells are always multiplying, does a 90 year old have more dna in their body than a newborn? | Yes, an adult has more cells, thus more DNA, than a newborn.
But once you reach full size, you stop increasing the number of cells. New ones are born and old ones die. So a 90 year old has about the same amount of cells and DNA as a 20 year old. | [
"In a study that analyzed the complete DNA methylomes of CD4 T cells in a newborn, a 26 years old individual and a 103 years old individual was observed that the loss of methylation is proportional to age. Hypomethylated CpGs observed in the centenarian DNAs compared with the neonates covered all genomic compartmen... |
how does the hard disk save my data, when my computer is shut down? | Through magnetism.
Imagine that there are billions of small magnets inside your hard drive. When your computer writes something, it arranges those magnets in a particular way. You need electricity to do that. But once you are done, the magnets will stay in their place regardless of whether you have power or not. | [
"Normally, when the computer is shutting down, every mounted storage will undergo an unmounting process to ensure that all queued data got written, and to preserve integrity of file system structure on the media.\n",
"Software can \"partition\" a portion of a computer's RAM, allowing it to act as a much faster ha... |
why doesn't apple broadcast their product announcements | Apple usually provides a video of the event on their website that evening or the next day. The reason they don't broadcast it live or provide the video earlier is because they'd essentially be stealing traffic from the tech blogs, which they want to maintain a good relationship with. | [
"Apple debuted a new series of ads produced by TBWA\\Media Arts Lab during television broadcasts of the 2012 Summer Olympics opening ceremony. The ads portrayed people in everyday situations being assisted by an employee from the company's Genius Bars. The ads were widely criticized, with some, including former TBW... |
Is there evidence surgical masks being worn by people who are ill significantly help limit infection of others? | "For many years, scientists weren't sure if wearing a mask was effective at preventing the spread of viruses. However, recent studies suggest that they can help.
First, a 2008 study published in the International Journal of Infectious Diseases concluded that when used correctly, masks are highly effective in preventin... | [
"Simple surgical masks protect wearers from being splashed in the mouth with body fluids, and prevent transmission of body fluids from the wearer to others, e.g. the patient. They also remind wearers not to touch their mouth or nose, which could otherwise transfer viruses and bacteria after having touched a contami... |
Help me identify a dogtag I found | This is almost guaranteed to be some sort of civilian copy. First, I have never seen a WWII era dog tag that looked like that. Second, there is no reason to have rank on a dog tag. Ranks change, especially during war. | [
"\"Dog tag\" is an informal but common term for a specific type of identification tag worn by military personnel. The tags' primary use is for the identification of dead and wounded soldiers; as such, they have personal information about the soldiers written on them, and convey essential basic medical information s... |
what do real spies do? how are they recruited? do they actually have the kind of gadgets we see in bond films? | You're not going to get an answer here. If anyone on reddit knows anything about this, they are a spy. If they are a spy, they will not tell you.
This is our daily dilemma. | [
"\"SpyParty\" is played between two players: one plays as the \"spy\" and the other is the \"sniper\". The spy is given control of one of several avatars at a high society cocktail party, and must complete a pre-determined number of missions within a time limit while attempting to blend in with the other AI-control... |
i'm curious, why don't humans just 'taste' unhealthy food? why do we have to swallow it? | Because the part of your brain that controls the feeling of being full (satiety), the [arcuate nucleus](_URL_0_), probably wouldn't be stimulated.
Also, it's not that those foods themselves are intrinsically unhealthy. If you're on a desert island or, a human who sucks at hunting mammoth, those foods would be perfectl... | [
"Taste aversion is fairly common in humans. When humans eat bad food (e.g., spoiled meat) and get sick, they may find that food aversive until extinction occurs, if ever. Also, as in nature, a food does not have to \"cause\" the sickness for it to become aversive. A human who eats sushi for the first time and who h... |
how do executives hold board of director positions at multiple fortune 500 companies? | The Board only meets occasionally to vote on more important matters. They don't really deal with day to day affairs like the CEO does. | [
"The company is run by a board of directors made up of mostly company outsiders, as is customary for publicly traded companies. Members of the board of directors as of June 2014 are: Robert W. Alspaugh(\"Director\"), Karen Austin(\"Director\"), Paul Galant(\"Director; Chief Executive Officer\"), Alex W. (Pete) Hart... |
Why is the popular view in Western pop culture that the German army fought a "clean war" on the Eastern Front of WWII, independent of the genocidal policies of the Nazi regime? How did a romantic view of the German army on the Eastern Front become mainstream? | From an [older answer](_URL_0_) where /u/Georgy_K_Zhukov also weighed in on the subject matter:
The clean Wehrmacht myth was something that was advanced by both the (West)German and the Western Allied governments after the war within the context of the budding Cold War. There was it's own Eastern German version of it ... | [
"The Myth of the Eastern Front: The Nazi-Soviet War in American Popular Culture is a 2008 book by the American historians Ronald Smelser and Edward J. Davies of the University of Utah. It discusses perceptions of the Eastern Front of World War II in the United States in the context of historical revisionism. The bo... |
How do I hear music in white noise? | White noise contains thousands of different frequencies. Your mind can subconsciously focus on certain frequencies, sometimes making up what you perceive as tunes. Also, take a look at [auditory hallucination](_URL_0_). | [
"White noise is commonly used in the production of electronic music, usually either directly or as an input for a filter to create other types of noise signal. It is used extensively in audio synthesis, typically to recreate percussive instruments such as cymbals or snare drums which have high noise content in thei... |
Can Solar Panels be charged with Nuclear Radiation? | You can use the decay heat to produce electricity - [radioisotope thermoelectric generators](_URL_0_) (RTGs) do that.
For beta decays you can directly use the radiation and let the electrons fly through a potential difference - [betavoltaics](_URL_1_).
You could in principle let ionizing radiation pass through a mate... | [
"The radiation safety is arranged and implemented to prevent inadmissible impacts caused by ionizing radiation sources on the materials, population and environment in the area that surrounds a Nuclear power plant. \n",
"Current nuclear power generators are approximately half the weight of solar panels per watt of... |
How can something be "10,000 times colder than the vacuum of space"? | A true vacuum doesn't have a meaningful temperature, but when they say "the vacuum of space", they are probably referring to the cosmic microwave background radiation, which has a temperature of about 2.7 Kelvin. | [
"Outer space has very low density and pressure, and is the closest physical approximation of a perfect vacuum. But no vacuum is truly perfect, not even in interstellar space, where there are still a few hydrogen atoms per cubic meter.\n",
"Theoretically, the coldest a system can be is when its temperature is abso... |
how does the united states pay for its' wars? | Taxes. The US federal government gets over $3 trillion a year. | [
"The United States needed $3.1 billion to pay for the immense armies and fleets raised to fight the Civil War — over $400 million just in 1862. The largest tax sum by far came from new excise taxes—a sort of value added tax—that was imposed on every sort of manufactured item. Second came much higher tariffs, throug... |
why don’t tornadoes develop in extremely urban areas with skyscrapers such as new york city or chicago? | _URL_0_
Basically not alot of major cities lie in tornado zones so its already unlikely | [
"The misconception, like most, has a small basis in truth. Research has been done in a few metropolitan areas suggesting that the urban heat island effect may discourage the formation of weak tornadoes in city centers, due to turbulent warm air disrupting their formation. This does not apply to significant tornadoe... |
How do we KNOW that a comet, like Halleys, is the same comet each time it comes around (This question from my family after watching Episode 3 of Cosmos) ? | Because we can predict their passing in the sky with accuracy (diabolical accuracy might I add)
That is the power of Newton's mathematics. (Next time your kids ask you what is math good for this is a good example: math can explain and predict basically everything that is going on in the universe)
By calculating it's... | [
"Halley's returns to the inner Solar System have been observed and recorded by astronomers since at least 240 BC. Clear records of the comet's appearances were made by Chinese, Babylonian, and medieval European chroniclers, but, at those times, were not recognized as reappearances of the same object. The comet's pe... |
the legality of the pirate bay | The basic moral/legal question is if a technology that makes committing a crime easy can be held liable for that crime. TPB doesn't commit any crimes, but they enable others to do so. An offline allegory would be an inventor of perfect lockpicks that could open any lock. Would he be at least partially responsible for t... | [
"The Pirate Bay has sparked controversies and discussion about legal aspects of file sharing, copyright, and civil liberties and has become a platform for political initiatives against established intellectual property laws and a central figure in an anti-copyright movement. The website faced several shutdowns and ... |
Why don't electrons all fly off their orbits considering how much energy is present in everyday contexts? | What grade are you in where this topic has come up? The abstraction of the electron as an actual particle making circular orbits around the atom's nucleus is a poor and inaccurate model that can not be used to meaningfully answer this question. At the scale we are talking about, you shouldn't use the math of Newtonia... | [
"Electrons do not have definite orbits, or sharply defined ranges. Rather, their positions must be described as probability distributions that taper off gradually as one moves away from the nucleus, without a sharp cutoff. Moreover, in condensed matter and molecules, the electron clouds of the atoms usually overlap... |
The link between The Great War, WWII and the Cold War | Alright, I'll take this from the top in the most detailed way I can. I feel it unnecessary to cite sources, as I believe most of this is common knowledge, and a quick Google search will prove me right.
So WWI started because Archduke Franz Ferdinand of Austria-Hungary was assassinated by Gavrilo Princip, a Serbian na... | [
"The Aftermath of World War II was the beginning of a new era, defined by the decline of all European colonial empires and simultaneous rise of two superpowers: the Soviet Union (USSR) and the United States (USA). Allies during World War II, the US and the USSR became competitors on the world stage and engaged in t... |
how do boxtops fund education? | School collects box tops & sends them to the company. The company sends the school money.
The idea is that people will buy more products from the company if they know it'll help the local schools. It's just an advertising campaign. | [
"The School Fund is a person-to-person crowdfunding platform and nonprofit organization through which donors directly contribute to educational scholarships for low-income students in countries that do not offer free, public secondary school. Like other civic crowdfunding platforms, through The School Fund, large n... |
Refining particle collision calculations | 1. 1.15*10^(11) protons are in each proton bunch ([source 1](_URL_0_))
1. Just because there are hundreds of billions protons, they do not all collide in each bunch crossing. Each bunch crossing will see somewhere between 0 and 30 collisions. If multiple collisions occur, most will be glancing collisions, and in gener... | [
"Each particle-target collision is called an \"event\". An elaborate data acquisition system records each event measured by the particle detectors, up to several thousand events per second on average. This data is then transferred to a \"farm\" of computing processors. Teams of physicists analyze the events, lookin... |
Why is it so difficult to find a map of the papal states? | I searched "papal states map" on Bing, went to images, and saw one without scrolling. It's an 1847 2nd Edition map, link if you'd like.
_URL_0_
They're not individually labelled on the maps because the maps are generally larger scale, and printing the names would be a gigantic hassle.
Edit: I found some other maps,... | [
"The map is a 13th-century parchment copy of a possible Roman original. It covers Europe (without the Iberian Peninsula and the British Isles), North Africa, and parts of Asia, including the Middle East, Persia, and India. According to one hypothesis, the existing map is based on a document of the 4th or 5th centur... |
- why do some computer programs let me alt+tab seamlessly to another application, and some will crash or even force me to reboot if i try to use alt+tab? | Programs don't receive the command. Alt+Tab is a system interrupt command and is directly interpreted by the operating system without being passed to the programs. Certain full-screen only applications and may not like it much because they are not designed to run in the background, which can cause their graphics or p... | [
"If is disabled, attempting an Alt code may cause unexpected results in some applications, due to the controls used on the same key. For example, + can be taken as +, causing a web browser to go back one page. \n",
"Because the operating system and applications all share a single memory space, it is possible for ... |
how can a bank determine fraudulent activity from a single transaction? | In current day banking it's just machine learning. They fed an AI with a bunch of labeled data, and now it's able to say which transaction is likely fraudulent and which is not; just like the YouTube algorithm showing you stuff you probably want to click on.
Noone knows what exactly the algorithm is thinking, just tha... | [
"Banks have the option of performing fraud detection either in real time or once every 24 hours. If a bank puts the liability of the small business account onto the customer, then it should be assumed that fraud detection is done once every 24 hours. If a bank assumes the liability for fraud on a small business acc... |
Can modern chemistry produce gold? | We can, it's just highly, highly impractical. Creating diamond is relatively straightforward, we just have to convert carbon from one form to another. For that all you have to do is to [take cheap graphite, heat it up under high pressures](_URL_2_), and voilà, you get [diamond.](_URL_1_)
Creating gold on the other han... | [
"The production of gold from a more common element, such as lead, has long been a subject of human inquiry, and the ancient and medieval discipline of alchemy often focused on it; however, the transmutation of the chemical elements did not become possible until the understanding of nuclear physics in the 20th centu... |
why is the color red used for the red light district? | No. It has to do with old world Asian influences actually iirc.
The streets with brothels used to use lanterns with red paper to mark the brothels, they were usually all in one part of town so criminal activity would largely be limited to the bars and whore houses and the "police" of their respective time periods coul... | [
"Red lights signify a risk-to-life situation, and are used alone by Aviation Rescue Fire Fighting (ARFF), Mines Rescue, Western Power, Red Cross blood/organ transport, St John Ambulance Service and all WA State Emergency Service that do not have Red and Blue. Red lighting used to be in use for fire engines, ambulan... |
when and why did corsets move away from being common place and become more of a sexual statement? | Corsets really made some sense in an era of multiple pregnancies; they help hold a woman together, keep the weight of her skirts off her hipbones, and provide excellent back support. The problem arises when the fashion is for tight-lacing that also distorts the back, which was the case in the 1890s.
But really, the... | [
"Although the corset had not been a part of mainstream fashion since the early 1900s, it continued to exist in the fetish and pornographic cultures used for S&M role-play. The sexual liberation movement of 1968 began the re-appropriation of the corset as a symbol of rebellion and \"sexual perversity\" by young wome... |
how were the first people able to access and use iron ore mines to make things? | There is a thing called Bog Iron that is just lying around in bogs.
It comes from water that has Iron in it and through some chemical processes it turns into a lump of Iron ore.
You would walk around with a stick poking the ground until you felt something rocky.
You would also find Iron from meteors. | [
"The area is very rich in minerals. Mining has been focused on iron ore for centuries but other ores has been mined as well. Most mines are now closed, but in the 1970s many mines were still in operation. The earliest signs of iron making dates back to 400 BC while industrial scale activities dates back to the 17th... |
Otto von Bismarck...man of war or man of peace? | There is a problem I have with the answers given until now. They up until now follow totally the "Bismarck the puppetmaster who set everything up to the Franco-Prussian-War to unite Germany" reasoning. There are really some points which doesn't fit into that.
Bismarck had mostly only one thing in mind, and that was B... | [
"Georg von Bismarck (15 February 1891 – 31 August 1942) was a German general during World War II who commanded several divisions. He was a recipient of the Knight's Cross of the Iron Cross of Nazi Germany.\n",
"Hans-Georg von Seidel (11 November 1891 – 10 November 1955) was a German military leader who served in ... |
the group 'anonymous' and some of the major things they have done. | Here you go OP:
Anonymous is a broad term used to refer to members of the 4chan community. (Used in the singular usually as Anon).
The reason for this came from the posting style of 4chan. 4chan has no registration, so each post is individual. When making a post you had the option of inserting a name if you wanted, ... | [
"Anonymous (used as a mass noun) is a loosely associated international network of activist and hacktivist entities. A website nominally associated with the group describes it as \"an internet gathering\" with \"a very loose and decentralized command structure that operates on ideas rather than directives\". The gro... |
History of Science | Was the creation of nuclear weaponry a direct result of the pressures from WWII, or was it simply the natural advancement of weapon technology that would have happened otherwise? | [
"BULLET::::- H. Floris Cohen, \"The Scientific Revolution: A Historiographical Inquiry\", University of Chicago Press 1994 - Discussion on the origins of modern science has been going on for more than two hundred years. Cohen provides an excellent overview.\n",
"\"Science in History\" (1954) is a monumental four-... |
How strong is a single carbon nanotube? | From what I can find, a carbon nanotube has a diameter of about 50 nm. The highest theoretical strength is 126.2 GPa, but actual testing gives the much weaker strength of 13-53 GPa, presumably to imperfections and not having the best structure. Let's go with 53 GPa. Using that, and assuming a square packing, each nanot... | [
"Carbon nanotubes are the strongest and stiffest materials yet discovered in terms of tensile strength and elastic modulus respectively. This strength results from the covalent sp bonds formed between the individual carbon atoms. In 2000, a multi-walled carbon nanotube was tested to have a tensile strength of 63 gi... |
What Che Guevara really thought about homosexuality, race, diversity and democracy? | [I'd recommend this AskHistorians thread](_URL_0_) which answers many parts of your questions. | [
"Castro is reported to once have asserted that, \"in the country[side], there are no homosexuals\", before claiming in 1992 that homosexuality is a \"natural human tendency that must simply be respected\". Another source reports Castro as having denounced \"maricones\" (\"faggots\") as \"agents of imperialism\". Ca... |
i flip a coin 3 times. the first two times i get heads, why is there a 50/50 chance i'll flip heads again but a 12.5% chance i'll flip 3 heads in a row? | The reason that the previous coin tosses do not influence the third coin is because outcomes of a coin toss are independent. Each and every coin toss for any fair coin will have a 50/50 chance of showing heads. This is because the other coins have no way of influencing the third toss. The reason the probability of flip... | [
"If after tossing four heads in a row, the next coin toss also came up heads, it would complete a run of five successive heads. Since the probability of a run of five successive heads is (one in thirty-two), a person might believe that the next flip would be more likely to come up tails rather than heads again. Thi... |
Why did some animals evolve to lay eggs? Wouldn't it be more energy-efficient to have eggs inside your body instead of laying them and then having to care for them (like chicken do for example)? | First a small evolutionary history quibble: egg-laying evolved before internal fertilization and egg-bearing (leading to live birth) did! Think of how salmon breed: the female lays a bunch of unfertilized eggs, then the male comes and fertilizes them. This is the "ancestral condition" from which internal fertilization ... | [
"It has been suggested that trophic egg-laying evolved as a consequence of limited egg size, since larger eggs with more nutrient supply would require the mother to have a larger body size. Thus, the production of more eggs, some of which are not intended to reach maturity. It is relatively simple for the mother to... |
what is the 2nd world | During the Cold War, the Second World referred to either the Soviet Union and its allies, or all Communist countries. Depends on who you ask. | [
"The First world comprises the US and the USSR, the superpower countries respectively engaged in imperialism and in social imperialism. The Second world comprises Japan and Canada, Europe and the countries of the global North–South divide. The Third world comprises the countries of Africa, Latin America, and contin... |
Reddit, what's the best way to get a full read on Russian history? | Unfortunately, there is no one book or resource that can encapsulate the incredibly diverse and variegated history of Russia. To get something approaching a full read, one should read multiple books and articles. One of the better ways online to find out which books to read is to examine the reading lists produced for ... | [
"The encyclopedia's Chief Editorial Board and Advisory board sought input from the general public. The entry list was sent to universities, scientific institutions, museums, and private specialists in every field. More than 50,000 suggestions were received and many additions were made. Scholars believe that the Enc... |
Were there any major naval battles during the 30 years war? | The answer to this, like most 30 years war questions, is yes, maybe, sort of, and after a fashion but it wasn't really what you think. There were a lot of Naval engagements between Spain and the Dutch during the period of the Thirty Years War, and both of them were major players in that conflict (except when only one o... | [
"The Battle of Arnemuiden was a naval battle fought on 23 September 1338 at the start of the Hundred Years' War between England and France. It was the first naval battle of the Hundred Years' War and the first recorded European naval battle using artillery, as the English ship \"Christopher\" had three cannons and ... |
What is that 'curtain' of gaseous stuff that we usually see falling down the sides of a rocket during launch ? | ice- most modern rockets are hydrogen based. And are propelled by large amounts of liquid oxygen in hydrogen, making the surfaces of the rocket very cold before launch, enough that ice forms on the surface, which then falls off during launch. | [
"The seal on the nozzle of the rocket is then released and rapid expulsion of water occurs at high speeds until the propellant has been used up and the air pressure inside the rocket drops to atmospheric pressure. There is a net force created on the rocket in accordance with Newton's third law. The expulsion of the... |
Is the European Union the first attempt to unify a whole continent peacefully ? | The broad answer is "probably yes" but it depends on how you define the question.
1. Is the EU a unification project? I think it is - and it's quite clear from the text of the Maastricht Treaty and the statements of politicians at the time of its signing - but it's definitely a disputed point (hard to cover the disput... | [
"The Heads of State or Government of the Member States of the European Communities meeting within the European Council resolved to continue the work begun on the basis of the Treaties of Paris and Rome and to create a united Europe, which is more than ever necessary in order to meet the dangers of the world situati... |
When did the sentiment, "That America was founded on Christian principles", begin to be popularized? | This is a great question! I will love to jump into it.
This notion that America was founded on as a Christian nation stems religious revivals that took America by storm during the first half of the 19th century. This period, often regarded as the "[Second Great Awakening](_URL_1_)" began in a period right after the C... | [
"Historians debate how influential Christianity was in the era of the American Revolution. Many of the founding fathers were active in a local church; some of them, such as Jefferson, Franklin, and Washington had Deist sentiments. Experts, researchers and authors have referred to the United States as a \"Protestant... |
Are stars visible in daylight? | It was Venus. Venus is bright enough to be seen in day light. Other planets and stars are too dim. Actually they are as bright during the day as they are during the night, but the sky is brighter so you can't see them. The brightness of the sky depends on atmosphere conditions. If you go high into the mountains, the sk... | [
"In some places (away from urban light pollution, moonlight, auroras, and other sources of light), where the sky is dark enough for nearly all astronomical observations, astronomers can easily make observations of point sources such as stars both during and after astronomical twilight in the evening and both before... |
what happens to particles when they dissolve? | If the solute is an ionic compound such as salt, then the crystalline lattice is broken up by the polar solvent (such as water) and each ion is held in the liquid by inter molecular hydrogen bonds.
So you are correct, the molecules split at the microscopic level.
If however, you are referring to, say, sugar, which i... | [
"Particle decay is the spontaneous process of one unstable subatomic particle transforming into multiple other particles. The particles created in this process (the \"final state\") must each be less massive than the original, although the total invariant mass of the system must be conserved. A particle is unstable... |
how is blood pressure measured? why do
doctors measure it? what does it tell them? | Blood pressure can be measured in many ways. Most commonly we use sphygmomanometers (you may know them as "blood pressure cuffs"). They wrap around your bicep to measure your radial pulse. On top of using the sphygmomanometer, we use a method called ausculatory method, which basically means inflating the sphygmomanome... | [
"Blood pressure generally refers to the arterial pressure in the systemic circulation. However, measurement of pressures in the venous system and the pulmonary vessels plays an important role in intensive care medicine but requires invasive measurement of pressure using a catheter.\n",
"For most patients, health ... |
Did homer's odysey exist by 700BC? | It depends what you mean by 'The Odyssey'.
There are several theories for how the poem was composed - one popular theory is ['oral composition'](_URL_0_); instead of being composed by an individual poet, advocates of this theory postulate that the story of the Odyssey would be recited by a poet with a unique compositi... | [
"Little is known about Heraclitus. It is generally accepted that he lived sometime around the 1st century AD. His one surviving work has variously been called \"Homeric Problems\", \"Homeric Questions\", or \"Homeric Allegories\".\n",
"In Homer's \"Odyssey\" (c. 8th century BC), upon Odysseus' return, his beloved... |
why is doing the paperwork for income called "paying taxes" when the taxes are already taken from our paychecks? | It's not called "paying taxes." It's called "filing a tax return." People are just sloppy when discussing some subject because you know what they mean. | [
"Income tax on wages is collected by means of a withholding tax system known as Pay-as-you-go (PAYG). For employees with only a single job, the level of taxation at the end of the year is close to the amount due, before deductions are applied. Discrepancies and deduction amounts are declared in the annual income ta... |
What are the names for the physical aspects of digital memory? | The RAM in your computer [is made of storage cells (one per bit): one transistor and one capacitor.](_URL_1_)
OTOH, Flash memory is made out of [NAND gates](_URL_0_), with one transistor (more precisely, a [floating-gate MOSFET](_URL_2_)) per bit in high-end SSDs, and one transistor for a couple bits in consumer hardw... | [
"Digital product memories (DPM) are a subclass of digital object memories, which include memories for all artifacts that were intentionally created such as containers and pieces of art or valuable and rare natural objects such as a marble plate or a lump of gold. Such objects don't have all the attributes of indust... |
Why did the US adopt 120v60hz as standard vs the much more widely used 220v50hz that most of the world uses? | The differences are mainly historical; however, the EU has mandated a standardization of mains at 230V, not 220V. The frequency difference was another historical engineering difference implemented at 60Hz based on Westinghouse generation standard and AEG Germany at 50Hz. US and Euro-based generating companies maintaine... | [
"A General Electric study concluded that 40 Hz would have been a good compromise between lighting, motor, and transmission needs, given the materials and equipment available in the first quarter of the 20th century. Several 40 Hz systems were built. The Lauffen-Frankfurt demonstration used 40 Hz to transmit power 1... |
how come when you stand up on a train you're completely still, but when you stand on a bus you have to hold on to something to stay upright? | Your body doesn't detect velocity, only change in velocity (acceleration). The reason that you get jostled around is due to a change in your velocity being resisted by your inertia.
Trains tend to move at a constant speed for a long time, typically, as they can go on long stretches of track. Since busses are on a shar... | [
"Low floors can be complemented by a hydraulic or pneumatic 'kneeling device', which can be used when the bus is not in motion, tilting it or lowering it at the front axle even further, often down to normal curb height. Depending on how close to the curb the bus is parked and wheelchair design, this can allow wheel... |
Quick question about dog genes | If we hadn't domesticated dogs, they would still be wolves. | [
"There are patterns of genes which are related by their function and these patterns can be found in both dogs and humans. This fact can be used to study the coevolution of gene function. Dogs accompanied humans when they first migrated into new environments. Both dogs and humans have adapted to different environmen... |
explain the evolutionary reason for having toes like i'm five. | It adds balance, and originally it was part of our use to hold things with our feet (They where basically like an extra set of hands before we started wearing sandals and whatnot). | [
"Humans usually have five toes on each foot. When more than five toes are present, this is known as polydactyly. Other variants may include syndactyly or arachnodactyly. Forefoot shape, including toe shape, exhibits significant variation among people; these differences can be measured and have been statistically co... |
Does the colour of coffee have any relation to how long it stays hot or it's temperature? | The coffee with two scoops will cool faster, and it has nothing to do with color.
Water has higher heat capacity than coffee, which means that the higher relative water content, the more heat it needs to lose for it to decrease in temperature.
_URL_0_ | [
"The most popular, but probably the least accurate, method of determining the degree of roast is to judge the bean's color by eye (the exception to this is using a spectrophotometer to measure the ground coffee reflectance under infrared light and comparing it to standards such as the Agtron scale). As the coffee a... |
why is cum white when fresh but clear at room temperature? | Real answer: there are enzymes in the semen that digest the fluid to set the sperm free. It goes from white to clear when the digestion is finished.
It turns out that semen isn't stored anywhere in the body. It's made on the spot when you orgasm by mixing the fluids of several different organs. The sperm cells are... | [
"Normal vaginal discharge is clear, white, or off-white. The consistency can range from milky to clumpy, and odor typically mild to non-existent. The majority of the discharge pools in the deepest portion of the vagina (the posterior fornix) and exits the body over the course of a day with the force of gravity. A t... |
how do voice recognition applications like siri know what we're saying? | First, it cuts the voice recording into really small segments, like 2/100 or 1/100 of a second long. Then, it multiplies each segment by a bell function to get a clear waveform in the middle with reduced interference from neighbouring samples. The waveform of each segment is analysed and compared to waveforms of known ... | [
"Voice Recognition is the ability to respond to verbal commands. Speech recognition refers to the capacity of the IA to convert voice entry into data. Both have been difficult to use in many construction applications due to ambient noise, construction jargon which varies by region, trade, and company, and because o... |
Is the sweat produced by exercising different from the sweat produced by sedentary activities e.g. sweating after a shower or sweating in a hot car? | Hello and welcome to AskScience. Please don't guess the answer.
It would be useful to find a peer reviewed source that talks about the composition of sweat, and the variation in composition that is possible. | [
"In humans, sweating is primarily a means of thermoregulation, which is achieved by the water-rich secretion of the eccrine glands. Maximum sweat rates of an adult can be up to 2–4 liters per hour or 10–14 liters per day (10–15 g/min·m), but is less in children prior to puberty. Evaporation of sweat from the skin s... |
Did the Romans ever use olive oil to fry food? | Yes, the cookbook *On Culinary Matters* by Apicius makes frequent reference to frying in oil. You can read it [here](_URL_0_) with pretty copious notes, which are very neccesary given how vague it tends to be.
This isn't a particularly in depth answer, so I am happy to answer any follow ups. | [
"Although olives were used to produce oil from the Bronze Age, it was only by the Roman period that the techniques were introduced to cure olives in lye and then brine to remove their natural bitterness and make them edible as a food.\n",
"Olive oil was fundamental not only to cooking, but to the Roman way of lif... |
why are some decisions voted on by the people and others just by politicians? | You have probably heard that the US is a Democratic Republic. This roughly breaks down to mean, that everyone gets to vote (democratic) for representatives who decide laws (republic).
So in the ideal system, you vote for your representative, congressman or senator, and they vote on all issues for you.
The idea is th... | [
"This does not mean that voters make poor and biased decisions: rather that in carrying out their everyday responsibilities (like working and taking care of a family), many people do not have the time to devote to researching every aspect of a candidate's policies. So many people find themselves making rational dec... |
Why were the designs for nuclear weapons declassified? | The answer to this could be quite long, because there are multiple levels of information in question. Here's a summary of the basic concepts (I can elaborate on any of these at length):
* The very basic idea of the gun-type weapon was first released in the Smyth Report (1945), only a few days after the bombing of Naga... | [
"BULLET::::- US Department of Energy document RDD-8, \"Restricted Data Declassification Decisions - 1946 to the Present\", the official account of which nuclear weapons design information has been or should be declassified and placed in the public domain.\n",
"US nuclear weapons of all types – bombs, warheads, sh... |
why can't tyres be recycled into more tyres? i always see tyre graveyards where they are just left to rot or they are burned. | They can be recycled. You can convert them back into a more suitable base synthetic rubber that you can use for a variety of things like more tires. The problem is that this is a generally prohibitively expensive thing to do -- it's cheaper just to make new tires.
Tires are also combustable, which means they can and a... | [
"Tire recycling or rubber recycling is the process of recycling vehicles tyres that are no longer suitable for use on vehicles. These tyres are among the largest and most problematic sources of waste, due to the large volume produced and their durability. Those same characteristics which make waste tyres such a pro... |
why is the portuguese man o' war and other siphonophore considered to be a colony of different organisms if they all have the same dna? wouldn't zooids just be concidered organs? | Its like bacteria that can reproduce asexually by splitting themselves. The 2 new bacteria are seperate, but share their dna.
Similarly, it can br thought of like cloning. If you clone a person, they will be 2 seperate people, but share the same dna.
So it is a city of clones that beocme specialized to do certain t... | [
"There are many endemic insect species, most only found in certain parts of Portugal, while other species are more widespread like the stag beetle (\"Lucanus cervus\") and the cicada. The Macaronesian islands (Azores and Madeira) have many endemic species (like birds, reptiles, bats, insects, snails and slugs) that... |
Why wasn't the German Empire partitioned like the Austro-Hungarians after WW1? | Germany was ethnically and religiously more unified. Germans were generally Catholic, Protestant, or Jewish and all of these people spoke German as their primary language, or Yiddish, which is partly based in German (and whose speakers were generally bilingual). This population thought of itself as German, though muc... | [
"The Russian, German, and Austro-Hungarian empires collapsed at the end of World War I, and were replaced by republics. Finland, Estonia, Latvia, Lithuania, Poland, and Czechoslovakia became independent countries. Yugoslavia and Romania expanded into former Austro-Hungarian territory. The Soviet Union succeeded the... |
difference between probiotics and prebiotics | Prebiotics are essentially food for probiotics. The way they work is that the probiotics, which boost immunity and general health, mainly for the GI. The probiotics feed on the prebiotics, so they will be able to do what I listed above better.
[Source](_URL_0_) in case I missed anything | [
"Probiotics are products aimed at delivering living, potentially beneficial, bacterial cells to the gut ecosystem of humans and other animals, whereas prebiotics are indigestible carbohydrates delivered in food to the large bowel to provide fermentable substrates for selected bacteria. Strains of LAB are the most c... |
Can people with lazy eye choose which eye to use and alternate between them? | Optometrist here. The answer is "sometimes," and "it depends."
"Lazy eye" means many different things to different people. The clinical definition of lazy eye, or "amblyopia" is an eye with reduced vision not due to any organic cause. Basically it is a healthy eye, but due to hindered development, does not see well, e... | [
"Strabismus, sometimes also incorrectly called lazy eye, is a condition in which the eyes are misaligned. Strabismus usually results in normal vision in the preferred sighting (or \"fellow\") eye (the eye that the person prefers to use), but may cause abnormal vision in the deviating or strabismic eye due to the di... |
Did traditional pike and shot armies ever fight all infantry or all cavalry armies in the open field? | > native American force
Neither the Spanish nor other European powers ever sent an army to the Americas in the initial stages of conquest.
> Mongol horse archer army
No.
> Did traditional pike and shot armies ever fight all infantry or all cavalry armies in the open field?
The closest was probably during t... | [
"It was not uncommon for aggressive pike formations to be composed of dismounted men-at-arms, as at the Battle of Sempach (1386), where the dismounted Austrian vanguard, using their lances as pikes, had some initial success against their predominantly halberd-equipped Swiss adversaries. Dismounted Italian men-at-ar... |
Astrophysics: Is there a practical reason to build a particle accelerator in space? | not really astronomy, but building in weightlessness confers the advantage that the components aren't limited by their own weight. If you've seen pictures of the LHC as it was being built you can see huge support structures for the various parts. Being in low-gravity makes the engineering much simpler and thus we can b... | [
"The field of astroparticle physics is evolved out of optical astronomy. With the growth of detector technology came the more mature astrophysics, which involved multiple physics subtopics, such as mechanics, electrodynamics, thermodynamics, plasma physics, nuclear physics, relativity, and particle physics. Particl... |
why is uganda so anti gay? | It's cultural. They seeme to be very conservative, probably to the point of making Tea Partiers look like bleeding heart liberals. They don't seem to be "anti-Western" in the sense that they are doing it to rebel against Western pressure. | [
"Uganda has a history of anti-gay laws that date back to its colonization by the British Empire. The Penal Codes of 1950, enacted by the ruling British government, contained sodomy laws that are still in force today. However, recent, intensifiying anti-homosexual sentiment in Uganda has been associated with the dis... |
Nutritionally speaking, is the crust really the best part of bread or were my parents lying to me throughout my childhood? | Amino acids are consumed during the Maillard reactions that brown the crust of your bread, and the resulting reaction products are not nutritionally relevant. So strictly speaking, the crust is less nutritious than the crumb. | [
"Bread crust is formed from surface dough during the cooking process. It is hardened and browned through the Maillard reaction using the sugars and amino acids and the intense heat at the bread surface. The crust of most breads is harder, and more complexly and intensely flavored, than the rest. Old wives tales sug... |
how to properly do laundry. | OK, most posts are helpful but IMHO not complete.
You need a washing machine and knowledge of 2 main settings:
* The first is a low temperature wash used for colours and delicate items. This is normally around 30-40 degree Celsius (about 100 Fahrenheit).
* The second is a high temperature wash used for white ite... | [
"Laundry refers to the washing of clothing and other textiles. Laundry processes are often done in a room reserved for that purpose; in an individual home this is referred to as a laundry room, Laundry in Australian English or utility room. An apartment building or student hall of residence may have a shared laundr... |
if a pilot crashes a plane due to a mechanical failure and crash lands into some number of people, killing them, who is at fault? | Well, 'mechanical failure' excludes the pilot entirely.
Now, it's up to the National Transportation Safety Board. (NTSB) or equivalent agencies to investigate and determine whether it's the maintenance (airlines, military branch, or private operator) at fault, or the manufacturer (who built the plane(Boeing, Lockheed,... | [
"Accidents where the aircraft is out of control at the time of impact, because of mechanical failure or pilot error, are not considered CFIT (they are known as \"uncontrolled flight into terrain\"), nor are incidents resulting from the deliberate action of the person at the controls, such as acts of terrorism or su... |
How does an Analog-to-Digital converter work ? | There's more than one type of ADC. Common types are SAR, flash, and delta-sigma.
A SAR ADC (essentially) ramps up a voltage using a binary counter until the voltage exceeds the sample voltage. Imagine turning up a dial, then reading the dial when a light comes on and reporting the value. SAR stands for Successive Appr... | [
"In electronics, a digital-to-analog converter (DAC, D/A, D2A, or D-to-A) is a system that converts a digital signal into an analog signal. An analog-to-digital converter (ADC) performs the reverse function.\n",
"In electronics, a digital-to-analog converter (DAC or D-to-A) is a circuit for converting a digital s... |
why do some people walk on their tippy-toes? | Personally, because I grew up in and live in a house with raised timber floors. Clumping through it with a heel-toe walking style makes too much noise and would shake things off shelves. | [
"Toe walking refers to a condition where a person walks on their toes without putting much weight on the heel or any other part of the foot. Toe walking in toddlers is common. These children usually adopt a normal walking pattern as they grow older. If a child continues to walk on their toes past the age of three, ... |
Is there a beginning of time? | We are not exactly sure when our idea of time began but the common theory is that time began when the Big Bang happened. Therefore you could consider the beginning of time to be the creation of the universe.
[From the time wiki:](_URL_0_)
> Stephen Hawking in particular has addressed a connection between time and th... | [
"The end time (also called end times, end of time, end of days, last days, final days, doomsday, or eschaton) is a future time-period described variously in the eschatologies of several world religions (both Abrahamic and non-Abrahamic), which teach that world events will reach a final climax.\n",
"The End of Tim... |
I saw earlier in /r/todayilearned that there's a giant space cloud composed of water vapor. Is it possible that this will eventually form planets made exclusively of water? | [This paper](_URL_0_) (pdf) by Leger et al. covers most aspects of what a possible ocean planet might be like, including a section on the internal structure. I'm sure I've seen a more detailed paper that covers ice planet structures for a variety of different cases, which had some interesting bits on different types o... | [
"Water vapor has also been confirmed outside the Solar System. Spectroscopic analysis of HD 209458 b, an extrasolar planet in the constellation Pegasus, provides the first evidence of atmospheric water vapor beyond the Solar System. A star called CW Leonis was found to have a ring of vast quantities of water vapor ... |
how do workers build buildings and structures without holding any manuals or instructions? | Construction is very specialized. Usually the person who does the layout is not the same person doing the physical work. On my project, for instance, there is a primary construction guy who basically makes X marks on the ground to denote where certain column type structures need to go (using the plans), and then an e... | [
"Engineering technicians help solve technical problems in many ways. They build or set up equipment, conduct experiments, and collect data and calculate results. They might also help to make a model of new equipment. Some technicians work in quality control, where they check products, do tests, and collect data. In... |
advanced math | P=NP is theoretical computer science, which is technically math but not usually considered as such.
Hot topics in pure math right now are:
**WARNING THE FOLLOWING IS NOT ELI5 AT ALL**
* [algebraic geometry](_URL_6_): the study of shapes [locally] defined by a system of polynomial equations. Classically, algebraic ge... | [
"Advances in Mathematics is a mathematics journal publishing research on pure mathematics. It was founded in 1961 by Gian-Carlo Rota. The journal currently publishes 18 issues each year, in three volumes.\n",
"Mathematical maturity is an informal term used by mathematicians to refer to a mixture of mathematical e... |
melting glass | Your physics teacher is WRONG. People used to believe glass was a liquid but in fact that is a myth caused by medieval windows deforming over time.
Check out this article for more info: _URL_0_ | [
"glass is melted and formed by typical glassworking techniques into the desired shape. This is heat-treated, which causes the material to separate into two intermingled \"phases\" with distinct chemical compositions. One phase is rich in alkali and boric oxide and can be easily dissolved in acid. The other phase is... |
does ac electricity work and why/how does the current shift direction? | Imagine a circuit with a battery powering a lightbulb. The electrons flow from one end of the battery around the circuit to the lightbulb and back to the battery. Now if you flip the battery so that the electrons flow the other way the lightbulb isn't going to care and will still light up. Alternating current is basica... | [
"In one simple inverter circuit, DC power is connected to a transformer through the center tap of the primary winding. A switch is rapidly switched back and forth to allow current to flow back to the DC source following two alternate paths through one end of the primary winding and then the other. The alternation o... |
What's the biggest living form ? | It depends on where you draw the line for what a single "organism" is.
I believe the largest organism on record that is generally accepted as a single unit is a [mushroom colony found in Oregon](_URL_0_) that spanned a couple thousand acres and weighed over 600 tons.
The Wikipedia page gives you a good idea of the ... | [
"Certain extinct cephalopods rivalled or even exceeded the size of the largest living species (Carnall, 2017). In particular, the subclass Ammonoidea is known to have included a considerable number of species that may be considered \"giant\" (defined by Stevens, 1988 as those exceeding in shell diameter). The large... |
What civilisation existed before Sumer? I know a little bit about Jericho & Cathalhoyuk, but I’m not too sure about anything else & can’t find too much around the internet | **Sumer is the first "civilization."**
Archaeologists have used many definitions of "civilization" over the years, but today most use it to mean urbanized, state-level societies.
A "civilization" has *all* of the following: (1) cities, with large, complex social organizations, themselves in much larger territories th... | [
"Jericho is believed to be one of the oldest continuously inhabited cities in the world, with evidence of settlement dating back to 9000 BCE, providing important information about early human habitation in the Near East. Along the Jericho–Dead Sea–Bir es-Saba–Gaza–Sinai route, a culture originating in Syria, marked... |
the shape of mushroom clouds | The initial explosion is so intense and hot it pushes and burns the air around it out, when the energy dissipates it essentially creates a negative pressure zone. The rush of air back to the center point is moving very fast, when it collides with the dusty air from the other circular directions it rises, hence the mush... | [
"Mushroom clouds result from the sudden formation of a large volume of lower-density gases at any altitude, causing a Rayleigh–Taylor instability. The buoyant mass of gas rises rapidly, resulting in turbulent vortices curling downward around its edges, forming a temporary vortex ring that draws up a central column,... |
Why is it that water tastes differently when it comes out of the faucet slowly vs. quickly? | I am no expert. I think that might be because the water has air in it when it comes out faster. If you look at it while coming out faster, you can see how it's not a steady stream, but it has air throughout. The change in taste probably comes from the amount of sediment in the water (more air = more sediment).
On a si... | [
"Because the aerator limits the water flow through the faucet, water use is reduced as compared to the same time of flow without an aerator. In the case of hot water, because less water is used, less heat energy is used.\n",
"Another common problem occurs when the incoming water is too warm and is less effective ... |
why do iphones and louis vuitton bags' prices are standard all over the world yet medicine prices vary extremely worldwide? | Because drugs are very heavily regulated relative to consumer products. | [
"Some prescription medications, most notably popular and branded drugs, can have very high prices in comparison to their cost of transport. In addition, pharmaceutical prices can vary significantly between countries, particularly as a result of government intervention in prices. As a consequence, the grey market fo... |
what 'diminishing returns' means in a gym sense | There is a hard limit to the amount of muscle you can gain with every passing year. When you first start, you will get a fairly good amount but this will diminsh every year from then on if you keep lifting without a long break. After a while, the amount will be quite negligble. This all applies when your are a natural ... | [
"Rebound exercise begins as soon as someone steps on a rebounder and begins to move their body. It can be highly aerobic — full-on sprints and interval training are ideal on a rebounder, because it does not jar the physical body anywhere near as much as does hard ground — or it can be very slow and gentle, with onl... |
How were one or more miscarriages viewed in the late middle ages? | From my source (Cunningham's *Children and Childhood in Western Society Since 1500*) it is implied that there was grief for children. Not much is mentioned when it comes to miscarriages. But people did show a lot of concern when a child the first seven years of a human's life, *infantia*, died. Especially if the child ... | [
"In medieval western Europe, any efforts to halt or prevent pregnancy were deemed immoral by the Catholic Church. Women of the time still used a number of birth control measures such as coitus interruptus, inserting lily root and rue into the vagina, and infanticide after birth.\n",
"Society's reactions to miscar... |
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