question stringlengths 3 301 | answer stringlengths 9 26.1k | context list |
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why does the human body become dependant on drugs that are not natural to it? | It depends a lot on the drug as to what's happening in the body, but two general reactions is that the drug either induces a standard process in the body, or replaces a hormone in the body. In either case, the body learns to stop inducing or producing whatever process the drug supplements because it saves the body ene... | [
"Drugs (especially opioids and stimulants) can change the motivational patterns of a person and lead to desocialization and degradation of personality. Acquisition of the drugs some times involves black market activities and leads to criminal social circle.\n",
"Why do humans seek out and at times even develop ad... |
The Eagle Nebula - what would it currently look like? | Unless this is *very* recent news (i.e., the last day or so), then I don't think it's true. There hasn't been a supernova in the Milky Way for some time -- [they average at just a couple per century](_URL_0_) -- which is an interesting problem in itself.
You should be fine using the HST image. | [
"The Eagle Nebula (catalogued as Messier 16 or M16, and as NGC 6611, and also known as the Star Queen Nebula and The Spire) is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Chéseaux in 1745–46. Both the \"Eagle\" and the \"Star Queen\" refer to visual impressions of the ... |
why is southern europe relatively lush compared to the deserts of north africa when they are both next to the mediterranean? | Okay, so the comments so far only are only partially correct but the main reason is persistent high pressure which results in subsidence. There is a concept referred to as a [Hadley cell](_URL_0_) which is a basic description of how the atmosphere circulates. Essentially, the equator is hot and the poles are cold. Hot ... | [
"In Europe, some Mediterranean areas have a steppe-like vegetation, such as central Sicily in Italy, southern Portugal, parts of Greece in the southern Athens area, and central-eastern Spain, especially the southeastern coast (around Murcia), and places cut off from adequate moisture due to rain shadow effects such... |
I've heard that the Ancient Romans saw large penises as a sign of barbarism. To what extent is this the case? | In general, the surviving sculptures, vases, and writings describing male beauty in the Greco-Roman world depict the ideal of beauty for men (especially young men) as being hairless, thin, athletic, and with a small penis with a tapering foreskin. Large penises are most often found on satyrs, ugly old men, and barbaria... | [
"Nonetheless, there are indications that the Greeks had an open mind about large penises. A statue of the god Hermes with an exaggerated penis stood outside the main gate of Athens and in Alexandria in 275 BC, a procession in honor of Dionysus hauled a 180-foot phallus through the city and people venerated it by si... |
why does my dog smell differently when he comes inside from the cold? | The air oxidizes the oils in his fur, changing the way it smells to us. It happens to people too. Try smelling yourself before and after you spend some time in a windy area. | [
"Dogs, as with all mammals, have natural odors. Natural dog odor can be unpleasant to dog owners especially when dogs are kept inside the home, as some people are not used to being exposed to the natural odor of a non-human species living in proximity to them. Dogs may also develop unnatural odors as a result of sk... |
What causes black holes to have an upper limit to their rotational speed? | The *intuitive* reason is that angular momentum has an associated rotational energy. This energy increases the mass of the black hole (through E = Mc^(2)).
Now, if you fix the total mass M, increasing the spin J then increases the fraction of M that is due to this rotational energy, and decreases the fraction of "norm... | [
"In this way, rotational energy is extracted from the black hole, resulting in the black hole being spun down to a lower rotational speed. The maximum amount of energy is extracted if the split occurs just outside the event horizon and if particle C is counter-rotating to the greatest extent possible.\n",
"A rota... |
How did arabic women dress during the abbasid caliphate? | The actual cultural dress? No idea. But they were definitely not dressed like belly dancers. The average Muslim woman would have covered the majority of her body other than her face, hands, and feet. Muslim males would have covered the same area except for manual laborers who might have taken their shirt off while work... | [
"Muslim Turkish-Cypriot women wore traditional Islamic headscarves. When leaving their homes, Muslim Cypriot women would cover their faces by pulling a corner of the headscarf across their nose and mouth, a custom recorded as early as 1769.\n",
"In contrast to the earlier era of the Prophet Muhammad and the Rashi... |
how can humans survive a partial beheading? | If that spinal cord isn’t cut, you won’t die instantly. Granted, you won’t live long with a severed carotid without immediate medical attention (even then it’s a crap shoot). | [
"Immurement (from Latin \"im-\" \"in\" and \"murus\" \"wall\"; literally \"walling in\") is a form of imprisonment, usually for life, in which a person is placed within an enclosed space with no exits. This includes instances where people have been enclosed in extremely tight confinement, such as within a coffin. W... |
What are the differences between a mole and a freckle? | Both are types of what are known as *melanocytic lesions* - basically areas with a greater amount of production of melanin than the rest of the skin. Melanin is the pigment that is responsible for difference in skin tone and also the colour of moles and freckles.
Melanin is produced by cells called *melanocytes*. The ... | [
"Mole-Stache (a play on mole and moustache) is an orange mole-like alien with a British accent and a yellow moustache that can be used in a variety of ways that include serving as an extra set of hands or as a makeshift propeller. While Molestache first appeared in \"Outbreak\" while Blukic and Driba were trying to... |
Do any wild organisms have a symbiotic relationship with another to babysit their young? | There are functional relationships where one species invests itself in raising the young of another, although the examples I'm familiar with are completely one-sided, which makes them parasitic and not symbiotic. Consider for instance the cuckoo, which will lay its eggs in another birds nest and just ... leave. The oth... | [
"Most sexually reproducing animals spend their lives as diploid, with the haploid stage reduced to single-cell gametes. The gametes of animals have male and female forms—spermatozoa and egg cells. These gametes combine to form embryos which develop into a new organism.\n",
"Exposed eggs are typically and readily ... |
Can a wave's wavelength be smaller than Planck length? And why? | No one knows the answer to this question.
The Planck length just represents the scale at which our current models break down, the scale at which a theory that combines gravity and quantum mechanics will be needed. What the new models that work at that scale will tell us about physics at that scale or smaller is an op... | [
"Whether objects heavier than the Planck mass (about the weight of a large bacterium) have a de Broglie wavelength is theoretically unclear and experimentally unreachable; above the Planck mass a particle's Compton wavelength would be smaller than the Planck length and its own Schwarzschild radius, a scale at which... |
if companies like samsung and apple pay (m/b)illions in "patent wars" about violating design patents, how can companies easily create identical iphone or samsung device knockoffs commonly seen on ebay and amazon? | They aren't in serious competition, for one; those are entirely different price points.
Also, China. | [
"A \"patent war\" between Samsung and Apple started when the latter claimed that the original Galaxy S Android phone copied the interfaceand possibly the hardwareof Apple's iOS for the iPhone 3GS. There was also smartphone patents licensing and litigation involving Sony Mobile, Google, Apple Inc., Samsung, Microsof... |
How would people get phone messages during the 1930's? | Not a silly question. There were two types of calls that could be made during this time: person-to-person and station-to-station. If you had a specific person you wanted to talk to you would request a person-to-person call. You wouldn't be billed for the long distance charges until that person came to the phone. This w... | [
"In the call-box system developed in 1872, a customer would ring the telegraph office for a messenger who would then speed to the customer's door to pick up a handwritten message and return to the telegraph office to have it sent electrically to its destination.\n",
"The Second World War made military use of radi... |
Why is the weight of a molecule in atomic mass units not exactly equal to the sum of the protons and neutrons? | /u/RobusEtCeleritas has a good explanation. It is also important to know that the masses of atoms are measured in amu (atmic mass units), where 1 amu is 1/12 the mass of a carbon 12 atom. This takes into account some of the binding energy that was brought up, but not every atom has the same binding energy per nucleon (... | [
"The sum of the atomic number \"Z\" and the number of neutrons, \"N\", gives the mass number \"A\" of an atom. Since protons and neutrons have approximately the same mass (and the mass of the electrons is negligible for many purposes) and the mass defect of nucleon binding is always small compared to the nucleon ma... |
What race was Attila? | Do you mean what race *would* be Attila today? Race as we know it today is an early modern construct that wouldn't have played the same role in his life, akin to saying was he a Christian or a Muslim. | [
"Attila (; fl. c. 406–453), frequently called Attila the Hun, was the ruler of the Huns from 434 until his death in March 453. He was also the leader of a tribal empire consisting of Huns, Ostrogoths, and Alans among others, in Central and Eastern Europe.\n",
"Attila grew up in a rapidly changing world. His peopl... |
why are canker sores, ingrown toenails, and splinters so excrutiatingly painful? | Hands, feet, the face, the mouth and the external genitals have a very large number of nerve endings that give a high level of the sense of touch in those parts. Other parts of the body are a lot less sensitive. Some internal organs sense no physical pain at all. It's pretty easy to see why the body has evolved this wa... | [
"They tend to be painful due to the pressure applied to the nail bed and plate. They can involve destruction of the nail bed. These lesions are not true osteochondromas, rather it is a reactive cartilage metaplasia. The reason it occurs on the dorsal aspect is because the periosteum is loose dorsally but very tight... |
What is the reason for China's relatively modest nuclear arsenal? Why is China the only nuclear weapons state to have given an unqualified security assurance to non-nuclear-weapon states? | Under the theory of nuclear deterrence, most nuclear weapons states have little reason to build beyond that quantity of warheads. It's enough to effectively destroy any country. That's one reason why most nuclear weapons states stop near the 300 mark. The US and Russia are the exception because of their massive arms ra... | [
"In 2004, China stated that \"among the nuclear-weapon states, China ... possesses the smallest nuclear arsenal,\" implying China has fewer than the United Kingdom's 200 nuclear weapons. Several non-official sources estimate that China has around 400 nuclear warheads. However, U.S. intelligence estimates suggest a ... |
monte carlo simulation and markov chain or more specifically the setting up of the data. | > BUT if you have a - day, theres a i dunno + 10% bonus that it will be a - day tomorrow too.
Then it isn't a Markov chain. A Markov chain's defining property is that the future evolution of the system depends *only* on its current state - it is "memoryless". You could still do a Monte Carlo simulation, since those... | [
"Monte Carlo simulation provides the capability, through sensitivity analysis, to identify single or chains of events. These chains of events can be identified by analyzing the correlations between the main project parameters, such as project duration or cost, and the event chains. These are called “critical events... |
What is the significance in electric and magnetic components of EM radiation being right angles to one another? | The components of the electric and magnetic fields are different in different inertial reference frames.
But they can be written in terms of an object called the [electromagnetic field tensor](_URL_0_), which is relatively straightforward to transform between frames.
From this tensor you can construct two invariant q... | [
"Both of these EMFs, despite their apparently distinct origins, are described by the same equation, namely, the EMF is the rate of change of magnetic flux through the wire. (This is Faraday's law of induction, see below.) Einstein's special theory of relativity was partially motivated by the desire to better unders... |
Is riding a bike muscle memory? | **Edit, Source:** [I am on a course to acquire one of these in Physical Education.](_URL_0_) ~~There's no way to compare it to American qualifications, so I wouldn't bother trying if I were you.~~
> If there's a corresponding track, it would have to be closer to [Advanced Placement](_URL_2_) level courses offered in... | [
"Muscle memory is a form of procedural memory that involves consolidating a specific motor task into memory through repetition, which has been used synonymously with motor learning. When a movement is repeated over time, a long-term muscle memory is created for that task, eventually allowing it to be performed with... |
what it that feeling of horrible burning when water goes up your nose when diving into a pool or just taking a shower and reaching down for something? |
The main reason why water burns when it goes up your nose is because the salinity of the water does not match the salinity of the cells in your body. The salinity of freshwater is much lower than your body, so when water gets into your nose and into your sinuses, some of the cells that line the sinus and nasal cavitie... | [
"Some warning signs that occur include pain, burning and numbness at the place of infection. Also people with the disease experience sleeplessness, headaches, irritability, difficulty swallowing and throat spasms. They may experience fear of water (hydrophobia).\n",
"Erythema ab igne (EAI), also known as hot wate... |
What are the pros and cons of HDL, LDL, and omega-3 fatty acids? (Also what are omega-3 fatty acids?) | Hi there.
After digestion, your lipids are packed into droplets known as chylomicrons. From there, they are transported to the liver and re-packaged as lipoproteins (containing cholesterol, triglycerides, fatty acid etc).
So as these lipoproteins, fresh from the liver, transport fatty acids, cholesterol and trigl... | [
"Omega-3 fatty acids are polyunsaturated fatty acids (PUFAs) that are essential for proper brain and cognitive development. They also play a large role in the production of anti-inflammatory eicosanoids, which has been shown to reduce the risk of cardiovascular disease and other inflammatory diseases. There are thr... |
how does the air stay so hot in the nighttime when the sun isn’t even out? and how is it that the sun makes the temperature only like 5-10 degrees warmer during the daytime in the summer? | The same reason the inside of an oven doesn't return to room temperature the instant you turn it off. Both the atmosphere and the ground absorb heat during the daytime. It takes time for this heat to dissipate after the sun sets. Furthermore, and this answers some of the second part of your question as well, air doesn'... | [
"BULLET::::- Due to the thin atmosphere, the temperature difference between day and night is much larger than on Earth, typically around 70 °C (125 °F). However, the day/night temperature variation is much lower during dust storms when very little light gets through to the surface even during the day, and instead w... |
When does a comet stop moving? | You can think of a comet entering our solar system as a ball rolling down a hill. As it gets closer and closer to the sun, it'll speed up more and more. When it heads away from the sun, it'll be slowing down, like a ball going uphill. This is because of the effect of the sun's gravity. It won't otherwise come to a stop... | [
"Each time a comet swings by the Sun in its orbit, some of its ice vaporizes and a certain amount of meteoroids will be shed. The meteoroids spread out along the entire orbit of the comet to form a meteoroid stream, also known as a \"dust trail\" (as opposed to a comet's \"gas tail\" caused by the very small partic... |
why is it racist to do an asian accent but not racist to to a british or an australian etc. one | If you are a white American, it is because that is the same race. Brits and Australians speak the same language as you, just with different accents. An Asian has learned your language even though it is not their native tongue, and you would be mocking them. | [
"In response to the issue, Bollywood star Amitabh Bachchan turned down an honorary doctorate from the Queensland University of Technology. Fellow Indian actor, Aamir Khan, has condemned the attacks, stating that, \"[It is] most disturbing to hear about racist attacks on Indians living in Australia. Quite a shame. W... |
why are so many of the world's greatest classic rock bands from england? what were the influences at that time and when did their rising popularity start to decline? | Two reasons.
1. The Beatles. They were HUGE, and seemingly came from nowhere. They became the most popular band in history, and inspired many small time bands and musicians in England to try and go big as well.
2. Empire. GB used to basically rule the world, and a lot of the world took up parts of British culture bec... | [
"At the same time, rock and roll was played in Britain after 1955. The British product has generally been considered less successful than the American version of the genre at the time, and made very little international or lasting impact. However, it was important in establishing British youth and popular music cul... |
Does the pull of gravity increase or decrease as you approach the center of a mass? | I assume when you say "approach the CoM", you mean drilling a borehole.
The [Shell Theorem](_URL_0_) states that it decreases. Assuming the body in question is radially uniform, the gravity at a point inside the body is equal to the gravity pull as if the mass above you (i.e. the "shell" of earth above you) didn't exi... | [
"The acceleration due to gravity depends on the gravity of the mass, which rests inside of the object. The gravity decreases at longer distance between centers of mass. The acceleration due to gravity furthermore is influenced by the rotation of the earth. As centrifugal force increases at longer earth's axis dista... |
how has the previous generation “ruined the housing market” for millennials? | The short answer, we don’t make as much money as they did.
Slightly longer answer: US household median income in 1970 was $9,780 which has a buying power of $64,700 in today’s money. The current median US wage is 61,800, about $3,000 less or effectively 5% less money available per year than they did.
Next, median home ... | [
"The number of multigenerational households has been steadily rising because of the economic hardships people are experiencing today. According to the AARP, multigenerational households have increased from 5 million in 2000 to 6.2 million in 2008.\"There's no question that with some ethnicities that are growing in ... |
why is it important to create credit and the benefits of it | Essentially, "building credit" is just showing that if you borrow someone else's money, they can trust you to pay it back. If I'm a random stranger, you probably wouldn't want to lend me a bunch of money, but if a bunch of people you trust all vouch for me that they loaned me money and I paid them back in full and on ... | [
"Credit allows a borrower to increase today’s standard of living at the expense of some future standard of living. Thus in financial terms, credit allows a consumer to spend a large amount of money today (raising their standard of living) while reducing their disposable income as the debt is repaid (lowering their ... |
how i shock people/get shocked by touching things? (i.e. static electricity) | > How does it get built up?
Everything is made of charges of positive electricity and negative. The two kinds of electricity are carried by the protons and electrons of atoms. But usually an object is electrically "neutral," because its own pos and neg charges are equal in number and cancelled out.
"Static electr... | [
"The feeling of an electric shock is caused by the stimulation of nerves as the neutralizing current flows through the human body. The energy stored as static electricity on an object varies depending on the size of the object and its capacitance, the voltage to which it is charged, and the dielectric constant of t... |
if someone started wearing weights/ weighted clothing, increasing as they got used to it, what would the effects actually be if they went through having it on often? | You will destroy your joints, your body is not Designed to have weight on the ends of your limbs and why we gain weight on our butts and bellies. Also the weights tend to flap around a bit when you move pulling in directions you don't want.
Pretty sure there is a 'because science' YouTube video on this topic if your ... | [
"In those who are overweight or obese, a 2016 study indicates that the use of wearable technology combined with standard behavioral interventions results in less rather than more weight loss after two years of use when compared to usual weight loss interventions. There was no evidence that the devices altered the a... |
how can large chains (target, walmart, etc) produce store brand versions of nearly every product imaginable while industry manufacturers only really produce a single type of item? | Because they don't actually make it.
Costco doesn't make "Coscto Whisky" Costco has a contract with (it's not but for ease of names) Jack Daniels. And again for ease I will use "Bottles" not "Barrels"
If Jack Daniels sells their whisky for $20 a bottle, say it costs them $10 to produce. Costco says "We want to buy yo... | [
"Retailers, like Walmart and Target, buy the product from the manufacturer and sell them directly to the consumer. This channel works best for manufacturers that produce shopping goods like, clothes, shoes, furniture, tableware, and toys. Since consumers need more time with these items before they decide to purchas... |
why are toilets round? | Your ass is round. | [
"Chutes are in common use in tall buildings to allow the rapid transport of items from the upper floors to a central location on one of the lower floors or basement. Chutes may be round, square or rectangular at the top and/or the bottom.\n",
"Squircles have also been used to construct dinner plates. A squircular... |
how did other languages adopt the latin alphabet? | Did a little search and found this, might interest you
_URL_0_
Seems that a major factor is the spread of Western Christianity and the roman empire. | [
"The Latin alphabet spread from Italy, along with the Latin language, to the lands surrounding the Mediterranean Sea with the expansion of the Roman Empire. The eastern half of the Roman Empire, including Greece, Asia Minor, the Levant, and Egypt, continued to use Greek as a lingua franca, but Latin was widely spok... |
what made concorde so fast compared to other commercial planes? | It was built to go that fast. The market isn't really willing to deal with the costs and complications of a plane like as compared to 747s and other craft we'd now call conventional though, so the concorde failed.
It's just like how someone can build ships that go far faster than your average freighter, but the averag... | [
"Within its own category in commercial aviation, the supersonic airliner Concorde began service in 1976. Its four Rolls Royce/Snecma Olympus 593 turbojets allowed it to cruise at twice the speed of sound. At the time of inception it was regarded as the future of air transportation. However, in large part due to hig... |
Is it possible to make 100% pure alcohol? | One thing to consider is the definition of purity, and the fact that it's essentially impossible for any macroscopic sample of a substance to be 100% pure at room temperature.
I can confidently say that nobody has ever made a bottle of ethanol that contains no other molecule. We probably haven't even made a bottle ... | [
"However alcoholic drinks cannot be further purified to 0.00% alcohol by volume by distillation. In fact, most drinks labeled non-alcoholic contain 0.5% ABV as it is more profitable than distilling it to 0.05% ABV often found in products sold by companies specializing in non-alcoholic drinks.\n",
"Alcohol of more... |
how would alien races communicate via mathematics? | You could do this using a series of pulses from an electromagnetic beam.
Let's say you send out a group of 5 pulses. After a pause, you send out 7 more. After another pause, you send out 12.
It doesn't matter what language the aliens speak and it doesn't matter what base their number system is expressed in or what sy... | [
"The problem of alien language has confronted generations of science fiction writers; some have created fictional languages for their characters to use, while others have circumvented the problem through translation devices or other fantastic technology. For example, the Star Trek universe makes use of a 'universal... |
I stumbled across an image of the inside of the Hagia Sophia, it appears Christian imagery was not removed by the ottomans, why was this? | These mosaics were painted over but not removed when the city was taken by Mehmed II. Minarets, minbar, and mihrab were added and it became a functional mosque. After the fall of the empire and the transformation of the Hagia Sophia from mosque into museum in the 1920s, restorationists removed some of the plaster and w... | [
"Hagia Sophia (from the , \"Holy Wisdom\"; or \"Sancta Sapientia\"; ) is a former Orthodox patriarchal basilica, later a mosque, and now a museum in Istanbul, Turkey. From the date of its dedication in 360 until 1453, it served as the Greek Patriarchal cathedral of Constantinople, except between 1204 and 1261, when... |
the zapatista movement | Ooh, I was just looking into this! So basically, they are a guerrilla group of (mostly agricultural and ethnically Mayan) farmers that seek to limit government and foreign incursions into Chiapas, the southernmost state of Mexico. Their ideology is "Neozapatism", a blend of Marxism, anarchism and Mayan culture. | [
"The Zapatista Army of National Liberation (\"Ejército Zapatista de Liberación Nacional\", EZLN) often referred to as the \"zapatistas\" is a revolutionary leftist group based in Chiapas, the southernmost state of Mexico. Since 1994, the group has been in a declared war \"against the Mexican state\", though this wa... |
why does american television show naked babies bottoms, but won't show a grown person's? | one is sexualized, one isnt. Some people will be aroused by feet anyway, its just how it goes. our society has decided baby butts are ok as long as they arent used in a sexual theme. If the watcher wants to find it sexual, thats their business.
with that said, you can find plenty of adult butts on tv, I recall NYPD... | [
"\"I never treated them as though they were in swaddling clothes,\" he said many years later of his young viewers. \"Most kid shows regard young viewers as babies. I wanted to treat them as their parents might if they were on TV.\"\n",
"Although child-sized bikinis appeared in the 1950s, in many European countrie... |
Why do the Indian and Chinese depictions of Buddha differ so much? | Are you referring to the fat Chinese Buddha? He's just a folklore deity named [Budai](_URL_2_), not a depiction of Siddhartha Gautama.
[This is one of the largest Buddha statue in Sichuan, China](_URL_1_), [here's a Buddha statue in Shaolin Temple](_URL_0_), and [here's a generic mass-produced Buddha statue](_URL_3_)... | [
"Although India had a long sculptural tradition and a mastery of rich iconography, the Buddha was never represented in human form, but only through Buddhist symbolism. This period may have been aniconic.\n",
"Although India had a long sculptural tradition and a mastery of rich iconography, the Buddha was never re... |
how are dubbing voices replaced without messing with background noises? | Basically, all the footage and sound effects are kept as separate files. These days there’s software that you can load these files into and then arrange and edit, and then the software will compile it all into the video that’s actually distributed to tv networks, streaming sites, or movie theaters. Different audio is t... | [
"Dubbing is occasionally used on network television broadcasts of films that contain dialogue that the network executives or censors have decided to replace. This is usually done to remove profanity. In most cases, the original actor does not perform this duty, but an actor with a similar voice reads the changes. T... |
why are people with a latex allergy also allergic to bananas? what's the connection? | The banana contains a protein which is very similar in chemical structure to latex. So if you're sensitive to one, there's about a 50% chance that you're sensitive to the other as well.
_URL_0_ | [
"People who have latex allergy also may have or develop an allergic response to some plants and/or products of these plants such as fruits. This is known as the \"latex-fruit syndrome\". Fruits (and seeds) involved in this syndrome include banana, pineapple, avocado, chestnut, kiwi fruit, mango, passionfruit, fig, ... |
How does x-ray powder diffraction work (specifically as applied to mineralogy)? | A powdered sample is still crystalline, and will still diffract x-rays to specific angles based on the lattice spacing. The size of the powder particles are still huge compared to the wavelength of x-rays. What powdering does is randomize your sample, so that all the different possible crystal faces of the material are... | [
"Typically, powder X-ray diffraction (XRD) is an average of randomly oriented microcrystals that should equally represent all crystal orientation if a large enough sample is present. X-rays are directed at the sample while slowly rotated which produce a diffraction pattern which show intensity of x-rays collected a... |
What's the difference between a tribe and an organized government in the medieval period? Why do we talk about the "Kingdom of Lombardy" or the "Duchy of Normandy", but at the same time we talk about the "Avars" or the "Aboriginal australians"? | I'm going to give two very short, simple answers and then one somewhat more complex (but still pretty short) answer. First short answer is that we say "Kingdom of Lombardy" and "Ducky or Normandy" because that is what they called themselves. Nine times out of ten the best term to use for a particular state or social gr... | [
"Lombardy is also divided in 1,546 \"comuni\" (municipalities), which have even more history, having been established in the Middle Ages when they were the main places of government. There are twelve provincial capital cities in Lombardy and twenty-four \"comuni\" have more than 40,000 inhabitants, most of which ar... |
can our brain switch it's perception of colors? | I dont have an answer, but everytime i get a high fever (102 F+) the way I perceive colors gets screwed up. I.E. I see the red digital numbers on my alarm clock as green. | [
"Perception of color depends heavily on the context in which the perceived object is presented. For example, a white page under blue, pink, or purple light will reflect mostly blue, pink, or purple light to the eye, respectively; the brain, however, compensates for the effect of lighting (based on the color shift o... |
Map of History | Is such a thing possible? No, not really. On a smaller scale, such a question has the problem of assuming defined states where there were none or where other arrangements would be more appropriate. On a larger scale, such a map would necessarily impose synchronous borders on areas that experienced consistent flux. Bor... | [
"Historical Atlas of the World is a historical atlas that contains 108 color maps showing religious boundaries, countries, cities, buildings army movements and expeditions. It contains an index to place, peoples, historical and military events and explorers. Covers the span from 3000 BC to ~1970 (Rhodesia, not Zimb... |
Ataturk and the Progressive Dictator | First off, I highly, highly, highly recommend you read Şukru Hanioğlu's new book Atatürk: An Intellectual Biography if you haven't already. I think that the principles you've outlined as characteristic of Atatürk deserve some modification. Semi-official Kemalist doctrine has six "arrows": Republicanism, Popularism, S... | [
"On 11 August 1930, Atatürk decided to try a multiparty movement once again and asked Ali Fethi Okyar to establish a new party. He insisted on the protection of secular reforms. The brand-new Liberal Republican Party succeeded all around the country. Without the establishment of a real political spectrum, once agai... |
how does a thermoelectric generator work? | What is really being asked is how the thermoelectric effect works, so I'll try and explain that. Imagine you had a metal wire that has either end held at a different temperature. The electrons in the metal act similar to a gas, where the electrons at the hotter end are moving faster and spreading out more. This causes ... | [
"BULLET::::- Thermoelectric generator – (also called thermogenerators) are devices which convert heat (temperature differences) directly into electrical energy, using a phenomenon called the \"Seebeck effect\" (or \"thermoelectric effect\").\n",
"A thermoelectric generator (TEG), also called a Seebeck generator, ... |
the urge to scratch wounds | The 'urge' is not evolutionary. It's a biological reaction to the wound.
The scab on the wound could be dry and cause an itch. Or the chemicals secreted by the body during the healing (histamines) could be the reason behind it.
| [
"Itch (also known as pruritus) is a that causes the desire or reflex to scratch. Itch has resisted many attempts to be classified as any one type of sensory experience. Itch has many similarities to pain, and while both are unpleasant sensory experiences, their behavioral response patterns are different. Pain creat... |
what is a tree made out of? | It comes from the air. The tree absorbs carbon dioxide from the air, uses the carbon to build the majority of its mass, and expels oxygen. | [
"Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic material, a natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xyl... |
eeg and erp | First read [this other ELI5-type post](_URL_0_) I wrote about how the brain works a few weeks ago, then come back here...
EEG is basically just a way of detecting which parts of the brain are active, moment-to-moment. They place these little "electricity detectors" all over your head. Now imagine that you have a parti... | [
"ERPs can be measured using electroencephalography (EEG), which uses electrodes placed on the scalp to measure the electrical activity of the brain. The ERP waveform itself is constructed from the averaged results of many trials (100 or more). The average reduces signal noise from random-brain activity, leaving jus... |
how does target make any money off their redcard debit? | They actually save money by doing so, they don't make money. So when a guest comes in and uses a card, other than a RedCard, the provider (Visa for example) will charge them a fee. By signing up for a card, they can avoid the fee altogether (debit), or reduce it drastically because they made a deal with MasterCard (cre... | [
"The Target Red Card program is a great example of how the value proposition works. Consumers enroll with Target, provide their checking account to be debited and receive 5% discount at the register when they use the Red Card to pay. Target saves the fees they would have otherwise paid to the payment networks and b... |
how is it physically possible for a mantis shrimp to punch so fast? | The punch of a Mantis shrimp really is incredible. There is no way that a mantis shrimp can punch that powerfully by muscle strength. Another mechanism is needed.
This is an ELI5 over-simplification, but the shrimp "cocks" it's specially designed exoskeleton, elastic tissues, and linkage systems and stores energy. ... | [
"Zebra mantis shrimp attack with a mean peak speed of 2.3 m/s and with a mean duration of 24.98 ms. This speed is significantly slower than those generated by the smashing mantis shrimp, who's strikes can reach 14-23m/s. However, it is similar to those of other aquatic predators attacking evasive prey. This discrep... |
how is it possible for some foods to pass through my digestive system and come out whole. i.e. corn and certain small beans | The brown (and the yellow in your pee, for that matter) are derived from byproducts of the breakdown of red blood cells in your body.
As far as corn, the outer shell of corn is cellulose, which our body is not good at breaking down. If you don't tear them apart with your teeth, then they can pass relatively unmoleste... | [
"The particles are sorted by yet another group of cilia, which send the smaller particles, mainly minerals, to the prostyle so eventually they are excreted, while the larger ones, mainly food, are sent to the stomach's cecum (a pouch with no other exit) to be digested. The sorting process is by no means perfect.\n"... |
How did the people of antiquity and medieval era record their music? | There's always more to be said on the topic, but while you're waiting check a look at these previous threads:
[*What did Roman music sound like and what form did the written notation take?*](_URL_3_) by u/racecar_ray
[*What do we know about Roman music?*](_URL_2_) by u/casestudyhouse22
[*What is the oldest form of m... | [
"The earliest Medieval music did not have any kind of notational system. The tunes were primarily monophonic (a single melody without accompaniment) and transmitted by oral tradition. As Rome tried to centralize the various liturgies and establish the Roman rite as the primary church tradition the need to transmit ... |
ramjet | Combustion engines need to compress the incoming air before it is burned. This does two things - it fits more air into the combustion chamber so that fuel can be burned at a higher rate, and it raises the temperature at which the combustion takes place, giving higher thermal efficiency.
A turbojet engine has a compres... | [
"A ramjet is a form of jet engine that contains no major moving parts and can be particularly useful in applications requiring a small and simple engine for high-speed use, such as with missiles. Ramjets require forward motion before they can generate thrust and so are often used in conjunction with other forms of ... |
how was the playstation 3 able to perform so well with only 256mb of ram? | PC run Windows OS that multipurpose generic OS that will consume 2+ GB of RAM on it's own plus there is other software running at the same time so with 4GB of there is not even 2GB left for the game.
The game on console can be fine tuned to specific configuration of the console. On PC it must be prepared to work with ... | [
"The original Z64 has a hardware set limit of 128 megabits. Because it is not capable of addressing any RAM above 16 megabytes, the user can not upgrade the RAM in order play bigger games. Once 256 megabit games became more prevalent, the parent company released hardware version 2.0 which includes a fully addressab... |
How far does one blood cell travel with one beat of an average healthy human heart? | Let's go with the typical (or not so typical) 70 kg man.
- Blood volume = ~5 liters
- Stroke volume (amount pumped with each beat) = ~70 mL
- Heart rate = ~ 75 bpm
- Cardiac output = ~5 liters/minute
- Height = 1.75 m (5'9")
The entire blood volume is circulated once a minute or so. I'd surmise that blood circulated... | [
"For a healthy human heart the entire cardiac cycle typically runs less than one second. That is, for a typical heart rate of 75 beats per minute (bpm), the cycle requires 0.3 sec in ventricular systole (contraction)—pumping blood to all body systems from the two ventricles; and 0.5 sec in diastole (dilation), re-f... |
Why was there such a push to annex Texas in the 1840's? | Let's go back a bit.
The Western Confederacy was beaten in the 1794 Northwest Indian War, and broken during the War of 1812. The Creeks collapsed into a brutal civil war in 1813, and Andrew Jackson razed the strongholds of the Creek and Seminole diehards during his 1816 invasion of Florida. The destruction of Negro F... | [
"The annexation of Texas was the chief political issue of the day. Van Buren, initially the leading candidate, opposed immediate annexation because it might lead to a sectional crisis over the status of slavery in the West and lead to war with Mexico. This position cost Van Buren the support of southern and expansi... |
you spray an ant with raid (or a similar product), what is actually happening to it while it is dying? | Different products contain different chemicals, but the active ingredient in normal Raid interferes with sodium channels. It prevents nerve cells from building up electrical charge by "breaking" the mechanism they use to transport electrically-charged particles, therefore causing paralysis and potentially "brain" damag... | [
"Insecticides may be repellent or non-repellent. Social insects such as ants cannot detect non-repellents and readily crawl through them. As they return to the nest they take insecticide with them and transfer it to their nestmates. Over time, this eliminates all of the ants including the queen. This is slower than... |
li5: could you please explain the phrase 'deus ex machina'? | It comes from when they used statues to represent gods in plays a long time ago. The machine part is because they were often lowered onto the stage with ropes and pulleys. They would often bring these onto the stage when the plot got stuck. The god would do something magic that solved a problem or moved the plot on. ... | [
"Deus ex machina (: or ; plural: \"dei ex machina\"; English ‘god from the machine’) is a plot device whereby a seemingly unsolvable problem in a story is suddenly and abruptly resolved by an unexpected and seemingly unlikely occurrence, typically so much as to seem contrived. Its function can be to resolve an othe... |
if men's body temperature is slightly higher than women's, why are men hairier? | Women don't actually have a lower body temperature than men - the heat is just distributed differently. Women's bodies are better at maintaining core body temperature at the expense of body temperature in the extremities.
Temperature also doesn't have much to do with hair. Human hair simply isn't effective insulation.... | [
"Modern men generally have more body hair than women, due to higher levels of androgens. However, both genders have less hair in the current era than they once had, due to evolutionary changes. Three different types of hair are present on the human body. Body hair, or androgenic hair, is the terminal hair that deve... |
how do airport scans actually work? | Congratulations on making it onto a watch list! Without saying anything too classified, density. Density of materials is almost like a finger print. | [
"Airport Surface Surveillance Capability (ASSC) is a runway-safety tool that displays aircraft and ground vehicles on the airport surface, as well as aircraft on approach and departure paths within a few miles of the airport. The tool allows air traffic controllers and air crew in cockpits equipped with Automatic D... |
In several of his books journalist Mark Kurlansky claims that the Basques might have discovered America before Columbus. Is there any truth to this? | I will quote a [post](_URL_0_) I wrote where I touched on Kurlansky's work:
>
> Mark Kurlansky in his pop-history (non-academic with no citations or references) works Cod and Basque History of the World for some reason strongly proposes the theories of Basque knowledge of North America, himself confesses the follo... | [
"One primary criticism of this theory is that if either a Sinclair or a Templar voyage reached the Americas, they did not, unlike Columbus, return with a historical record of their findings. In fact, there is no known published documentation from that era to support the theory that such a voyage took place. The phy... |
why don't countries invade other countries to take over land anymore? | What do you mean by 'anymore'?
The USSR was a little grabby and Russia continues to be.
Iraq invaded Kuwait in 1990, the Iran-Iraq war prior that was a pretty fucking big war.
India and Pakistan skirmish for land presently.
Israel continues to fight the Palestinians as well as an entire region, although not in an ... | [
"BULLET::::- Invading nations that are close to you carries a higher chance of success. The battlefields are close to your own country, thus it is easier for your troops to get supplies and to defend the conquered land. Make allies with nations far away from you, as it is unwise to invade them.\n",
"Others did ac... |
differences between catholic and episcopalian. | Episcopalian, barring from the basic beliefs (Belief in Jesus as God, Jesus will save you, Heaven and Hell) in general are very liberal.
Things such as: The Bible was written "under influence of God" rather than direct words, leaving room for context and interpretation.
Gays and women are allowed to be ordained, as ... | [
"The Episcopal Church follows the \"via media\" or \"middle way\" between Protestant and Roman Catholic doctrine and practices: that is both Catholic and Reformed. Although many Episcopalians identify with this concept, those whose convictions lean toward either evangelicalism or Anglo-Catholicism may not.\n",
"W... |
why do we experience discomfort/pain when we are exposed to light after waking up in the morning? | It's because of our pupils. Your eyes, even if they were closed while you were asleep, got used to the dark, so the pupils got big to allow more light in the event that you woke up in the dark, you could see better.
Well if you wake up to bright lights, that's a TON of light coming in and you can see ALL of it. So it... | [
"The proper exposure to light has become an accepted way to alleviate some of the effects of SAD. In addition exposure to light in the morning has been shown to assist Alzheimer patients in regulating their waking patterns.\n",
"Starting about two hours before an individual's regular bedtime, exposure of the eyes... |
why do people hate country music with a passion? | largely uncreative (not a large variety of topics), over produced, and i think most people hate the fans more than the music - similar to the emo hate. | [
"The country and western field of music is peculiarly for and about people and its music tells about people and their feelings. In the words of a famous critic: \"\"If a country singer can't feel what his audience is feeling, he's neither a country singer, nor a singer.\"\" The popularity of country music is, and h... |
Did the Cold War ever end? | This is a very interesting question. I'm not sure how helpful we can be, as the only people who'd be able to give you a decent answer don't exist yet. If you anticipate finding the secret to eternal life or passing your consciousness to a robot, and Reddit is still around several hundred years from now, set yourself a ... | [
"The Cold War Era has reached its endpoint as tensions between the two ideological rivals, the United States and the Soviet Union, have simmered down as a result of the dissolution of the latter and the massive change of political system among its allies.\n",
"The Cold War Era had reached its endpoint as tensions... |
why did the eli5 subreddit start off being full of extremely dumbed down, easy to digest, concise explanations when it started. now all the answers are like i'm reading doctoral thesis? what happened? | Several things to consider.
1) The easy and obvious questions have been asked to death. Simple questions are greeted by answers to just Google it.
2) The expanding user base has brought in experts in many fields. These people are able to provide much more accurate answers, at a reading comprehension level that fits b... | [
"In April 2013, the subreddit was threatened with a shutdown by Reddit admins after r/MensRights subscribers gathered personal information on a supposed blogger of feminist issues, and the subreddit's moderators advised members of the subreddit on how to proceed with this 'doxing' without running afoul of site rule... |
why do duracell and energizer batteries last so much longer than the off brand batteries? | Nice try, Duracell and Energizer joint venture salesman. | [
"Both Eveready and Energizer are marketed as different brands in some markets in Asia. This has led to the availability of both \"Eveready Gold\" Alkaline batteries and Energizer Alkaline batteries on store shelves. However, both are targeted at different market segments and Eveready batteries tend to be marketed f... |
Why was England so late in setting up colonies in the America's? Was it simple bad luck? Or something more political? | What do you mean "so late"? Englands first colonies were only about 100 years after Colombus. When you consider initial voyages took a year to get here and back, that the value of what was here was in doubt(indeed what was here period was unclear), that who owned it was unclear etc. its understandable the English would... | [
"England made its first successful efforts at the start of the 17th century for several reasons. During this era, English proto-nationalism and national assertiveness blossomed under the threat of Spanish invasion, assisted by a degree of Protestant militarism and the energy of Queen Elizabeth. At this time, howeve... |
Why does splashing your eyes with water, when you're sleepy, suddenly makes you more awake? | It's just a very minor cold shock response from your body. | [
"Water in the eye can alter the optical properties of the eye and blur vision. It can also wash away the tear fluid—along with it the protective lipid layer—and can alter corneal physiology, due to osmotic differences between tear fluid and freshwater. Osmotic effects are made apparent when swimming in freshwater p... |
why is the audio in porn videos so often not in sync? (nsfw) | Or better yet, is there a way to fix it? | [
"Porn groove is the music soundtrack to typical pornographic films, or a genre of music that imitates such music. The electric guitar with wah-wah pedal is the most common instrument associated with porn groove, and synonymous with the genre. Simple, often minimalistic-sounding drums, with the rimshot sound being c... |
My grandfather used to tell a story about WWII I always found interesting, does it have a basis in fact? | > That always preceded his feelings about the atomic bomb. He felt it was quite likely that he'd have been a part of and died in an invasion of mainland Japan, had it not been used. The implication being, none of us, his children and grandchildren, would have existed had the bomb not been dropped, since he didn't hav... | [
"Piers Brendon has called it \"the most appalling atrocity story\" of World War I, while Phillip Knightley has called it \"the most popular atrocity story of the war.\" After the war John Charteris, the British former Chief of Army Intelligence, allegedly stated in a speech that he had invented the story for propag... |
how is a degree from a place like harvard or yale any different from a degree in the same subject from somewhere else? | For starters, many of these places have good reputations because they have cutting edge research and the best academics who are at the forefront of their respective fields. It should be noted that this doesn't always translate to the best *teaching*, but that might well be beside the point.
Some economic theories of t... | [
"The degree programs from the school are offered jointly with other schools. Undergraduates can pursue a B.S. degree in Biology/Secondary Education, Physical Education (Teaching Track), or Social Studies Education, as well as a B.A. in Chemistry with Teaching Specialization or in Modern Languages (French, German, o... |
What is the longer-term background to Eritrean-Ethiopian tensions? | This is a complex question. Here's an answer to it, as far back as I could go in order to explain the shared heritage between the states and the rivalry that followed. For reference - Habesha is a term used to describe some, not all, of the peoples who inhabit Ethiopia and Eritrea. They speak Afroasiatic languages, wri... | [
"Relations between Eritrea and Ethiopia have been brittle and tensions between the two countries have remained high after both countries fought each other in the Eritrean–Ethiopian War which lasted from 1998 to 2000, and since the end of the war there have been a number of small border skirmishes between the two co... |
The brightness of the actual dark side of the moon? | Not much darker than a "dark sky" spot on Earth.
The Earth's atmosphere mostly reflects back urban light. But go out in the desert, or out at sea, at least 100 km away from any city and town - it's a pretty dark place. Luna wouldn't be very different - a bit darker maybe, but not much.
Most people have lived in citie... | [
"The Moon has an exceptionally low albedo, giving it a reflectance that is slightly brighter than that of worn asphalt. Despite this, it is the brightest object in the sky after the Sun. This is due partly to the brightness enhancement of the opposition surge; the Moon at quarter phase is only one-tenth as bright, ... |
when that university shooting happened in oregon everyone made a huge deal about not mentioning or even sowing the shooters face, now with the current shootings in sb why is his name and picture all over the nation? | I think its partly due to the perpetrators. The main reason they don't like to publicizes school shooters is that the shooters often do it for the personal notoriety. Its looking more and more like the SB attack was an act of terror or something similar so you can argue that the identify of the specific shooter is less... | [
"There was a significant national response to the shootings: hundreds of universities, colleges, and high schools closed throughout the United States due to a student strike of 4 million students, and the event further affected public opinion, at an already socially contentious time, over the role of the United Sta... |
How soon after the Big Bang did stars begin to form? | The first stars began to form about [150 million years](_URL_1_) after the Big Bang, during a period known as "reionization." Prior to this period were the "dark ages" where the universe was fairly uniformly filled with neutral hydrogen; since there were basically no charged atoms during this period, photons did not s... | [
"BULLET::::- 5 February – The first generation of stars is now thought to have emerged 560 million years after the Big Bang, according to scientists working on the European Planck satellite. This is 140 million years later than the previous estimate of 420 million years.\n",
"The first generation of stars, known ... |
Why did the various revolts of 1840's Europe fail? | From Jonathan Sperber 'The European Revolutions, 1848-1851'
-Revolution was heavily romanticized, revolutionary leaders often portrayed doing heroic deeds for the people. Lajos Kossuth from Hungary riding out and rallying peasantry or Giribaldi leading militias into battle.
-Some revolutionaries were incompetent... | [
"The Revolution of 1848 had major consequences for all of Europe: popular democratic revolts against authoritarian regimes broke out in Austria and Hungary, in the German Confederation and Prussia, and in the Italian States of Milan, Venice, Turin and Rome. Economic downturns and bad harvests during the 1840s contr... |
why can little caesars afford to sell pizzas at a low price while places like papa john's sells their pizzas for about double the price? | In every business there are some companies that focus on price, others that focus on making a better quality, and others that try to compromise. Little Caesars focus is very strongly on price, and they are willing to buy cheaper ingredients if that's what it takes. | [
"\"PMQ Pizza Magazine\" said in December 2016 that the company was the third-largest take-out and pizza delivery restaurant chain in the United States. (According to PMQ, Little Caesars is the third-largest pizza chain; however, it does not deliver.) The company's net profitability though, is far behind its main co... |
Has there ever been a government system that the majority of the population, across all economic divides, generally approved of? | I don't think your question can be answered because it's not clear what data would allow us to answer it.
Prior to modern times, we don't actually have the information to say whether the "majority of the population" "across all economic divides" approved of a particular government. We have information about whether pa... | [
"One factor in the social anatomy of these governments was the retention of a very substantial share in political power by the landed elite, the Junkers, resulting from the absence of a revolutionary breakthrough by the peasants in combination with urban areas.\n",
"Historically, most political systems originated... |
what are apis and why is "vulkan" apparently the next big thing for gaming? | Say you go to a mechanic for an oil change. If the mechanic is any good you don't need to give them step-by-step instructions on how to change the oil. Instead you just tell the mechanic to "change the oil" and trust that the mechanic knows what to do.
In the above example **you are specifying an end result without ha... | [
"Vulkan is a low-overhead, cross-platform 3D graphics and computing API. Vulkan targets high-performance realtime 3D graphics applications such as video games and interactive media across all platforms. Compared to OpenGL and Direct3D 11, and like Direct3D 12 and Metal, Vulkan is intended to offer higher performanc... |
Why is it so difficult to find a unifying theory in physics and why is it necessary? Can't it all work separately? | > Why is it so difficult
I could go into details of examples of current difficulties but that would just lead us astray from the real answer, which is: why should it be easy?
> Can't it all work separately?
Often it can in practice. For example you could have a theory that works well for slow speeds but badly at... | [
"\"Sometimes [...] people say that surely there's no final theory because, after all, every time we've made a step toward unification or toward simplification we always find more and more complexity there. That just means we haven't found it yet. Physicists never thought they had the final theory.\"\n",
"Consider... |
Could the amount of static electricity that shocks humans when they touch a doorknob be enough to kill an insect or other tiny creatures? | Static shocks have very high voltage (I remember reading somewhere that if you feel a shock, it's at least 10,000 Volts), but it has very little charge. You can think of it like trying to run a fire hose with an 8 oz glass of water; it might be at super high pressure, but it's not going to last very long. So the questi... | [
"Electricity is hazardous: an electric shock from a current as low as 35 milliamps is sufficient to cause fibrillation of the heart in vulnerable individuals. Even a healthy individual is at risk of falling from a high structure due to loss of muscle control. Higher currents can cause respiratory failure and result... |
If my salt intake is too high, can I just drink a lot of water to cancel it out? | Salt (Sodium) makes you retain water.
Adding water to a high salt diet means you'll be retaining lots of water.
This makes you hypertensive.
Hypertension (high blood pressure) is bad for pretty much everything.
Sorry, this turned out more ELI5 than science. | [
"Because more water is lost through pouch output, patients can get dehydrated easily and can also suffer salt deficiency. For this reason, some are encouraged to add extra salt to meals. Persistent dehydration is often supplemented with an electrolyte mix drink.\n",
"Too much salt intake in adults can also occur ... |
Was the Kansas/Missouri border war the start of the Civil War or just a precursor to it? | In 1820 the U.S passed the Missouri compromise that stated that slavery could not extend above the 36' 30" line. When Kansas and Nebraska were looking to join the union Stephen Douglas proposed a bill that would allow each state to vote on if they were going to be a slave state or a free state. Nebraska was far enough ... | [
"The 160-year-old rivalry between Kansas and Missouri began with open violence that up to the American Civil War known as Bleeding Kansas that took place in the Kansas Territory (Sacking of Lawrence) and the western frontier towns of Missouri throughout the 1850s. The incidents were clashes between pro-slavery fact... |
why can we see ultraviolet if it is outside the visible spectrum? | You can't.
If you shine UV on some things, like liquid laundry detergent, it makes the substance glow brightly. This is not you seeing UV, it is a substance absorbing UV photons and re-radiating the energy as visible wavelength photons you can see. | [
"Above the range of visible light, ultraviolet light becomes invisible to humans, mostly because it is absorbed by the cornea below 360 nm and the internal lens below 400 nm. Furthermore, the rods and cones located in the retina of the human eye cannot detect the very short (below 360 nm) ultraviolet wavelengths an... |
What was the point of the invasion stripes on planes during D-day? | They were identification aids for Allied pilots and gunners. Friendly fire was a persistent risk for aircraft, positive recognition being difficult in the heat of battle; the first Fighter Command losses of the war were in the "Battle of Barking Creek" during which two Hurricanes were shot down by Spitfires and the int... | [
"During World War II, \"invasion stripes\" were painted on Allied aircraft to assist identification in preparation for the invasion of Normandy. Similar markings had been used when the Hawker Typhoon was first introduced into use as it was otherwise very similar in profile to a German aircraft. Late in the war the ... |
why do circuit boards need transistors/what do they do? | You are thinking of capacitors.
Capacitors are used to regulate the energy flowing through a board. Rarely will you have a 'clean' energy flow. There will be dips and spikes along the way. The capacitors help smooth that out and provide a little extra juice and buffers to prevent jolts on or off from damaging the syst... | [
"Bipolar junction transistors offer high speed, high gain, and low output resistance, which are excellent properties for high-frequency analog amplifiers, whereas CMOS technology offers high input resistance and is excellent for constructing simple, low-power logic gates. For as long as the two types of transistors... |
why do particles behave so differently at the quantum level? | Our universe operates on two scales: macro and micro. We, as humans, sit in an awkward middle ground where both effects can be demonstrated.
There is a scaling effect in physics and engineering, in which mass and momentum increases cubically, while resistance increases to the square -- this is the result of volumetric... | [
"The fundamental feature of quantum mechanics that distinguishes it from classical mechanics is that particles of a particular type are indistinguishable from one another. This means that in an assembly consisting of similar particles, interchanging any two particles does not lead to a new configuration of the syst... |
How advanced was Polynesian navigation compared to other civilizations? | They presumably knew a great deal about stars, the movement of ocean currents and wave patterns, the air and sea interference patterns caused by islands and atolls, the flight of birds, the winds, and the weather. However, so did other navigators. It's still unclear how much of their exploration of *new* islands was ... | [
"Polynesian navigation used some navigational instruments, which predate and are distinct from the machined metal tools used by European navigators (such as the sextant, first produced in 1730; the sea astrolabe, from around late 15th century; and the marine chronometer, invented in 1761). However, they also relied... |
How credible is Noam Chomsky on American History/foreign policy | > I know his views on history can be controversial and don't want to discuss them, I'm just wondering if he uses correct info
Perhaps the biggest problem I have with Chomsky is that he's an unreliable source of historical information (and because of what he says about the self-brainwashing of US intellectuals, the r... | [
"Noam Chomsky mentioned The Purpose of American Politics during one of his talks criticizing it for a number of things. He cited Morgenthau who calls US intervention in Central America \"isolated forays\" and blames many critics of US historical record for \"committing a fundamental error of logic\" by confusing \"... |
What sort of cosmetics did the women of royalty/aristocracy wear during Henry VIII's reign? | Fashion, yes! Queen Catherine of Aragon (the first wife) is believed to have started the trend of wearing a farthingale (hoop skirt). The farthingale or verdugados in Spanish had been a staple of Spanish fashion for at least 20 years before Catherine came to England. When she got to England, it took about another ... | [
"The ideal standard of beauty for women in the Elizabethan era was to have light or naturally red hair, a pale complexion, and red cheeks and lips. Pale, white skin was desired because Queen Elizabeth was in reign and she had the naturally red hair, pale complexion, and red cheeks and lips. Also, it was to look ver... |
the russian subdivision system? | Russia is a union, much like the US is or the Soviet Union was. In fact, the official name of the country is not 'Russia', but the Russian Federation.
Republics are regions where the majority of the population is (or was, at the time of its creation) not ethnically Russian. They have partial autonomy, and their own co... | [
"In modern Russia, a selsoviet is a type of an administrative division of a district in a federal subject of Russia, which is equal in status to a town of district significance or an urban-type settlement of district significance, but is organized around a rural locality (as opposed to a town or an urban-type settl... |
Does our brain have a equivalent of binary code or pixels? | I'm not quite sure I understand your question. Neuronal firing can be thought of as a digital or binary process - they either fire or they do not. However, the relationship between input and output is non-linear. | [
"Most computers manipulate binary data, but it is difficult for humans to work with the large number of digits for even a relatively small binary number. Although most humans are familiar with the base 10 system, it is much easier to map binary to hexadecimal than to decimal because each hexadecimal digit maps to a... |
how do we instinctively know if something is good for eating? | It's not instinctive at all for humans. Look at babies, they put all sorts of non-edible items in their mouths.
What's good for eating is a learned behavior. We learn from our parents/society what is edible and what isn't.
> Give a dog and deer an apple. The deer will probably eat it as soon as he understand you don... | [
"BULLET::::- The safety of the food may be determined by observing whether or not the food taster subsequently becomes ill. However, food tasting is not effective against slow-acting poisons that take a long time to produce visible symptoms.\n",
"\"Our principles are simple: we use the best, nicest ingredients, t... |
It seems that the Victorian Era distorted our view of history, especially of women. Is there evidence of this? | What we think of as the modern discipline of history was born in the western 19th century. Historians always reflect the mores and concerns of their age. Both before and after Leopold von Ranke and his contemporaries, historians did not so much *actively suppress* women's lives so much as ignore them. This was for two ... | [
"She also charts the incidences of similar backlashes in American history, focusing on the women's movements of the Victorian era and after - the late 1840s, and the early 1900s, 1940s and 1970s. She shows that the same media reporting of adverse effects was present in each of these eras, as well as the same pressu... |
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