question stringlengths 3 301 | answer stringlengths 9 7.04k | context listlengths 7 7 |
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Why didn't Hitler tell Mussolini about his plans to invade the USSR? | This one is kind of complex.
[Operation Barbarossa](_URL_2_) was the operation the Axis had planned to invade the Soviet Union. Nazi Germany had started to amass troops and equipment and had a pretty substantial force at the border in February of 1941. The original plan for the operation was to take place in May of 1... | [
"Mussolini first learned of Operation Barbarossa after the invasion of Soviet Union had begun on 22 June 1941, and was not asked by Hitler to involve himself. Mussolini took the initiative in ordering an Italian Army Corps to head to the Eastern Front, where he hoped that Italy might score an easy victory to restor... |
what is cancer? (specifically leukemia) | You, my ELI5 friend, are made of cells. Billions and billions of them, and they all have special jobs, shapes, and grow a different rates.
Sometimes we want cells to grow and divide a lot, like skin cells. And sometimes we don't want cells to grow and divide a lot, like brain cells. Each cell knows, because it is in t... | [
"Cancer is a group of fatal diseases that involves abnormal cell growth that can invade or spread to other parts of the body. They are usually caused by the accumulation of mutations in genes that regulate cell growth and differentiation. Majority of cancer, about 90-95%, are due to genetic mutations from environme... |
why are neanderthals always depicted with caucasian features? | Most, if not all, skeletons found of Homo neanderthalensis were found in Europe, especially places like France. As you may know, the people native to most places in Europe are Caucasian, including people like the Gauls (the tribe whose descendents make up a quite large percentage of native French people). | [
"Neanderthals are depicted as white-skinned, while Cro-Magnons are dark. Kurtén's skin color identification for both populations appears to agree with recent DNA studies, including those proposing the African origin of modern humans. His racial presentation of the Cro-Magnon is in contrast to Jean M. Auel's view in... |
Urban abandonment during late antiquity and the middle ages. | In the case of the Roman empire, there are several possibilities:
- The loss of North Africa to the Vandals. North Africa was the breadbasket of the Western Roman Empire, and without it, huge cities could no longer be supported. There was a similar but less dramatic depopulation of Constantinople after Egypt was lost ... | [
"However, there are traces of a resettling in the Middle Ages (12th century), when the ancient Roman walls were incorporated into those of a building forming part of the new inhabited hamlet also called \"Saint Eleuterio\", then in turn abandoned.\n",
"This development took place in the Late Middle Ages (13th to ... |
why doesn't the us military replace the m9. i'm sure there are better pistols out there. | Military firearms tend to have a long life. They like to standardize. When you've got a million of *anything* it's a big deal.
That said, they're [currently looking into a replacement](_URL_0_). These things can take time. Since handguns haven't fundamentally changed in decades, there's no major rush. | [
"The U.S. Army and Air Force are seeking to replace their M9s through the Modular Handgun System program. The House Armed Services Committee wants to terminate the program in favor of upgrading the M9. Program officials say buying a new pistol is the better option due to advances in handgun designs, the difficulty ... |
apparently there are tens of thousands of illegal immigrants from ireland in places like new york. isn't life very difficult for them? how do they earn money? can they get things like houses, driving licenses, healthcare, etc? | Housing: rent and pay cash. Find landlord that doesn't care if you're illegal.
Driver license, just don't get one. Take bus or subway. Or drive illegally and not get pulled over.
Healthcare, go to emergency room, pay in cash or don't pay at all | [
"There are however numerous incentives which draw foreigners to the US. Most illegal immigrants who come to America come for better opportunities for employment, a greater degree of freedom, avoidance of political oppression, freedom from violence, famine, and family reunification.\n",
"Some people go to traffick... |
If our moon causes our tides, and considering the size, wouldn't moons around a planet the size of Jupiter have tides that would flood entire continents? | (not my field of expertise) The moons of Jupiter have huge tidal forces. For instance take Io, it's the closest large satelite of Jupiter and it's tidal forces are so extreme that they heat the core of the moon, causing volcanos with plumes hundreds of kilometers high!
_URL_0_
(I remembered all of this from Arthur C ... | [
"If the Earth had no Moon, the ocean tides resulting solely from the Sun's gravity would be only half that of the lunar tides. A large satellite gives rise to tidal pools, which may be essential for the formation of complex life, though this is far from certain.\n",
"Atmospheric tides are also produced through th... |
why do most aeroplane hangars have curved roofs regardless of their size? | Actually it is for strength. An arch is incredibly strong and puts far less strain on the materials than a flat surface. | [
"The rectangular hangar accommodates 10 planes, and is still in use today. The building is made of brick and has a concrete foundation. The roof is gabled, and the walls are parapeted. The end walls are capped by pent roofs and decorative brick panels framed by stucco. The north and south ends contain eight large s... |
What is the mythological precedent for Jesus's single resurrection? | To quote Mettinger's [The Riddle of Resurrection](_URL_0_), which is probably the best survey of ANE gods and resurrection (Baal, Dumuzi-Tammuz, Adonis, Melqart-Heracles, Osiris, Eshmun-Ascelpius):
> The dying and rising gods were closely related to the seasonal
cycle. Their death and return were seen as reflected i... | [
"Rahner states that the death and the resurrection of Jesus are two aspects of a single event not to be separated, even though the resurrection is not a historical event in time and place like the death of Jesus. What the Scripture offers are powerful encounters in which the disciples come to experience the \"spiri... |
Since pi is irrational, is there a point in pi's decimals where there are 1 billion subsequent threes? | Probably, but not just because it's irrational. For example, the [Liouville constant](_URL_1_) is irrational but has only 0's and 1's in its decimal expansion.
However, pi is strongly conjectured to be a [normal number](_URL_0_). If this is the case, you certainly can find a billion 3's in a row in its decimal expansi... | [
"as it sometimes is, the ellipsis does not mean that the decimals repeat (they do not), but rather that there is no end to them. It has been proved that is irrational. Another well-known number, proven to be an irrational real number, is\n",
"In the 1760s, Johann Heinrich Lambert proved that the number (pi) is i... |
how are the nsa intercepting my data? | > Assuming I am US, by what method did the NSA just get hold of either/both the credit card details and travel information?
So the NSA is a spying agency, that also is involved in technical standards. They have court oversight through FISA, who can issue warrants that compel companies to turn over data.
Lets walk... | [
"All intercepted data go to the NSA headquarters in Fort Meade, Maryland, where a program called XKeyscore processes them and sending them to different so-called \"production lines\" that deal with targets, like counterterrorism or specific countries. These processed data are stored in different NSA databases like ... |
why does increased air flow extinguish flames? wouldn't you be adding the necessary ingredients? | Yer not alone in askin', and kind strangers have explained:
1. [ELI5: Why can air both extinguish and stoke up a fire? ](_URL_2_)
1. [ELI5: Why does blowing air on a small flame put it out, but doing the same on a big fire only fuels it? ](_URL_1_)
1. [ELI5: Why does blowing on a flame put it out, but glowing on coals... | [
"Oxygen is not flammable, but when it is present in increased concentrations it will enable fires to start much more easily. Once a fire has started, if supplemental oxygen is present it will burn more fiercely, based on the principle of the fire triangle. Materials that do not burn in ambient air may burn when the... |
why do people feel comfortable with themselves in the mirror, but hate themselves in flipped pictures? | Short answer: Because mirrors show a mirrored version of your face that you are used to/comfortable seeing. Photographs show a "correct" version of your face where it is not mirrored and it looks off to the person who perceives sees their face in a mirror on a regular basis
_URL_0_ | [
"This psychological effect is often used in the cinema, where an actor will be shown apparently looking at himself or herself in the mirror. What viewers see is different from what the actor sees, because the camera is not right behind the actor, but the position of the actor is often chosen so that his or her imag... |
If I could fly and I flew upwards really slowly, could I escape the earths atmosphere? | The term escape velocity refers to the speed you need to never fall back down to the Earth, assuming you stop pushing on your craft. If you can somehow continue to travel with a constant force away from the Earth, there is nothing stopping you from coming back down. Real craft will eventually run out of fuel, and thus ... | [
"As a tool for learning to control the body flight, there is a vertical wind tunnel, which makes it possible to fly in the air, simulating free fall due to the created air flow (on average, about 190 km/h).\n",
"In most situations it is impractical to achieve escape velocity almost instantly, because of the accel... |
American WW1 vet grave markings. | That's his unit. Company A, 13th Machine Gun Battalion.
See page 76 of this PDF
_URL_0_ | [
"When their remains were recovered after the war, Farrow, Hallmark and Meder were buried with full military honors at Arlington National Cemetery. Spatz was buried with military honors at National Memorial Cemetery of the Pacific.\n",
"The cemetery is an official Commonwealth War Grave Cemetery containing 48 memo... |
-if lance armstrong and his generation were doped to the gills how is it that this generation of cyclists is breaking their records absent significant technology advances and without drugs. | what records are you referring to exactly? if we're talking about the time it takes to climb Ventoux or Alpe d'Huez, [those times have actually gotten markedly worse since the doping crackdown](_URL_2_). in both cases, the best certifiably clean result isn't in the top 10 times up those climbs. or the top 20 (i'm looki... | [
"In 2009 director Alex Gibney set out to film \"The Road Back\", a documentary on cyclist Lance Armstrong's comeback year after a four-year retirement from the sport. Three years later, on October 2012, a doping investigation led to his lifetime ban from competition and the stripping of his seven Tour de France tit... |
why do people think that jeffrey epstein’s death seems like a coincidence? | At this point he was ready to bring down the people around him with him. He was a liability for all of the guilty elites that took advantage of his services. He already almost died once due to a cop beating him senseless, so this isn’t that big of a surprise. | [
"Epstein died of an overdose of Carbitral, a form of barbiturate or sleeping pill, in his locked bedroom on 27 August 1967. He was discovered after his butler had knocked on the door and then, hearing no response, asked the housekeeper to call the police. Epstein was found on a single bed, dressed in pyjamas, with ... |
why do bad smells seem to be so much more resilient than good ones? | I would assume that it is because bad smells are most often things that can negatively affect our health, like feces and rotting food and we should avoid as long as it is around.
The running shoes example doesn't exactly fit, although that may be due to cultural/evolutionary distance from apes in the same way that sw... | [
"Smell disorders can result in the inability to detect environmental dangers such as gas leaks, toxins, or smoke. In addition to safety, nutritional and eating habits can also be affected. There is a loss of appetite because of unpleasant flavor and fear of failing to recognize and consuming spoiled food. A decreas... |
when i bend my little finger, why do my other fingers also move? | What happens between the pinky and ring finger is nerve signals sent to the pinky get picked up by the ring finger because your brain can't actually control the pinky very accurately so to do more it sends signals intended for the ring finger. All of your fingers do this to a degree. Try extending all your fingers, and... | [
"Thumb twiddling is an activity that is done with the hands of an individual whereby the fingers are interlocked and the thumbs circle around a common focal point, usually in the middle of the distance between the two thumbs.\n",
"You should hold the other two fingers slightly bent, not completely straight. This ... |
If the gene that causes dwarfism is dominant why is it that the percentage of the general population that have this dominant gene is not higher? | Inheriting two copies of the gene usually leads to death in infancy [1], and a lot of achrondroplasic dwarfs have chronic pain, which would cause a general decrease in "fitness" (in the Darwinian sense). It seems fair to say it probably puts people at a pretty serious sexual disadvantage as well.
1. _URL_0_ | [
"As the genetic mutations that cause dwarfing occur in many species, dwarf animals can be the offspring of normal-appearing animals. Even in breeds which have not been selected for dwarfing, some genetic lines may show a tendency to produce dwarfs, which may be encouraged by deliberate breeding. This often takes th... |
Can a strong enough electric field penetrate Faraday cage? | A Faraday cage works because the electrons in the cage respond to an external electric field and re-arrange themselves naturally to create an equal and opposite field.
Hypothetically, if you had a large enough externally applied field that all the free electrons moving from one side to the other does not produce a lar... | [
"Faraday cages cannot block stable or slowly varying magnetic fields, such as the Earth's magnetic field (a compass will still work inside). To a large degree, though, they shield the interior from external electromagnetic radiation if the conductor is thick enough and any holes are significantly smaller than the w... |
Why is steel stronger than pure iron? | It all comes down to grain structure. Neither steel nor iron is a completely homogenous solid. A single crystal of metal can deform easily along the crystal axes; but if your metal is made up of a large number of small crystalline regions that are oriented randomly, they can't all deform in the same way and the bulk ma... | [
"Steel has much higher strength than wrought iron and allowed long span bridges, high rise buildings, automobiles and other items. Steel also made superior threaded fasteners (screws, nuts, bolts), nails, wire and other hardware items. Steel rails lasted over 10 times longer than wrought iron rails.\n",
"Iron is ... |
in court how do they compensate swearing the oath on bibles for people who arent religious or are not christian? | In the US, very few jurisdictions have people swear on bibles anymore. Those that do offer alternates to non-Christians. Some religions, like the Jehovah's Witnesses, who do not allow swearing, are allowed to affirm instead.
Note there is no legal significance to swearing on the bible or any religious book, it is pu... | [
"On May 24, 2007, Superior Court Judge Paul Ridgeway ruled that people of non-Christian faiths must be allowed to use religious texts other than the Christian Bible when being sworn in as jurors or witnesses in state court proceedings. Though the state had 30 days to decide to appeal the ruling, it took no action.\... |
What is it about Jamaican culture - opposed to other Caribbean nations - that produced so much extraordinary music? | Not to stifle discussion, but /u/hillsonghoods wrote [some fantastic replies to a similar question](_URL_0_) of mine which I'd recommend checking out. | [
"Jamaica's most popular musical forms are reggae and dancehall. There are also others such as \"dub poetry\" or chanted verses, Ska, and Rocksteady, with its emotionally charged, celebrative beat. Jamaican Americans also listen to a great variety of other music such as: jazz, calypso, soca, ska, rap, classical musi... |
What do we know about the Helots before they were enslaved by the Dorians/Spartiates? Did they ever manage to liberate themselves? | The ancient sources for helots are of such paucity and quality that scholars keep getting to diametrically opposite conclusions about who they were, what was their servial status, and the timing of their servitude. If you're interested in Helotry, I'd recommend this [collection of essays](_URL_0_), edited by Susan E. A... | [
"In the \"Bibliotheke\", \"Dorus received the country over against Peloponnese and called the settlers Dorians after himself.\" According to Karl Kerenyi, the Dorians recalled that three times Heracles had aided their \"oldest king\", Aigimios, \"under whom they had not yet emigrated to the Peleponnesos.\" Kerenyi'... |
how do we get propane and other gases from the ground? | We refine crude oil which contains gases in the oil(similar to carbonated beverages but less fizzy) and can undergo chemical reactions which will take bigger molecules and break them down into smaller molecules, like propane, which we then seperate out. | [
"Propane and butane are gases at atmospheric pressure that can be liquefied at fairly low pressures and are commonly known as liquified petroleum gas (LPG). Propane is used in propane gas burners and as a fuel for road vehicles, butane in space heaters and disposable cigarette lighters. Both are used as propellants... |
Does picking up a radio signal with a antenna reduce the power of the signal, even minimally? | Substitute "radio signal" with "sunlight" and "antenna" with "solar cell".
You assume that there's such thing as _the_ power of the signal, as a property of the emitter that everyone has direct access to. No, radio waves are not fundamentally different from light, so what you have instead is independent power of the s... | [
"So much wasted power is not acceptable in a transmitting antenna, however in a receiving antenna the inefficiency is not important at frequencies below about 15 MHz. At these lower frequencies, atmospheric noise (static) and man-made noise (radio frequency interference) even in the weak signal from an inefficient ... |
Does running through the rain make you more or less dry than walking? | If you look at this problem by trying to figure out your wetness as you walk through the falling rain, then it can be pretty tough. But it actually becomes easier if you look at it from the frame of reference of the falling rain. In this reference frame, the rain is just sitting there, still, and the ground is moving u... | [
"Running is an effective way to reduce stress, anxiety, depression, and tension. It helps people who struggle with seasonal affective disorder by being more outside running when it's sunny and warm. Running can improve mental alertness and also improve sleep which is needed for good mental health. Both research and... |
why do stenographers use those tiny typewriters? | They're [stenotypes](_URL_0_) which are much faster than typing, but don't transcribe speech directly into readable English but into a form of shorthand.
Why? It's quicker - the words are formed with "chords" rather than letter at a time. | [
"A number of typographical conventions originate from the widespread use of the typewriter, based on the characteristics and limitations of the typewriter itself. For example, the QWERTY keyboard typewriter did not include keys for the en dash and the em dash. To overcome this limitation, users typically typed more... |
how did the wwii enigma code machines work? | It's pretty cool, actually. I'll start with the basics. Each letter on the keyboard is connected, or paired, to another letter. So, if you press the A key, for example, you might see K light up. Similarly, if you press K, you'll see A light up. So, if you were to press H-E-L-L-O, you might get something like T-W-I-I-M.... | [
"In the lead up to World War II, the Germans made successive improvements to their military Enigma machines. By January 1939, additional rotors had been introduced so that there was a choice of three from five (i.e. 60 wheel orders) for the army and airforce Enigmas, and three out of eight (336 wheel orders) for th... |
the lean six sigma methodology | LEAN and 6sigma address two different aspects of factory production.
LEAN applies analysis to find the minimal cost steps needed to produce the item. It could mean the difference between giving a power tool to a worker instead of a manual tool. or having a conveyer delivery belt move the component to the worker in... | [
"Lean Six Sigma is a synergized managerial concept of Lean and Six Sigma. Lean traditionally focuses on the elimination of the eight kinds of waste/\"Muda\" classified as defects, over-production, waiting, non-utilized talent, transportation, inventory, motion, and extra-processing. Six Sigma seeks to improve the q... |
how do the "check to ensure you're not a robot" things actually work? what prevents computers from "clicking all pictures with a car"? i'm especially confused with the ones that dont require you to do anything except check the box. does somebody have an explaination? | It checks the way that the person clicks the button (path, speed, etc) to determine if the clicker is indeed a human | [
"Machine checks are a hardware problem, not a software problem. They're often the result of the overclocking or overheating, causing errors, or hitting a thermal limit where the CPU must shut itself down to avoid permanent damage. But they can also be caused by bus errors introduced by other failing components, inc... |
how did mayweather win that fight? | Pacquiao was the aggressor for most of the fight, and he swung a lot more. The crowd was clearly on his side, and Mayweather rarely drove forward.
But these things don't matter to the judges, or at least they shouldn't. Who was better at landing punches, who dictated the pace, who did the most damage, these things ma... | [
"Having recovered from Pacquiao's big hit in the previous round, Mayweather won the early exchanges of the fifth round. Pacquiao remained on the offensive, but was unable to land any big punches. Mayweather upped his activity and won the round in the eyes of the three judges. Pacquiao came out aggressive in the six... |
at the large hadron collider, how do the scientists get the 'right' protons into the machine? | You're overthinking the way it actually works.
What happens is they use a source that generates literally billions and billions of protons, these are all then accelerated around the machine and then finally allowed to crash into each other. Most of them don't even hit each other and are just absorbed. If the scientist... | [
"The Proton Synchrotron Booster (PSB) is the first and smallest circular proton accelerator (a synchrotron) in the accelerator chain at the CERN injection complex, which also provides beams to the Large Hadron Collider. It contains four superimposed rings with a radius of 25 meters, which receive protons with an en... |
What was the origin and meaning behind the haircuts of Medieval Japan? | Frankly I only know of the common topknot ("Chonmage") which was mostly done as a way to ensure that the kabuto helmet would fit snugly on one's head. The idea was that the topknot would be able to fit through a small hole in the helmet. Over time, while this tradition was forgotten, as the bushi and local daimyo beg... | [
"In the early 1870s, in a shift that historians attribute to the influence of the West, Japanese men began cutting their hair into styles known as jangiri or zangiri (which roughly means \"random cropping\"). During this period, Asian women were still wearing traditional hairstyles held up with combs, pins and stic... |
(if your country has them) why do drinks in king-size cans cost less than the normal cans? | There are a lot of fixed costs in packaging drinks and the price of a bigger or smaller can may not make much difference. Most of an items price has nothing to do with the size.
I designed labels for a big box store once and learned that the difference in cost to make a 16oz can of soda and a 32oz can is often less th... | [
"In both Malaysia and Singapore, the most commonly found cans are 300 ml for non-carbonated drinks and 325 ml for carbonated drinks. Larger 330 ml/350 ml cans are limited to imported drinks where it would usually cost a lot more than local ones.\n",
"250 ml cans are the most common for soft drinks, but when accom... |
4 continuous hours in the sun results in a sunburn, but 4 hours broken up into 15 minutes chunks does not. | The explanations so far are not correct. 4 continuous hours of sunlight will give your damaged cells less time to repair DNA and less time to apoptose (safely die without causing inflammation).
4 hours spread out over increments gives your cells time to repair DNA and, if need be, apoptose irreparable cells in-between... | [
"Sunburn can occur in less than 15 minutes, and in seconds when exposed to non-shielded welding arcs or other sources of intense ultraviolet light. Nevertheless, the inflicted harm is often not immediately obvious.\n",
"Recurring yearly, the eruption can sometimes last longer than a few days if persistent and rep... |
what are these new-age solid-state batteries? how are they different from conventional batteries? | They're batteries that use solid electrodes or electrolytes instead of liquid.
They have potentially higher energy density, and are safer since they're not flammable. They also have longer lifespans and don't produce as much heat.
I think the problem at the moment is that they're not ready to be mass produced and so ... | [
"A solid-state battery is a battery technology that uses solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium-ion or lithium polymer batteries. Materials proposed for use as solid electrolytes in solid-state batteries include ceramics (e.g. oxides, sulfides, p... |
When I think of the legacy of dueling, I picture it as an exclusively male enterprise. Is this really the case? Or are there records of women dueling as well? | Not discouraging any new answers coming in, but you better believe that /u/Georgy_K_Zhukov wrote about [this topic already](_URL_0_). Hope it helps! | [
"In tennis, \"Battle of the Sexes\" is a term that has been used to describe various exhibition matches played between a man and a woman (or, in one case, a doubles match between two men and two women). Most famously, the term is used for a nationally televised match in 1973, held at the Houston Astrodome, between ... |
how does a bike roll down a hill (balance) with no assistance? | Conservation of angular momentum. The wheels of the bike are spinning on a particular plane, and they naturally "want" to continue spinning on that plane, so they resist any change in that motion. In this case they resist the bike tipping over due to gravity. The faster they are spinning (meaning the more momentum they... | [
"A cyclist executing a basic track stand holds the bicycle's cranks in a horizontal position, with his or her dominant foot forward. Track stands executed on bicycles with a freewheel usually employ a small uphill section of ground. The uphill needs to be sufficient to allow the rider to create backward motion by r... |
why (in the u.s) we are taxed twice, and in many cases a third time, on the same income? | There's nothing illegal for different taxation at different levels of government for different purposed. Different taxes are for different governing bodies, some are more regressive, some more progressive, some go to specific uses while others go to general revenue streams. The amount needed to be collected is the same... | [
"Taxes are most often levied as a percentage, called the \"tax rate\". An important distinction when talking about tax rates is to distinguish between the marginal rate and the effective tax rate. The effective rate is the total tax paid divided by the total amount the tax is paid on, while the marginal rate is the... |
the "internet" to someone from the 1950s | Basically just go over the history of computers so that each step is easy enough to imagine from the last:
You know adding machines? Well we've made them better. Much better. Instead of being mechanically constructed to do sums or other things with numbers we enter with some buttons we've extended them to be able to d... | [
"The history of the Internet begins with the development of electronic computers in the 1950s. Initial concepts of wide area networking originated in several computer science laboratories in the United States, United Kingdom, and France. The U.S. Department of Defense awarded contracts as early as the 1960s, includ... |
I was told that there is so much historical proof of jesus' ressurection that you can't claim it didn't happen, how true is this? | **Commenters:** Please keep our commenting rules in mind as you respond to this. We've already had to remove a lot of comments that weren't up to the standards of the subreddit.
**OP:** We actually have this question asked from time to time, or questions like it. You might be interested in these previous posts:
* [S... | [
"Many testified falsely against Jesus, but their statements did not agree. At last two witnesses said they had heard Him saying He would destroy that temple and in three days built another, not made with hands, (He really had meant the resurrection of His body, as a temple of the Holy Spirit, destroyed by others bu... |
Can we create artificial atmospheres? | It's hard, because planets are big.
Think about what an atmosphere is. It's an razor thin envelope of gas that wraps around the surface of a rocky planet. There's no way to *fake* that. You don't want an *artificial* atmosphere, so much as you are actually asking for a real *bona fide* atmosphere.
To give the moon a... | [
"There are two basic choices for an artificial atmosphere: either an Earth-like mixture of oxygen in an inert gas such as nitrogen or helium, or pure oxygen, which can be used at lower than standard atmospheric pressure. A nitrogen-oxygen mixture is used in the International Space Station and Soyuz spacecraft, whil... |
why do space craft enter the atmosphere at full velocity, requiring heat shields and risking burning up? | "at the expense of additional fuel"
That's a really big expense, both in cost and weight. Its just literally not economically viable right now to do it that way. Though things like space x are starting to work on it.
Right now it makes most economic sense to just let it burn and crash and rebuild it, because thats ho... | [
"Spacecraft that land on a planet with an atmosphere, such as Earth, Mars, and Venus, currently do so by entering the atmosphere at high speeds, depending on air resistance rather than rocket power to slow them down. A side effect of this method of atmospheric re-entry is aerodynamic heating, which can be highly de... |
the earth is about 4.5 billion years old, but at what physical point do scientists classify a planet's age as 0? | When it started to be a planet.
To be a planet, it needs to fit three criteria:
A planet is an object in orbit around the Sun with a diameter greater than 2000 km.
A planet is an object in orbit around the Sun whose shape is stable due to its own gravity.
A planet is an object in orbit around the Sun that is domina... | [
"The age of the Earth is estimated to be 4.54 ± 0.05 billion years This age may represent the age of the Earth's accretion, of core formation, or of the material from which the Earth formed. This dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric age... |
How much body heat do you lose in your legs compared to your arms? And in your hands and feet? | heat loss is fairly uniform throughout the body. | [
"The burn percentage in adults can be estimated by applying the Wallace rule of nines (see total body surface area): 9% for each arm, 18% for each leg, 18% for the front of the torso, 18% for the back of the torso, and 9% for the head and 1% for the perineum.\n",
"Normally, extremities such as the hands are lower... |
Theoretically could you implant cones into your eyes that would allow you to see colors you could previously not see? | Perhaps. Experiments have been done where new visual pigment proteins have been introduced into red-green colorblind monkeys, and afterwards the monkeys could distinguish colors that they were not able to previously. However, these experiments did not implant new cones into the monkey retinas. Instead new proteins were... | [
"Neitz further states that since apparently \"the neural circuits can handle even higher dimensions of color vision that could come from artificially adding a fourth cone type, it is possible that gene therapy could also be used to extend normal human color vision\", making human trichromats into tetrachromats.\n",... |
Was Russia/Stalin truly hoping to share the Europe with Germany/Hitler or was Stalin playing a waiting game? | First of all let me say that Stalin didn't leave a diary so we can't exactly say what his emotions or personal thoughts were with confidence. That said, he was probably neither of those things.
The idea that he locked himself in a room for 3 days is certainly not true. We do have a record of his itinerary of the firs... | [
"The Soviet Union was not invited to the critical Munich conference in late September 1938, where Britain, France and Italy appeased Hitler by giving in to his demands to take over the Sudetenland, a largely German-speaking area of Western Czechoslovakia. Distrust was high in all directions. Leaders in London and P... |
What is happening on a microscopic level when I burn my toast? | [The Maillard Reaction](_URL_0_) | [
"The naked eye detects particle sizes greater than 7 µm (micrometres). Visible particles emitted from a fire are referred to as smoke. Invisible particles are generally referred to as gas or fumes. This is best illustrated when toasting bread in a toaster. As the bread heats up, the products of combustion increase ... |
If I weigh X and add Y weight to my body during exercise, do I burn the same calories as a person who weights X+Y? | You will be burning slightly fewer calories. The reason for this is that all body mass needs to burn calories constantly to maintain normal life processes, but if you put on the vest, the vest would not need to burn calories. | [
"A permanent routine of exercise, eating healthily, and, during periods of being overweight, consuming the same number or fewer calories than used will prevent and help fight obesity. A single pound of fat yields approximately 3500 calories of energy (32 000 kJ energy per kilogram of fat), and weight loss is achiev... |
Why is it when I close one eye, the vision in my open one appears to have "Warm" colors, and the other appears to have "Cool" colors? | My photography expertise is usable here!
So see this. When you close an eyelid, the sunlight is filtering trough a blood lined flap of skin. This makes the "warm"(sub 4300kelvin" light look even warmer.
See, our eyes adjust the "white balance" of our surroundings. That's why when you walk into a room lit with compa... | [
"Warm colors (red, orange, and yellow) are signs of warmness and can increase the temperature in a confined area. These colors are associated with danger, threat, warning, and movement and the way they affect the brain they increase metabolism and heat in the body and put it on alert which from Iranian traditional ... |
Would someone please explain the whole "tiny curled up extra dimensions" thing? | Okay. So. Dimensions. What is a "dimension?" If you go by bad science-fiction B-movies, a "dimension" is a sort of parallel plane of existence, one that intersects but is distinct from our own.
This is absolute, unfettered nonsense, so go ahead and put it out of your mind for now.
What a "dimension" *actually* is is ... | [
"The many-angled ones exist in a space with more dimensions than our own; hence, they appear to be \"many angled\". As a result, when they manifest in our universe they appear as disconnected floating body parts of some larger beast that is complete in the higher dimension (similar to how a three dimensional being ... |
What was going on in China that so many of them migrated to work for the railroads in the U.S.? | The Taiping Rebellion started in 1850. It was fairly bloody, even by Chinese standards. The effects of that rebellion also inspired others to rebel and there were associated problems with flooding and famine. _URL_0_ | [
"Starting with the California Gold Rush in the middle 19th century, the United States—particularly the West Coast states— enlisted large numbers of Chinese migrant laborers. Early Chinese immigrant worked as gold miners, and later on subsequent large labor projects, such as the building of the First Transcontinenta... |
what did it cost to go see an actual mozart opera? | I can't seem to find any really solid sources right now, and all my books are still at school (I'm home from college on break right now), but I have studied music history quite a bit, so I can at least give you an answer to your question, even though I can't really give you further places to look currently. I can also ... | [
"Although the opera greatly raised Mozart's standing with the public as a composer, it did not make him rich: he was paid a flat fee of 100 Imperial ducats (about 450 florins) for his work, and made no profits from the many subsequent performances.\n",
"The Imperial Italian opera company paid Mozart 450 florins f... |
why do ladybugs seem to appear inside every time the temperature drops? | These insects, among quite a few others are doing something called over wintering. I'm short, they are looking for shelter. Homes/buildings are about the best fit for that. So as the temp drops they look for these places to survive. You'll actually end up seeing activity change with temp, sometimes with recurrences!
T... | [
"A newly hatched ladybug is bullied by group of flies and attempts to fly away, but the flies chase after it. The ladybug crashs and breaks off a wing. Unable to locate its family, the ladybug shelters in a tin for the night. The tin is full of sugar cubes, part of an abandoned picnic. In the morning, various bugs ... |
why are pretzels shaped like... well, pretzels? where did that shape originate from? | Can't remember specifics but something about nuns creating a shape that looked like children folding arms. | [
"A pretzel () () () is a type of baked bread product made from dough most commonly shaped into a twisted knot. The traditional pretzel shape is a distinctive symmetrical form, with the ends of a long strip of dough intertwined and then twisted back into itself in a certain way (a pretzel loop). In modern times, pre... |
why does software randomly not work or crash at times but is fine after a restart? | Computer programs ALWAYS have bugs, it's the nature of programming as software is usually so complicated with thousands upon thousands of lines of code, some situations weren't thought about or someone just made a mistake when making it. Little bugs often exist that cause programs to become unstable over time, and the... | [
"Crash-only software also has benefits for end-users. All too often, applications do not save their data and settings while running, only at the end of their use. For example, word processors usually save settings when they are closed. A crash-only application is designed to save all changed user settings soon afte... |
how is it possible for light to not have reached us from parts of the universe yet? | The limit of Speed of Light only applies to particles moving through spacetime, it does not apply to spacetime itself. Two points in spacetime can be pushed apart by the expansion of the universe faster than the speed of light. The further any two points in spacetime are from each other, the faster they move apart base... | [
"Some parts of the universe are too far away for the light emitted since the Big Bang to have had enough time to reach Earth or its scientific space-based instruments, and so lie outside the observable universe. In the future, light from distant galaxies will have had more time to travel, so additional regions will... |
How do athletes seemingly tear their ACLs so easily during non-contact portions of their respective sports? | The others posting here have done a really good job of explaining so far, but I'll fill in with a little more information.
The ACL is most commonly torn when the knee bends backwards too far, or moves too far to the side. This is easily something you can do yourself, simply by turning sharply, stopping, any number of... | [
"One sports injury that is becoming prevalent in contact sports, particularly in the sport of American football, is called a \"stinger.\" An athlete can incur this injury in a collision that can cause cervical axial compression, flexion, or extension of nerve roots or terminal branches of the brachial plexus. In a ... |
How do we know how many people died under Stalin and Mao? | We honestly don't know accurately, it's mostly educated guesses and deduction, some will be higher than reality and some will be lower than the true number. It's just like with most things in history, I will give an example, with The Battle of the Nile, we know how many British were involved, how many died and how many... | [
"The number of people killed under Mao's rule in the People's Republic of China has been estimated at 19.5 million by Wang Weizhi, 27 million by John Heidenrich, between 38 and 67 million by Kurt Glaser and Stephan Possony, between 32 and 59 million by Robert L. Walker, 50+ million by Steven Rosefielde, 65 million ... |
how to become a programmer when /r/learnprogramming goes over my head? [serious] | Just how far over your head are we talking? Do you have any sort of math background? Do you know what a computer is?
You might try to start with some sort of interactive tutorial like [Code Academy](_URL_0_) or a book that's meant to teach everything from the ground up. | [
"A programmer who needs to implement a specific algorithm, especially an unfamiliar one, will often start with a pseudocode description, and then \"translate\" that description into the target programming language and modify it to interact correctly with the rest of the program. Programmers may also start a project... |
how do professional boxers have (decently) long careers if they're getting concussed everytime they fight? | _URL_0_
It is a problem in boxing, although today's boxers and trainers know more about it and boxers have adopted a much more defensive style (lots of clinching, few face-to-face brawls) that prevents them getting punched in the head as much. See any recent Klitschko fight or the Mayweather - Pacquiao fight to see t... | [
"Aspiring boxers undergo years of apprenticeship, toughening their fists against stone and other hard surfaces, until they are able to break coconuts and rocks with their bare hands. Any part of the body may be targeted, except the groin, but the prime targets are the head and chest. Techniques incorporate punches,... |
If the US government printed $15 trillion to pay off the debt, what would the rate of inflation become? | Looking around, there are various estimates online of the total circulating US money supply, [this](_URL_0_) source estimates about $3.5 trillion in bills and coins, which would indicate the inflation caused by adding $15 trillion to the money supply should be around 500%. That's definitely just an order-of-magnitude ... | [
"In April 1979, however, the United States may have technically defaulted on $122 million in Treasury bills, which was less than 1% of U.S. debt. The Treasury Department characterized it as a delay rather than as a default, but it did have consequences for short-term interest rates, which jumped 0.6%. Others view i... |
How much ocean water is moved worldwide each tidal cycle? | I doubt anyone can answer that for the case of the Earth as it is far too complicated. Tides on the Earth are subject to the topography of the ocean bed and so vary throughout the oceans.
I think even for a homogeneous fluid body this might not be a straightforward question either. You can evaluate the tidal force thr... | [
"Long-Period tides are gravitational tides, typically with amplitudes of a few centimeters or less and periods longer than one day, generated by changes in the Earth's orientation relative to the Sun, Moon, and Jupiter. The distance between a reference point on the surface of the Earth relative to these objects can... |
what are the 165,000 new jobs the us economy says has been added in july and how are they created so quickly? | They are private-sector jobs.
However, some of them may have been spurred by the federal government's discretionary investments in the economy.
For example, let's say the Department of Transportation gave a hypothetical $1 million grant to build a bridge. The engineering plans for the bridge had already been approved... | [
"BULLET::::- January 4 – Government data reveals that the U.S. economy added 312,000 jobs in December, far ahead of predictions of 177,000, and that manufacturing ended 2018 with the most jobs added in one year since 1997.\n",
"BULLET::::- October 3 – The United States Department of Labor reports that in Septembe... |
How exactly did the Japanese worship their Emperor in the early 20th century/ww2? | To my knowledge the Emperor wasn't praised as a god via rituals as that would go against their religion to their many gods, it would have been seen as an insult.
In the early 20th century/WW2 era the Emporer was often thought to be a Demi-god or higher being, someone who has unquestionable reign over the entire nation... | [
"Like the rest of the country, the Japanese monarchy was changing too - but not in a way that made it resemble Western royalty. In the 1920s the Japanese were being taught that their emperor, living in a park in central Tokyo, was more than just a mere human being - he was called a living god. Children were educate... |
what do we measure in mhz when we are talking about cpus, does it have any moving parts like a hard-disk does? | A CPU is essentially made from switches. Tiny areas on a piece of silicon - a microchip - can be created such that they allow electricity to pass from one place to another when there is electricity supplied at a third point and not otherwise; or the inverse, they prevent electricity from passing through when there is e... | [
"66 (more specifically 66.667) megahertz (MHz) is a common divisor for the front side bus (FSB) speed, overall central processing unit (CPU) speed, and base bus speed. On a Core 2 CPU, and a Core 2 motherboard, the FSB is 1066 MHz (~16 × 66 MHz), the memory speed is usually 666.67 MHz (~10 × 66 MHz), and the proces... |
How did Nazi Germany a regime born out of the ruins of World War 1 have so much access to a diverse pool of top notch academics by world war 2? ( Rocket scientists, Gunsmiths, Cytologists/ciphers, Tank and aircraft engineers) | It seems to me that you assume that if there is hunger and some political chaos that all the institutions stop functioning? Germany before WWI was one of the most advanced countries on the planet, they won the most Nobel prices in the sciences up to that point. WWI was 4 years and after it was over the scientists or in... | [
"Politicization of the German academia under the National Socialist regime had driven many physicists, engineers, and mathematicians out of Germany as early as 1933. Those of Jewish heritage who did not leave were quickly purged from German institutions, further thinning the ranks of academia. The politicization of... |
you know that feeling when you're drinking something, and there's like a pause almost i'm not sure how to put it, a throat-cramp of sorts when it's going down your throat? sorry if nobody knows what i'm talking about | Yes. It hurts. I think it's an air bubble so there's not room for the liquid and the bubble so it feels like a trying to swallow big lump. | [
"Presents as a sensation of food getting stuck (dysphagia) in the mid- or lower esophagus, atypical chest pain, or cough. People often state they must drink liquids to swallow solid food. This motility problem results from atrophy of the gastrointestinal tract wall smooth muscle. This change may occur with or witho... |
Why are bronze and brass not as common metals to make things as they used to be in antiquity? | we have harder metals to work that produce a better product in the end.
The main issue with bronze is that its a rather soft metal and doesn't keep its edge well. While early iron suffered similar issues (with less reparability) the moment you start getting cast and later wrought iron plus steel you have a might sharp... | [
"In the 3rd millennium BCE ancient foundry workers discovered by trial and error that bronze had distinct advantages over pure copper for making artistic statuary. Bronze stays liquid longer when filling a mold due to its lower melting point. Bronze is a superior metal than copper for sculpture casting because of i... |
How do snipers/spotters calculate where to shoot? | From my Army experience, not as a sniper, but with basic rifle marksmanship training, I can tell you what I have learned. First, you learn to his a target at 300 meters. At this distance, you can learn to adjust the sights so when you shoot at the center of the target, you will hit the center of the target. There are a... | [
"Artillery spotters typically use their calibrated binoculars to walk fire onto a target. Here they know the approximate range to the target and so can read off the angle (+ quick calculation) to give the left/right corrections in meters.\n",
"When the trajectory of the bullet can be sensed, backtracking can be d... |
What's the correct response to this objection to special relativity? | Whoever wrote this is trying to discredit SR because they still hold onto the assumption of absolute time and don't understand that that assumption has to be abandoned. Let's take a look at this statement they make while talking about two clocks traveling at different speeds, they *completely* miss the point of SR.
>... | [
"Some criticized Special Relativity for various reasons, such as lack of empirical evidence, internal inconsistencies, rejection of mathematical physics \"per se\", or philosophical reasons. Although there still are critics of relativity outside the scientific mainstream, the overwhelming majority of scientists agr... |
how can energy companies guarantee a customer getting '100% green energy', when they also produce energy from fossil fuels? | Electricity isn't a physical object that's being piped around, so the idea of there being specific energy being produced in one place and then shipped around doesn't really work.
What the energy company is guaranteeing is that they'll supply, either by producing it themselves or buying it from another producer, enough... | [
"The Greens support the mass-rollout of renewable energy, with an aim of 100% renewable energy production by 2030, and phasing out the use of coal-fired power, as a means of driving investment and creating jobs. In 2019, the Greens pledged to create 180,000 new jobs in the renewable energy sector, including a renew... |
Do so-called "brain training" games really work? | I'm sure you'll get a lot of empirical articles here, and I encourage people to read them. However, here is the basic summation of what we know so far:
**"Brain training" activities improve performance on the specific activity you're training with. Most of those improvements, however, don't translate to improvements... | [
"Cognitive skills can be enhanced through repetition of puzzles, memory games, spatial abilities and attention control. Most video games present opportunities to use these skills with the ability to try multiple times even after failure. Many of these skills can be translated to reality and problem solving. This al... |
How is laze formed by lava mixing with sea water? | The high-temperature steam produced by the lava entering the ocean hydrolizes the various salts present in seawater, primarily chloride salts. This results in hydrogen from the steam combining with chloride ions, producing significant quantities of hydrogen chloride. As the steam recondenses it picks up this HCl to f... | [
"Pumice is created when super-heated, highly pressurized rock is violently ejected from a volcano. The unusual foamy configuration of pumice happens because of simultaneous rapid cooling and rapid depressurization. The depressurization creates bubbles by lowering the solubility of gases (including water and CO) tha... |
from where did country music emerge? | Hank Williams Sr. | [
"Country music is a genre of American popular music that originated in Southern United States, in Atlanta, Georgia in the 1920s, and It takes its roots from the southeastern genre of American folk music and Western music. The origins of country music are the folk music of mostly white, working-class Americans, who ... |
Why does the Dutch government reside in The Hague if the capital is Amsterdam ? | In 1248 William II, count of Holland and King of Germany started building a hall that's today known as the Ridderzaal. His son Count Floris V finished the construction in 1280. This is where the history of the Hague begins.
In the 14th century the Hague became the administrative capital of the county of Holland.
In ... | [
"The Hague is the seat of the Cabinet, the States General, the Supreme Court, and the Council of State of the Netherlands, but the city is not the constitutional capital of the Netherlands, which is Amsterdam. King Willem-Alexander lives in Huis ten Bosch and works at the Noordeinde Palace in The Hague, together wi... |
What exactly did the Jewish aristocracy do in Babylon? | As a corollary to OP's question:
What was the life of an average Jew in Babylon like? How were the classes divided? Were Jews well integrated into Babylonian society? | [
"Although most of the Jewish people during this period, especially the wealthy families, were to be found in Babylonia, the existence they led there, under the successive rulers of the Achaemenids, the Seleucids, the Parthians, and the Sassanians, was obscure and devoid of political influence. The poorest but most ... |
How true is the statement that the Soviet Union won the World War II in Europe? | There are two acceptable answers to this question. Militarily, the Soviet Union wins World War Two. They grind the Germans up, tie down major parts of the German army, and push gigantic distances (while taking serious casualties) to throw the Nazis back onto Berlin. The Russian steamroller tied down men, tanks, brillia... | [
"By the end of 1943 the tide of the war in Europe had shifted, and there was no doubt either about the survival of the USSR or the ultimate outcome of the Second World War. With the Red Army moving inexorably westward, the possibility of a Communist Europe seemed within reach to the party faithful. Cooperation betw... |
Okay, so I don't know anything about physics, but this question has been on my mind. | What you're looking for is called [Gravitational Lensing](_URL_2_)... and nothing can go faster than the speed of light (without funky quantum mechanical [jibber](_URL_1_) [jabber](_URL_0_)). | [
"\"Physics\" (from ) is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.\n",
"“What I liked about physics is tha... |
why toddlers are happy one moment then screaming and crying the next moment | One theory I have heard is that basically *everything* is a new experience for them, and they don't yet routines in place for dealing with things that seem trivial to adults.
Me: I dropped my pen. Drat. I will pick it up and then resume writing.
Toddler: I dropped my toy. FUCK! WHAT DO I DO? IT'S ALL SO INTENSE! | [
"Happy that they are save, they start laughing and mocking each other. The principal tells the parents that they are not worried about what happened and are happy. Feeling ashamed, the parents leave the children alone. \n",
"Beginning at birth, newborns have the capacity to signal generalized distress in response... |
Why was being able to flank an opponents army so powerful pre-gunpowder? | More can always be said, but the following previous answers are quite excellent explanations.
u/Iphikrates offers a [comprehensive treatment on just this topic here](_URL_0_), and u/theshadowdawn has a [similar answer here](_URL_1_), with special reference to the Battle of Cannae. | [
"Until the invention of gunpowder-based weapons (and the resulting higher-velocity projectiles), the balance of power and logistics definitely favored the defender. With the invention of gunpowder, cannon and mortars and howitzers (in modern times), the traditional methods of defense became less effective against a... |
why do so many animals like deer, boars, and tapirs all have dapple camouflage only when they are babies? why do they lose it when they grow older? | I think I’ve heard that the camouflage babies have only really works if they’re sitting completely still, which is fine because their parents will bring them food. But when they move, those spots become sort of a bulls eye, and they can’t afford to sit still anymore. | [
"Camouflage is a powerful influence in a large number of mammals, as it helps to conceal individuals from predators or prey. In arctic and subarctic mammals such as the arctic fox (\"Alopex lagopus\"), collared lemming (\"Dicrostonyx groenlandicus\"), stoat (\"Mustela erminea\"), and snowshoe hare (\"Lepus american... |
why do loud noises (e.g gun shots) trigger car alarms? | (10+ years selling/installing car security)
The part of the alarm that does this is called the "shock sensor". It's a little device that detects a "shock" to the vehicle via vibration.
The most common is a "504D" made by DEI. Feel free to search the part number if you'd like to see what it looks like/how it's install... | [
"Frequently, false alarms occur because car alarm owners use high sensitivity settings. This may be the main reason why loud bass frequency sound (loud music, other cars or motorcycles with loud exhaust systems, thunderstorms, etc.) can set off car alarms. The second possible reason is that some parts of the alarm ... |
how do people "live" in an embassy for extended periods of time? i've never visited an embassy, are they like hotels or something or it just a very awkward situation? | It really depends on the countries involved and the situation. A lot of embassies are nothing more than office buildings with no living accommodations.
The U.S. Embassy in London is an office building and the U.S. amabssador lives in a huge mansion called Winfield House in Regents Park. Most of the staff are locals an... | [
"A temporary resident is a foreign national granted the right to stay in a country for a certain length of time (e.g. with a visa or ), without full citizenship. This may be for study, business, or other reasons.\n",
"Though travelling to and from countries is generally permitted (with some limitations), most gov... |
how do soldiers in modern armies accurately direct artillery fire? | I had to learn artillery fire when I was a scout in the Army. Back then we didn't have GPS and our range finders never worked.
Before you go out, you and your artillery-men you are likely to be working with on the radio are given specific maps. On these maps are pre-designated areas with codes, you could use anything ... | [
"Artillery gunners are taught how to use direct fire to engage a target such as mounted or dismounted troops attacking them. In such a case, however, the artillery crews are able to see what they are shooting at. With indirect fire, in normal artillery missions, the crews manning the guns cannot see their target di... |
What was the role of light infantry in Napoleonic era battles? | So, first I'll unpack a few things. What I will be talking about is mainly focused on the French Imperial Army, I don't know enough of the other army compositions to help but I am sure that we have the right people to help. Second, within the French army, there is a difference between light infantry and skirmishers and... | [
"Light infantry sometimes carried lighter muskets than ordinary infantrymen while others carried rifles and wore rifle green uniforms. These became designated as \"rifle regiments\" in Britain and \"Jäger\" and \"Schützen\" (sharpshooter) regiments in German-speaking Europe. In France, during the Napoleonic Wars, l... |
why does so many people hate the baby boomer generation? | The current economic, political, and environmental climates were almost entirely influenced by members of that generation to where they are today.
The housing market, education costs, this team mentality for politics, climate, all are in pretty shitty shape for the next generation to deal with. Its also not super unco... | [
"This population is sometimes referred to as Generation Jones, and less commonly as Tweeners. These cuspers were not as financially successful as older Baby Boomers. They experienced a recession like many Generation Xers but had a much more difficult time finding jobs than Generation X did. While they learned to be... |
why does this paper shatter after being folded seven times with a hydraulic press? | Paper, when folded in half, effectively doubles its thickness. When folded six times in half, there is too much thickness and not enough surface area for anything to make an effective seventh fold.
However, the hydraulic press has enough force to fold it, but that puts extreme stress on the paper, which is eventually ... | [
"The Hydraulic Press Channel (HPC) is a YouTube channel operated by Finnish factory owner Lauri Vuohensilta and his wife Anni. Launched in October 2015, the channel publishes videos of various objects being crushed in a hydraulic press. On 31 October 2015, the channel published a video of Vuohensilta unsuccessfully... |
why can i usually smoothly fast forward a digital video (netflix, hbo go, dvds, etc) but reverse playback is always a jerky mess? | Vidoes general are usually buffered forwards not backwards. Basically they assume that once youve seen it already it's unlikely that you will go back to see it again.
So if you do have to go back all the currently buffered data is tossed out and then you are basically starting fresh from that new point that you jumpe... | [
"Analogue VCRs provided fast-forward by simply playing the tape faster. The resulting loss of synchronization of the video was accepted because it was still possible to make out approximately what was happening in the video to find the desired playback point. Modern digital video systems such as DVR and Video on De... |
Why are things from the past so far underground? In millions of years when our skeletons are where the dinosaurs skeletons are now, where did the old ground go? Where did the new ground come from? | If you drop dead right now and left your body to nature, you won't end up underground like fossils. Scavengers will pull you apart and eat you, you will rot and the rains and ravages of time will remove all traces of you. Even if you were buried at a funeral, you won't become a fossil.
The conditions needed for you to... | [
"Guy Darrough, a paleontologist from St. Louis, Missouri currently working at the dig site, said it was \"pretty much a miracle\" that dinosaur bones were found in Missouri, because the state's soft soil has resulted in the deterioration of most prehistoric remains. However, some of the remains found have been dama... |
Following the death of Augustus, why didn't he wish full power to go back to the Senete? | *EDIT: While I love the period, I'm not an expert, so please read /u/LegalAction's counterpoints below.*
There is an overly idealised fantasy, portrayed in for example the film Gladiator though it is not limited to Hollywood, of the Roman Republic as this freedom-loving democratic nation. It was not.
The Roman Republ... | [
"Augustus' final goal was to figure out a method to ensure an orderly succession. Under Augustus' constitution, the Senate and the People of Rome held the supreme power, and all of his special powers were granted for either a fixed term, or for life. Therefore, Augustus could not transfer his powers to a successor ... |
in what sense have creditors been "pillaging" greece for the past five years? | Greeks feel that the austerity measures imposed on Greece by it's creditors, which are enforced because the lenders feel they will make the greek economy more competitive and a more attractive target for investment, aren't actually helpful. They see austerity more as a punishment for the greek people, or at best a poor... | [
"It stands out in the history of sovereign defaults. Greek debt restructuring of 2012 achieved very large debt relief – with minimal financial disruption, using a combination of new legal techniques, exceptionally large cash incentives, and official sector pressure on key creditors. But it did so at a cost. The tim... |
Why were there so few violent border changes between the Christian Iberian kingdoms? | A reply to /u/HenkWaterlander ,
Maybe you can clarify what assertion you are questioning, because your wording is ambiguous. Are you suggesting that the Christian kingdoms of Iberia had very little among themselves *before* the Reconquesta? How do you determine "very little"?
Leon was united with Castile only after ... | [
"Ultimately, the Christian kingdoms in the north of the Iberian Peninsula overpowered the Muslim states to the south. In 1085, Alfonso VI captured Toledo, starting a gradual decline of Muslim power. With the fall of Córdoba in 1236, most of the south quickly fell under Christian rule and the Emirate of Granada beca... |
How are human skulls or other complex body structures posthumously extracted from a cadaver for use in museums or medical schools? | There are a combination of methods. One is maceration. Basically, it involves removing as much of the soft tissue as is practical, then allowing the rest to decompose under controlled conditions, often in temperature-controlled water, until the rest of the tissue is soft enough to be cleaned away. Another method can... | [
"Skulls Unlimited International, Inc. not only sources their specimens, they still also process the carcasses using the methods Jay perfected in his adolescence. This process begins with removing the majority of the soft tissue from the carcasses by hand. Then two methods are used to detail clean the skulls: dermes... |
how does the human body tend to itself when you havent eaten for days? what about havent drank? | There's a general rule of threes for your body's survival. 3 weeks without food, 3 days without water and 3 mins without air.
Without food, your body starts to consume its reserves. First to be consumed is the sugar reserve kept in your liver (about 500 grams). Then the body will try to breakdown the body's fat and mu... | [
"When the human body becomes dehydrated, it experiences thirst. This craving of fluids results in an instinctive need to drink. Thirst is regulated by the hypothalamus in response to subtle changes in the body's electrolyte levels, and also as a result of changes in the volume of blood circulating. The complete eli... |
if my car is on a steep downward incline and i put it into reverse gear, why does it roll backward up the hill even if i don't press the accelerator? | Because you put it in reverse gear. So long as the engine is producing enough power to move the car, and the clutch is capable of translating that much power without slipping, the car is going to move, otherwise the engine is just going to stall if it's not producing enough power. | [
"Pulling the car \"backward\" (hence the name) winds up an internal spiral spring; a flat spiral rather than a helical coil spring. When released, the car is propelled forward by the spring. When the spring has unwound and the car is moving, the motor is disengaged by a clutch or ratchet and the car then rolls free... |
please expain noam chomsky and his
views on the ideal type of governance li12 | I don't think Chomsky can be properly explained in the format of an ideal form of government (maybe he can, but it'd hurt the LI12-level of it all).
At the heart of Chomsky's political thought is the question of authority. Why does the government get to tell people what to do, and why should it be like this? He's said... | [
"In a 2011 interview with the Institute for Global Law and Policy at Harvard University, Parsi asserted that his thesis had \"been vindicated\" by recent events. \"I believe it is increasingly clear that efforts to divide the region between moderates vs radicals, democracies vs non-democracies etc is of little util... |
How, and why, do ants make new hills? | An "anthill" is just one extension of an ant hive that reaches the surface. The hills form when dirt is left by the entrance of the hills.
_URL_0_
Additionally, some species of ants have more than one queen per colony (polygyne), while others have one per colony (monogyne).
_URL_1_ | [
"Ant hill art is a growing collecting hobby. It involves pouring molten metal (typically non-toxic zinc or aluminum), plaster or cement down an ant colony mound acting as a mold and upon hardening, one excavates the resulting structure. In some cases, this involves a great deal of digging. The casts are often used ... |
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