question stringlengths 3 301 | answer stringlengths 9 26.1k | context list |
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Could airplanes save fuel by having support solar panels? | No. The added weight would counteract any (small) savings in fuel required. | [
"In the 1980s, new attention was focused on aircraft propelled by solar power. Solar photovoltaic (PV) cells, are not very efficient, and the amount of power provided by the Sun over a unit area is relatively modest. A solar-powered aircraft must be lightly built to allow low-powered electric motors to get it off t... |
why are un-cut diamonds illegal to have in some countries? | It's not illegal to have uncut diamonds, it is illegal to import conflict diamonds in most western countries however (it's very hard to get a hold of a real conflict diamond these days, especially if you buy them from a legitimate business). Those diamonds however are likely conflict diamonds that are illegal to import... | [
"The custom common in Africa, uncut diamonds tend to be the de facto standard currency of the illicit small arms trade. Diamonds may be easily counted with a uniform valuation per carat to people in places of the world where there are no automated teller machines. An entire briefcase filled with uncut diamonds with... |
how can a company like uhaul allow me to drive their trucks halfway across the country and leave them at different uhaul centers? wouldn't some centers lose more trucks than they take in and vice versa? | Yes, it happens just like you expect. Companies like U-haul and RV rental companies, etc. have programs to mitigate this - car transport, or RV companies will buy 1-way plane tickets for drivers to move their RVs for them. | [
"Two Men And A Truck is a franchised moving company, headquartered in Lansing, Michigan, with franchises in 43 U.S. states, as well as the United Kingdom, Canada, and Ireland. The company is the largest franchised moving company in the United States with more than 340 locations.\n",
"MHC operates 68 truck dealers... |
what does it mean when a video game is in pre-alpha/alpha/beta? | It means that the game is not done. Imagine you are building a house. You start with the foundation that might be called pre-alpha. You ave an idea of the shape of the house but it's not realy a house yet.
Then frame in the walls. Then you insulate it and put siding up. At this point it might be called an "alpha... | [
"\"Alpha\" is the stage when key gameplay functionality is implemented, and assets are partially finished. A game in alpha is \"feature complete\", that is, game is playable and contains all the major features. These features may be further revised based on testing and feedback. Additional small, new features may b... |
what is happening to the engine when i'm at high rpm's, but i haven't shifted yet? | The car has a sensor on the accelerator to determine how far it's pushed down. When you 'floor' it you generally want to accelerate fast. In order to do so you require high RPM and thus high power from the engine. So the gear shift is delayed in order to achieve the higher RPM. This is due to gear ratios within the tra... | [
"Engine RPM seemed to be more a function of accelerator pedal position than of actual road speed. \"Flooring\" the accelerator pedal would cause the engine speed to flare (even though there is no automatic downshift and no torque converter lockup to disengage). As the car would accelerate, RPM would further climb, ... |
why is marijuana detectable through urine drug tests for so long (at least 1 month for regular smokers typically) while other drugs (meth, cocaine, heroin, etc.) aren't detectable generally past 72 hours-a week at the most? | THC and many of it's derivates are fat-soluble, a characteristic that many other drugs do not have, and slows down the removal from the body. This is very similar to how some vitamins are dangerous in high amounts, while others can be taken in large quantities daily with few side effects. | [
"While there are blood, urine and hair tests that can track marijuana's active ingredient in the body, marijuana lingers around for too long a period in order for one of these tests to determine the actual intake time. Also, the variation between different metabolisms makes an objective cannabis intoxication test v... |
How is methane formed without biological activity? It seems to be very common from Jupiter to Pluto. | You don't need biological activity to form methane. On Earth, you don't see a lot of non-biological methane or industrial production because there's so much of it around already that there's no need to mass produce it. But the reaction of CO2 and H2 to form H20 and methane is exothermic. All you need is high temperatur... | [
"It was initially thought that methane is chemically unstable in an oxidizing atmosphere with UV radiation and so its lifetime in the Martian atmosphere should be about 400 years, but in 2014, it was concluded that the strong methane sinks are not subject to atmospheric oxidation, suggesting an efficient physical-c... |
What do we know about conditions on early earth? | Yay someone asked about my research area.
We know quite a bit about early earth actually. First off we have samples all the way back to 4.4 billion years ago. These samples come in the form of tiny minerals known as Zircons (ZrSiO4). These are incredibly hard minerals that survive lots of heating so they are perfect. ... | [
"The geological record however shows a continuous relatively warm surface during the complete early temperature record of Earth – with the exception of one cold glacial phase about 2.4 billion years ago. In the late Archean Eon an oxygen-containing atmosphere began to develop, apparently produced by photosynthesizi... |
when installing a computer program, why does the last 1% often take longer than the previous 99%? | Because time/progress indicators are a remarkably hard problem which has little payoff for getting right. There isn't an obvious way to get the indicator right as each step in the process contains diverse sub steps that are often not compatible with each other (writing to the file system vs checking a remote site for u... | [
"In Ninety-ninety rule, Tom Cargill is credited with this explanation as to why programming projects often run late: \"The first 90% of the code accounts for the first 90% of the development time. The remaining 10% of the code accounts for the other 90% of the development time.\" Any guidance which can redress this... |
Roman Marching Camps | For the most part these camps were made of easily portable materials. The camps were just a few tents surrounded by a wooden palisade. These materials were usually packed away and taken with the unit as they marched. The Limes or border forts and outposts were more permanent, usually made out of heavy stone. One such e... | [
"At the end of a day's march, the Romans would typically establish a strong field camp called a castra, complete with palisade and a deep ditch, providing a basis for supply storage, troop marshalling and defence. Streets were laid out, units designated to take specific places, and guards posted at carefully design... |
what factors differentiate a crime of passion from a premeditated crime? | It's a grey area. The concept doesn't exist in all jurisdictions.
I believe that you have to establish that the person was so effected that they were driven to irrational behaviour that was out of character for them.
If the woman had no history of violence and stabbed the cheating husband a week later (after slowly b... | [
"A crime of passion (French: crime passionnel), in popular usage, refers to a violent crime, especially homicide, in which the perpetrator commits the act against someone because of sudden strong impulse such as sudden rage rather than as a premeditated crime.\n",
"The 'crime of passion' defense challenges the \"... |
Why didn't everyone attend higher education during American colonial times? Was it just something children of elites did? | It's best to think of higher education during the colonial era more like secondary school than college as we think of it today. One could almost think of them as akin to (but not exactly like) boarding schools for white boys from families of means. In 1810, the average age at a colony college was 15 and all of those st... | [
"an unusual privilege for a country boy of that time. Few people of the colonial era were formally educated, mostly due to cost and lack of inexpensive public schooling. Education of any formal sort in colonial New England carried a significant degree of elite social status.\n",
"During the period of British Colo... |
Why were there such erratic changes in climate during the Little Ice Age, and why did it stop? | I think it would be hard to give a solid answer. A number of things (constructive/destructive interference of orbital cycles, insolation levels, positive feedback through glaciation, adjustment of moisture pathways, etc) likely played into the LIA which determined its duration and intensity. Furthermore, climate proxi... | [
"Most abrupt climate shifts, are likely due to sudden circulation shifts, analogous to a flood cutting a new river channel. The best-known examples are the several dozen shutdowns of the North Atlantic Ocean's Meridional Overturning Circulation during the last ice age, affecting climate worldwide.\n",
"Between ro... |
what is the difference between positive and negative g-force? | Direction.
Normally you feel a force of +1g, pushing you straight down.
If you were in an elevator accelerating upwards which, you might experience a force of +2g. And if the elevator was accelerating downwards very quickly, you might actually feel an upwards force of -0.5g. That's what a negative g-force is, when ... | [
"Negative G-force (pressure of the blood towards the head) is much more beneficial to the body than positive G-force (the blood runs toward the feet). Negative G-forces can be reached during bungee jumps during approximately a second when the jump is over a hundred meters high. These are less severe strains than th... |
Do images taken by Hubble Telescope have the same colors that we see? | The Hubble Telescope works somewhat similarly to how the human eye works.
The human eye sees colour by having three different types of light sensor. Each of these is sensitive to a different range of wavelengths of light. But combining the three sets of signals from the three different types of light sensors, you get ... | [
"The Hubble Space Telescope image produced here is in false colour, designed to highlight regions of high and low ionisation. Three images were taken, in filters isolating the light emitted by singly ionised hydrogen at 656.3 nm, singly ionised nitrogen at 658.4 nm and doubly ionised oxygen at 500.7 nm. The images ... |
[Quantum Mechanics] How does the true randomness nature of quantum particles affect the macroscopic world ? | Not sure if this answers your question, but one example that comes to mind is nuclear decay. Quantum effects dictate when any specific radioactive isotope decays and yet the effect is powerful enough to affect the macroscopic world. For example, a single decay at the right time and place could, and probably has at so... | [
"According to several standard interpretations of quantum mechanics, microscopic phenomena are objectively random. That is, in an experiment that controls all causally relevant parameters, some aspects of the outcome still vary randomly. For example, if a single unstable atom is placed in a controlled environment, ... |
What are the chances of touching the same water molecules in two different locations during two different parts of your life? | Very high.
A common high school chemistry/physics problem is to compute the odds that one of the molecules you inhale next would have been part of Caesar's dying breath. Depending on your assumptions, it usually works to 90-95%.
When you consider that water is much denser, and that you are compare all the water you ... | [
"It is (in principle) easy to measure whether or not two regions (for example, two glasses of water) have the same electrochemical potential for a certain chemical species (for example, a solute molecule): Allow the species to freely move back and forth between the two regions (for example, connect them with a semi... |
what causes clouds to form or congregate around mountains? | Wind pushes air into the side of the mountain. Where can it go? Some air goes around but some is forced upward. The air going up reduces in pressure with the altitude, expands, and cools. This reduces the amount of water vapor it can hold and often results in it condensing to form clouds. | [
"On Earth, mountain ranges sometimes force an air mass to rise and cool down. As a result, water vapor becomes saturated and clouds are formed during the lifting process. On Mars, orbiters have observed a seasonally recurrent formation of huge water-ice clouds around the downwind side of the 20 km-high volcanoes Ar... |
We all know of people defecting from the Soviet Union to America, but did any Americans defect to the Soviet Union? | Read "The Forsaken" by Tim Tzouliadis. It's about a group of American workers who moved to Stalin's USSR during the depression with the hope of finding a workers' paradise. Incredibly sad and tragic what happened to them.
Also, Kim Philby was one of the most famous defectors - he was British not American, but it's a... | [
"During the Cold War, the many people illegally emigrating from the Soviet Union or Eastern Bloc to the West were called defectors. Westerners defected to the Eastern Bloc as well, often to avoid prosecution as spies. Some of the more famous cases were British spy Kim Philby, who defected to Russia to avoid exposur... |
If Ancient Carthage was raised to the ground by the Romans, how accurate is our historical insight of the people/culture/way of life when all we have to go off are biased Roman accounts? | Razed.
Anyway, Carthage isn't that difficult to learn about. Carthage was settled by Phoenicians, who lived in the general vicinity of modern Lebanon. They had smaller settlements in modern neighboring countries, but they generally lived on the Lebanese coast -- cities like Sidon, Tyre, and Byblos. They are, respecti... | [
"In the end, however, most Punic writings that survived the destruction of Carthage \"did not escape the immense wreckage in which so many of Antiquity's literary works perished.\" Accordingly, the long and continuous interactions between Punic citizens of Carthage and the Berber communities that surrounded the cit... |
how do you advance ranks in the military? | Air Force Reserve Officer here. You're asking a pretty broad question. I'm not sure how it works for enlisted or other branches, but officers in the AF Reserves: O1 to O3 are "time in service" meaning they're automatic. To transition from company grade to field grade officer, you need to go to Squadron Officer School. ... | [
"Promotion to the rank of sergeant and beyond is achieved by way of a \"merit based\" promotion system, whereby officers undertake a series of \"pre-qualification assessments\" and are placed on a ranked list before gaining promotion. Officers who qualify for a promotion list are given an eligibility mark and are r... |
Are there any European families that still exist today that can trace their origins to the aristocracy/patrician families of the Roman Empire? | They can't document it (and it seems a common enough root to derive a name from) but the Massimo family at least makes the claim.
_URL_0_
> When asked by Napoleon (with whom he was negotiating the Treaty of Tolentino) whether the family descended from Fabius Maximus, the then Prince Massimo famously replied "I do n... | [
"Many of the ancient patrician gentes whose members appear in the founding legends of Rome disappeared as Rome acquired its empire, and new plebeian families rose to prominence. A number of patrician families such as the Horatii, Lucretii, Verginii and Menenii rarely appear in positions of importance during the lat... |
When we look at developing galaxies that are millions of light years away, can scientists assume the current appearance? | Well something a million light years away would look just about the same now as it does in the picture, because a million years is a really short time astronomically.
If it was something many billions of light years away, then it would be nigh impossible to predict what a given galaxy would look like today, because w... | [
"Scientists hope to find older galaxies; however, closer to the Big Bang, fewer exist and they are dimmer on average. They will therefore be increasingly difficult to find, since they would be very faint with fewer observable stars. Trenti says that new \"most distant\" record holders will soon be announced, but on... |
When did the use of a "Bra" become a social standard? | Not quite the same question, but I think you'll find this pretty relevant:
_URL_0_ | [
"Some feminists began arguing in the 1960s and 1970s that the bra was an example of how women's clothing shaped and even deformed women's bodies to male expectations. Professor Lisa Jardine listened to feminist Germaine Greer talk about bras during a formal college dinner in Newnham College, Cambridge, in 1964 (Gre... |
How much does the resting/basal metabolic rate vary between individuals with similar body composition and weight? | In short, yes. I can't find the study right now, but basically it took a group of people and had them sit around in an airtight room all day, then measure how CO2 they gave off. From this they calculated the individuals BMR. I believe the two biggest factors that influenced were sex and age (unsurprisingly). The third ... | [
"Basal metabolic rate (BMR) is the rate of energy expenditure per unit time by endothermic animals at rest. It is reported in energy units per unit time ranging from watt (joule/second) to ml O/min or joule per hour per kg body mass J/(h·kg). Proper measurement requires a strict set of criteria be met. These criter... |
why do cars take forever to heat up, when my space heater is instant? why don't we use "regular" heaters in cars? | Your car's heater uses waste heat from the engine's cooling system. The benefit is that that heat is "free" (it's a byproduct of combustion). The downside is that it takes a while, since your engine block is a big hunk of metal. An electric space heater consumes a lot of watts--it would be difficult and costly to achie... | [
"Space heating for residential and commercial applications can be done through the use of solar air heating panels. This configuration operates by drawing air from the building envelope or from the outdoor environment and passing it through the collector where the air warms via conduction from the absorber and is t... |
Every form of Christianity has retranslated the bible to better suit their beliefs and language. There are no surviving original manuscripts. How accurate are modern translations to the original text and what nuances in language have been omitted, and what text has been added? | > How accurate are modern bibles like the New King James Version to the original aramaic?
One nitpick--a relatively small portion of the bible is in Aramaic. The Hebrew bible is almost all Hebrew, and the New Testament is entirely Greek (with a few Aramaic words and phrases thrown in).
This question is not quite an... | [
"The New Testament has been preserved in more than 5,800 fragmentary Greek manuscripts, 10,000 Latin manuscripts and 9,300 manuscripts in various other ancient languages including Syriac, Slavic, Ethiopic and Armenian. Not all biblical manuscripts come from orthodox Christian writers. For example, the Gnostic writi... |
what is the "quantum" in quantum physics, quantum computers and so on? | Go and grab a magnifying lens and look at your monitor, can you see the little squares composing it? That's a pixel. It's a quantum of image.
If you look at a picture on your screen, the image will be created putting these little pixel-tiles one close the the other. It seems smooth, but if you look close enough and se... | [
"A quantum computer is a computation system that makes direct use of quantum-mechanical phenomena, such as superposition and entanglement, to perform operations on data. Quantum computers are different from digital computers based on transistors. Whereas digital computers require data to be encoded into binary digi... |
Question about LCDs | Most modern LCDs are backlit, they have an LED or compact fluorescent light source behind the LCD panel which provides illumination. Without this the LCD would be very dark and difficult to see. When the monitor is off the backlight is off. | [
"LCDs are used in a wide range of applications, including LCD televisions, computer monitors, instrument panels, aircraft cockpit displays, and indoor and outdoor signage. Small LCD screens are common in portable consumer devices such as digital cameras, watches, calculators, and mobile telephones, including smartp... |
Can anyone help identify this? I've had it for a few years. (German certificate of some sort 1935) | You can try r/translator for this. | [
"An image of Clara Schumann, from an 1835 lithograph by Andreas Staub, was featured on the 100 Deutsche Mark banknote from 2 January 1989 until the adoption of the euro, on 1 January 2002. The back of the banknote shows a grand piano she played, and the exterior of the Hoch Conservatory, where she taught. The great... |
why is icelandic considered a separate language and not old norwegian? | Because the spelling, phonology and grammar have changed quite significantly, even if an icelandic speaker can with a small amount of effort understand old norse.
Also, because it is a language spoken by icelanders in iceland. As the mainland languages started diverging the need to signifiy the uniqueness of Iceland... | [
"In contrast to Old Norse, Modern Norwegian has simplified inflections and a more fixed syntax. Old Norse vocabulary is to a considerable degree substituted by Low German, and this is the main reason why Modern Norwegian, together with contemporary Norwegian in general, Danish and Swedish, is no longer mutually int... |
why are car navigation and voice controls so clunky when we have the technology in phones to be very smooth? | Siri and all those like it ship the audio off your phone to a server at Apple/Google/wherever to do the speech to text processing. They have huge farms of optimized servers for that. Your in-dash navigation system has to do it all itself with a relatively slow processor. | [
"As car technology improves, more features will be added to cars and these features will most likely distract a driver. Voice commands for cars, according to CNET, should allow a driver to issue commands and not be distracted. CNET states that Nuance is suggesting that in the future they will create a software that... |
what number do banks use to calculate interest? | You get interest based on how much is in your account at the end of each day.
If you have $0 in the account at the end of each day, you get zero.
If you have $500 every day (say you left it alone the whole month), you get $500 * interest rate.
If you moved money in and out, and you averaged $300 per day, they pay yo... | [
"Suppose a principal amount of $1,500 is deposited in a bank paying an annual interest rate of 4.3%, compounded quarterly.br Then the balance after 6 years is found by using the formula above, with \"P\" = 1500, \"r\" = 0.043 (4.3%), \"n\" = 4, and \"t\" = 6:\n",
"If the interest is credited twice in the year, th... |
How can our bowels selectively pass either gaseous or solid/liquid contents? | To move fecal matter you use persistaltic muscle contractions in your intestines, for gas these movements are either minimized or not present-releasing gas compared to a solid is much easier. The body has many sphincters, which is something that just constricts an opening. For a sphincter to pass gas it doesn't need to... | [
"Bowel obstruction may be complicated by dehydration and electrolyte abnormalities due to vomiting; respiratory compromise from pressure on the diaphragm by a distended abdomen, or aspiration of vomitus; bowel ischemia or perforation from prolonged distension or pressure from a foreign body.\n",
"Volvulus occurs ... |
how can usps not insure all their packages? if the package is lost-in-transit, they've taken money from you for a service that they didn't provide, and then don't refund you the value of the product or even the value of the service?! | No it's not illegal. It's incumbent upon you to insure it if it has any value. Once it's insured, it can't be lost, because extra steps are taken to make sure it doesn't get lost. Plus, you get a tracking # so it can be tracked and located. If it's insured, the carrier knows that he is personally responsible for that i... | [
"Users can sell clothing, shoes and handbags in two ways: request a prepaid selling kit or print out a shipping label. Twice processes the items and sends an all-or-nothing offer to the user within days, which users accept or reject. If accepted, Twice offers multiple options for immediate payout including PayPal a... |
could you expose newborns to math to make them learn naturally like language? | We do that! Most babies start learning to count at the same age as they start learning to speak.
Could we teach algebra and trigonometry at that age? No. Maths, far more than languages, is a progression of different techniques. In the very early years, where babies learn without even trying, they will be able to learn... | [
"Hyperlexic children are often fascinated by letters or numbers. They are extremely good at decoding language and thus often become very early readers. Some hyperlexic children learn to spell long words (such as \"elephant\") before they are two years old and learn to read whole sentences before they turn three.\n"... |
How true is this comment? Was Hitler in any way "progressive"? | I am not trying to stifle further discussion, but a [search for "hitler socialism"](_URL_0_) returns many discussions about the ideological orientation of National Socialism in Germany. | [
"In \"Mein Kampf\", Hitler talks of the success of British propaganda in World War I, believing people's ignorance meant simple repetition and an appeal to feelings over reason would suffice. Hitler chose Riefenstahl as he wanted the film as \"artistically satisfying\" as possible to appeal to a non-political audie... |
Is there any connection between Gothic Architecture and Goths (Visigoths or Ostrogoths)? | Yes, but the connection is more linguistic than practical. 'Gothic' as a term originated as a pejorative description of a supposedly barbarous artistic style. 'Gothic' is one of the words art historians attach to a certain style in order to better classify and compartmentalise.
The Gothic style itself was a product o... | [
"Originating in semi-legendary Scandza (believed to be somewhere in modern Götaland, Sweden), a Gothic population had crossed the Baltic Sea before the 2nd century AD. They reaching Scythia on the coast of the Black Sea in modern Ukraine, where Goths left their archaeological traces in the Chernyakhov culture. In t... |
How do electronic devices limit how much power they get from a wall socket? | They limit it by the resistance. The grid guarantees you two things
-a certain frequecy (50Hz or 60Hz usually)
-a certain voltage (110, 220, 230, 380, 400V are the usual voltages)
the current it gets is then limited by its resistance | [
"BULLET::::- As the charging socket shares a feeder from the switchboard with other sockets (no dedicated circuit) if the sum of consumptions exceeds the protection limit (in general 16 A), the circuit-breaker will trip, stopping the charging.\n",
"High-voltage electrical equipment (generally regarded as being ov... |
How did the Romans go about demolishing buildings as well as other large man-made structures- particularly as they razed cities? | A couple of things: if you think that Scipio Africanus "salted the earth" of Carthage, he didn't. It's been a persistent myth from the 19th century, but Polybius and other ancient sources make no mention of it whatsoever. It may be based on the destruction of Shechem in the Book of Judges.
But, regarding the demoliti... | [
"When buildings reach the end of their useful life, they are typically demolished and hauled to landfills. Building implosions or ‘wrecking-ball’ style demolitions are relatively inexpensive and offer a quick method of clearing sites for new structures. On the other hand, these methods create substantial amounts of... |
Why did the Mongols decide to attack the Hakata Bay area during their attempted invasions of Japan in 1274 and 1281? | Though it would be definitely better to wait for responses either from the Mongol History or Japanese Medieval Historians, I just complement some brief historical background around two Mongol invasion attempts as well as some facts on the Japanese-Chinese(-Korean) sea trade across the East China Sea in the 13th century... | [
"The Japanese defenders recognized the possibility of a renewed invasion and began construction of a great stone barrier around Hakata Bay in 1276. Completed in 1277, this wall stretched for 20 kilometers around the border of the bay. It would later serve as a strong defensive point against the Mongols. The Mongols... |
how and why does a word like 'bi-monthly' exist as it does? it simultaneously means twice a month and once every two months, which is an incredibly important distinction. | Bi- as a prefix usually means every two (as in bicentennial=200 years), but using it as "twice per" seems to have crept into usage as a malapropism. The more correct and less confusing way of saying "twice a month" is "semimonthly". The error might arise because "bi-" can also be used to denote "a pair of" like bipedal... | [
"Bimonthly is an ambiguous term for frequency, meaning either \"two times every month\" or \"every two months\". In publishing, \"every two months\" is the most common usage. The term \"semimonthly\" can be a substitute for the former meaning. French, for instance, has no confusion, with \"bimensuel\" the adjective... |
what is the difference between a dj and someone who plays music from their computer at a venue? | A DJ generally mixes the songs together so that they sound like one continuous song. It's a much harder job. | [
"DJ software can be used to mix audio files on the computer instead of a separate hardware mixer. When mixing on a computer, DJs often use a DJ controller device that mimics the layout of two turntables plus a DJ mixer to control the software rather than the computer keyboard & touchpad on a laptop, or the touchscr... |
why won't a stack of office paper burn like a hardwood log does in the fire pit? | Basically, carbon ash is a really good insulator and oxygen barrier. The outside of the paper stack will burn, but the core can't get any oxygen underneath the ash, and is fairly well thermally insulated until you poke it with a stick. | [
"BULLET::::- Charcoal was often manufactured nearby from locally available trees, but the heating retorts were typically separated from the other buildings to minimize fire danger. Trees with low value as sources of lumber were debarked, dried, and cut to uniform length to fit into iron retorts with cast iron doors... |
Is it possible to make a magnetic alloy from nonferrous metals or semiconductors? | Of the pure elements, **iron** (ferrum) is the best-known magnetic metal, of course. It's so prototypical that 'ferromagnetism', the best-known kind of magnetism, is named after it
*Ferrous metals* also are sometimes considered to include **nickel** and **cobalt** in addition to iron. All of them are highly ferromagne... | [
"While many traditional magnetic materials, such as magnetite, are also semiconductors (magnetite is a semimetal semiconductor with bandgap 0.14 eV), materials scientists generally predict that magnetic semiconductors will only find widespread use if they are similar to well-developed semiconductor materials. To th... |
why do blue led holiday lights appear purple in reflections? | Lots of paints and papers include fluorescent compounds. These are made to absorb UV light and output visible light to make the surface look brighter, but many of them are also activated by blue light. These fluorescent compounds are absorbing some of the blue and producing red and green light. | [
"White LEDs can be used as white holiday lights or to create any other color through the use of colored refractors and lenses similar to those used with incandescent bulbs. Color fading may occur due to the exposure of colored plastics to sunlight or heat, as with ordinary holiday lights. Yellowing may also occur i... |
what is the bad feeling you get but cannot figure out what you did that makes you uneasy? | When i was young i went to the beach with my parents every so often. But this one time i was swimming out a bit too far. Before i knew it the current was taking me and my beach ball to open sea. In my struggle to get back i had to ditch the ball and my mother and a bunch of strangers had to pull me out of the water. T... | [
"Negative moods, such as anxiety, often lead individuals to misinterpret physical symptoms. According to Jerry Suls, a professor at the University of Iowa, people who are depressed and anxious tend to be in rumination. However, although an individual's affective states can influence the somatic changes, these indiv... |
Is there tolerance differentiation between alcohol types? | I am pretty sure that all "alcohol" contains the same molecules that make you feel "drunk". The molecule is C2H5OH (ethanol) and all drinking alcohol contains this.
Now, during fermentation and distillation, some small quantities of other alcohols are produced, but generally everything is done to minimise these as the... | [
"Higher body masses and the prevalence of high levels of alcohol dehydrogenase in an individual increase alcohol tolerance, and both adult weight and enzymes vary with ethnicity. Not all differences in tolerance can be traced to biochemistry however. Differences in tolerance levels are also influenced by socio-econ... |
Who are some scientists that were traditionally considered to be outsiders by the scientific community? | Sorry, we don't allow ["example seeking" questions](_URL_1_). It's not that your question was bad; it's that these kinds of questions tend to produce threads that are collections of disjointed, partial, inadequate responses. If you have a question about a specific historical event, period, or person, feel free to rewri... | [
"Margaret Wertheim profiled many \"outsider scientists\" in her book \"Physics on the Fringe\", who receive little or no attention from professional scientists. She describes all of them as trying to make sense of the world using the scientific method, but in the face of not being able to understand the complex the... |
Can there be a lower limit to how much energy a given computational task (like encoding a video) can consume? | Yes, this is known as [Landauer's principle](_URL_0_)
Quoting wiki: "[Launder's principle] holds that any logically irreversible manipulation of information, such as the erasure of a bit or the merging of two computation paths, must be accompanied by a corresponding entropy increase in non-information-bearing degrees ... | [
"BULLET::::- The computational capacity of a $4,000 computing device (in 1999 dollars) is approximately equal to the computational capability of the human brain (20 quadrillion calculations per second).\n",
"Peak Performance: If the entry demonstrates outstanding performance in terms of floating point operations ... |
can someone explain how drug control rooms help drug addicts? | How do they help addicts?
They provide a safe environment, usually with clean needles, in which to use. There's medical attention nearby in case of OD. Most importantly, it's an environment where users can be exposed to *help,* where they can ask for help, where they won't be arrested or judged. | [
"Because people with a substance addiction are highly reactive to environmental cues previously associated with drug use, a common treatment strategy is to advise them to avoid people and situations formerly associated with drug use. For example, a smoker attempting to quit should avoid other smokers and places whe... |
if the image of a planet that is "x" million light years aways is also "x" million years old, how can we determine whether or not that planet contains life at the present? | You can't as a matter of principle because information can't be communicated faster than the speed of light. The only thing you might be able to do is determine whether life existed at the time the light you're seeing left the planet.
Edit: stupid typo | [
"By taking two exposures of the same section of the sky days or weeks apart, it is possible to find objects such as asteroids, meteors, comets, variable stars, novae, and even unknown planets. By comparing the pair of images, using a device such as a blink comparator, astronomers are able to find objects that moved... |
What are the powerful "classics" of history? | For antiquity, I'd suggest adding Caesar's *Commentarii de Bello Gallico* and Herodotus' *Histories.*
Thucydides is famed for his attempt at methodological thoroughness, attempts at even-handedness, use of eyewitnesses and chronological detail. But frankly, as language goes, you won't find the kind of inspiration ther... | [
"The first known use of \"classic\" in this sense — a work so excellent that it is on the level of the \"classics\" (Greek and Latin authors) — is by the 18th-century scholar Rev. John Bowle. He applied the term to \"Don Quixote\", of which Bowle prepared an innovative edition, such as he judged that a classic work... |
why do large, established companies like coca-cola outsource their branding to boutique firms? | Advertising is something that is generally outsourced to companies who specialize in it. It is very specialized, they are the experts at it, and they are the ones who do it. Sometimes they will keep some of the analytics in house, but generally at a minimum the creative and such is outsourced to the "experts" (but the... | [
"Corporations often rebrand in order to respond to external and/or internal issues. Firms commonly have rebranding cycles in order to stay current with the times or set themselves ahead of the competition. Companies also utilize rebranding as an effective marketing tool to hide malpractices of the past, thereby she... |
why laptop screens or monitors almost always have clouding or light bleed on the edges while smartphones screen don't | Most computer screens take advantage of LCD technology, which have a backlight and liquid crystals. The backlight is the lightsource, and the liquid crystals make up the pixels. Each pixel is basically a mini electric circuit, and depending on the voltage you can change the amount of light that can pass through. If you... | [
"Because of the reflective nature of the display, in most lighting conditions that include direct light sources facing the screen, glossy displays create reflections, which can be distracting to the user of the computer. This can be especially distracting to users working in an environment where the position of lig... |
What was the pinnacle of Native North American boating technology - is there any history of larger, long-distance watercrafts used for cargo or transportation, or even naval warfare? | Birch and spruce root canoes from the Great Lakes held some serious cargo. I've previously heard they could carry 1800 pounds but [William Ashworth](_URL_4_) writes they could be 40 feet long and carry several tons of cargo.
Dugout canoes made from single trunks were popular in the southeast. A cache of [101 precontac... | [
"In the time before ancient maritime history, the first boats are presumed to have been dugout canoes, developed independently by various stone age populations, and used for coastal fishing and travel. The Indigenous of the Pacific Northwest are very skilled at crafting wood. Best known for totem poles up to tall, ... |
ferrofluid is really cool, but what exactly are the possible applications? | To talk about applications we need to first talk about what a ferrofluid actually is.
Ferrofluids are just liquids with magnetic particles spread evenly in them, that together become magnetized when you place a magnet near them.
Generally this means that you can use a magnet to move or otherwise influence the liquid ... | [
"Ferrofluids can also be used in semi-active dampers in mechanical and aerospace applications. While passive dampers are generally bulkier and designed for a particular vibration source in mind, active dampers consume more power. Ferrofluid based dampers solve both of these issues and are becoming popular in the he... |
I heard that some of the first radios used crystals to 'receive' radio waves. How does this work, and are newer radios operating along the same principle? | The “crystal” used in early radios is not the same device as a modern quartz crystal used for frequency generation. The old crystals basically served as rectifiers (diodes) and were pretty effective at demodulating AM signals, converting them straight from RF to audio.
Modern radios use more complex circuitry, alt... | [
"A crystal radio receiver, also called a crystal set, is a simple radio receiver, popular in the early days of radio. It uses only the power of the received radio signal to produce sound, needing no external power. It is named for its most important component, a crystal detector, originally made from a piece of cry... |
why are glasses 'bad' for my eyes, and contacts 'good'? | No.
Usually, if anything, contacts are more likely to be "bad" for your eyes, in that they can lead to infections / eye drying out with poor habits/use.
With proper use, neither is better/worse. | [
"There have also been concerns over potential eye pain caused by users new to Glass. These concerns were validated by Google's optometry advisor Dr. Eli Peli of Harvard, though he later partly backtracked due to the controversy which ensued from his remarks.\n",
"People choose to wear contact lenses for many reas... |
why do people have a hard time pronouncing sounds from a new language, even though their vocal chords are capable of making that sound? | Producing a sound primarily has to do with muscle control and memory with the various surfaces of your mouth, not so much your vocal chords. You have problems pronouncing sounds in a new language because your mouth is not used to moving in that manner and you have to train it how to make those shapes correctly. Very li... | [
"This tendency to avoid consonant clusters in some positions is important when words are imported from English or other non-Bantu languages. An example from Chewa: the word \"school\", borrowed from English, and then transformed to fit the sound patterns of this language, is \"sukulu\". That is, \"sk-\" has been br... |
Can messages be broadcasted through "visible light" similarly to radio waves? | This exact message is being broadcast through visible light to your eyes. | [
"In order to transmit information, the continuous wave must be turned off and on with a telegraph key to produce the different length pulses, \"dots\" and \"dashes\", that spell out text messages in Morse code, so a \"continuous wave\" radiotelegraphy signal consists of pulses of sine waves with a constant amplitud... |
how does blitzkrieg attack work? what makes it special and recognizable to this day? | It literally means "lightning war". Basically, the Germans threw a ton of forces in one direction extremely fast when the enemy wasn't expecting it and didn't have time to respond.
This type of war strategy is effective if done right because it lets your forces secure key positions/territory that they need, overwhelm ... | [
"Blitzkrieg (, from \"Blitz\" [\"lightning\"] + \"Krieg\" [\"war\"]) is a method of warfare whereby an attacking force, spearheaded by a dense concentration of armoured and motorised or mechanised infantry formations with close air support, breaks through the opponent's line of defence by short, fast, powerful atta... |
State of the art in cancer research? | Have you read [The Hallmarks of Cancer](_URL_1_) (pdf) and the 2011 [update](_URL_0_)? These are basically must-read papers for understanding the molecular basis of cancer. For other people that want to learn more, but don't want to read a dense review article, the [wikipedia page](_URL_2_) for the paper gives a good... | [
"BULLET::::- publishing reports on several key areas of cancer research, including prostate cancer, lung cancer, radiotherapy, palliative care and prevention, many of which have led onto the establishment of specific initiatives to fund aspects of research in these fields where a strategic gap was identified.\n",
... |
Do germs have a circadian rhythm? | Germs are simple bacteria and viruses which don’t have a nervous system. without a nervous system you can’t have a circadian rhythm.
bacteria and viruses don’t sleep or rest. they just kind of exist and move around taking in nutrients to divide. viruses definitely don’t rest or sleep because they aren’t even alive. | [
"Circadian rhythms have been discovered in a diversity of organisms. These rhythms control a variety of physiological activities and help organisms to adapt to environmental conditions. Cyanobacteria are the most primitive organisms that demonstrate a circadian oscillation. Cyanobacteria clocks were first founded i... |
why doesn't the military allow steroid use? wouldn't they make them better soldiers physically? | You don't want a bunch of hormone filled, angry, jealous, pimple faced soldiers carrying guns and manning drones... | [
"Some medical authorities criticized this drug regimen, with distributed pills numbered in the millions, as having the negative consequence that many soldiers became addicted to drugs and useless in any military capacity, whether combat or supporting.\n",
"Enhancing substances (steroids) are sometimes used in the... |
Will someone please explain the origins of avian species. | Wings have evolved exactly four times in the history of life. First was insects. Second was pterosaurs, which are now extinct. Third time was birds. And the fourth time was bats.
Wings all seem to have evolved from species that spent a lot of time jumping through the air. They could be used to control direction o... | [
"Other studies have proposed alternative phylogenies, in which certain groups of dinosaurs usually considered non-avian may have evolved from avian ancestors. For example, a 2002 analysis found that oviraptorosaurs were basal avians. Alvarezsaurids, known from Asia and the Americas, have been variously classified a... |
Is hydraulic fracturing and shale gas really harmful to the environment? How would it compare to other energy sources including all steps from extraction to consumption? | It depends on a lot of factors. Fracing itself isn't dangerous, but if placed near a valuable groundwater source it is. Even then it depends very highly on the nature of the natural gas itself.
Its best to think of the problem from an environmental engineer's perspective - source, pathway, receptor. These three ele... | [
"The potential environmental impacts of hydraulic fracturing include air emissions and climate change, high water consumption, groundwater contamination, land use, risk of earthquakes, noise pollution, and health effects on humans. Air emissions are primarily methane that escapes from wells, along with industrial e... |
why is camilla the duchess of cornwall, but charles the prince of wales? why is he a prince, not a duke? | He is also a Duke. But Prince is a higher title than a Duke so it takes precedence and is the primary title he goes by when using a shortened title.
His full title is : His Royal Highness Prince Charles Philip Arthur George, Prince of Wales, KG, KT, GCB, OM, AK, QSO, CC, PC, ADC, Earl of Chester, Duke of Cornwall, Du... | [
"Camilla, Duchess of Cornwall, (born Camilla Rosemary Shand, later Parker Bowles; 17 July 1947), is a member of the British royal family. She is the second wife of Charles, Prince of Wales, heir apparent to the British throne. Instead of using the title Princess of Wales, she uses the title Duchess of Cornwall, her... |
Why was the Communist Manifesto published specifically in the "English, French, German, Italian, Flemish and Danish languages"? | _URL_1_ has copies of the [Prefaces](_URL_2_) to various editions of the Communist Manifesto, written by Marx and Engels, that give some history around the languages in which it was published.
The original version was commissioned by the Communist League (formed in 1847) and published in German in London in February 1... | [
"Although the \"Manifesto\"s prelude announced that it was \"to be published in the English, French, German, Italian, Flemish and Danish languages\", the initial printings were only in German. Polish and Danish translations soon followed the German original in London, and by the end of 1848, a Swedish translation w... |
if cellphones are replacing landlines, why aren't there versions of white pages for cellphones? how are landlines any different? | Problem Is there are multiple cell phone companies, so if each had their own book it would be incomplete and inconvenient to have to look through 5 books to find a person. Land lines used to be one company in an area generally. It was a weird deal because they were a company, but a utility and basically a monopoly. Eve... | [
"As the recipient of a mobile call pays airtime, standard mobile phone numbers are not uniquely different from land-line numbers and thus follow the same format and area codes as for land-lines. Numbers may be ported between landline and mobile. The rarely used non-geographic area code 600 is one exception to this ... |
reddit - why do americans use the dutch flag to make clear their store is open (or that they have used cars etc.)? | You might be interested in [this recent thread from /r/vexillology](_URL_0_). Nobody seems to know a definitive reason why. The most common belief is that it doesn't have anything to do with the Netherlands, and is just a way to put red-white-blue and a message on a flag. | [
"In a sense of patriotism, each car featured American flags. Ken Schrader removed every sponsor and decal from his car and completely painted the car as an American flag, a process that sponsor M&M's would recreate ten years later for Kyle Busch at the 2011 Wonderful Pistachios 400.\n",
"Online Stores opened its ... |
Short sightedness and a mirror | Yes, as far as the focus of your eye is concerned, it's as if you were looking at a face 4m away. | [
"An optician, or \"dispensing optician\", is a technical practitioner who designs, fits and dispenses corrective lenses for the correction of a person's vision. Opticians determine the specifications of various ophthalmic appliances that will give the necessary correction to a person's eyesight. Some registered or ... |
how is it that some mirrors make me look slightly fat and some otbers make me look slightly thin? | Lighting can play a big role in how good you feel you look, but mostly I think you're referring to mirrors that are slightly curved. A very slight curve inward can may you look leaner and even a bit taller, proportionally. Slightly curved outward and the mirror can make you look a little fatter. | [
"Round convex mirrors called \"Oeil de Sorcière\" (French for \"sorcerer's eye\") were a popular luxury item from the 15th century onwards, shown in many depictions of interiors from that time. With 15th century technology, it was easier to make a regular curved mirror (from blown glass) than a perfectly flat one. ... |
What happens if I don't finish my strip of antibiotics? Also what does timing matter? | These things matter A LOT. It's extremly serious. Please, please, *please* do not ignore your doctor's advice on this matter. Doing so will be a problem not only for you, but for all of us. **Please**.
The huge problem with antibiotics is that bacteria can develop [resistance](_URL_0_) to them. A lot of antibiotic-res... | [
"A course of one week of antibiotics is usually sufficient to treat the condition. However, if the condition recurs, antibiotics can be given in a cyclical fashion in order to prevent tolerance. For example, antibiotics may be given for a week, followed by three weeks off antibiotics, followed by another week of tr... |
Why did the US in the Pacific Theater during World War 2 choose certain islands to invade while ignoring others? | When explaining their strategy both during the war and after, a number of US Army planners quoted the famous American baseball player Willie Keeler. When asked how he hit home runs, Keeler said that he "hit them where they ain't." (in short, hit the ball where there was no opposing fielder) The leapfrogging strategy as... | [
"In order to capture the islands from Japan, the United States military employed a \"leapfrogging\" strategy which involved conducting amphibious assaults on selected Japanese island fortresses, subjecting some to air attack only and entirely skipping over others. This strategy caused the Japanese Empire to lose co... |
how do we genetically modify cells and viruses? | First a piece of DNA is created, or often taken from somewhere else, that does some desired thing. This could be making a specific protien, or hormone like insulin that we want or need. For anti-cancer viruses, depending on the method being attempted, it could be DNA to mark cancer cells for the body to identify and at... | [
"Viruses infect cells by transducing their genetic material into a host’s cell, using the host’s cellular machinery to generate viral proteins needed for replication and proliferation. By modifying viruses and loading them with the therapeutic DNA or RNA of interest, it is possible to use these as a vector to provi... |
how do the silica bead packets remove moisture from the stuff around them? | Silica, also known as silicon dioxide is what we refer to as a “desiccant” which means it has the ability to “pull” or adsorb water. It does this because the thin layers of water molecules are attracted to the high surface area of the beads. It has thousands of holes of pores that can adsorb 40 percent of its weight. ... | [
"Silica gel beads, familiar for removing moisture from packaging containers, are a third alternative. These are \"calibrated\" with a coating of mineral salts to absorb or release humidity in various RH ranges (including 65%, 68%, 70%, and 72%), providing a buffering effect on relative humidity. They require only d... |
why does pastry go all soggy in the microwave, but all crispy in the oven? | Microwave keeps moisture, just vibrates it to create heat. Oven heats the moisture so much it evaporates. | [
"BULLET::::- Flaky pastry: Flaky pastry is a simple pastry that expands when cooked due to the number of layers. It bakes into a crisp, buttery pastry. The \"puff\" is obtained by the shard-like layers of fat, most often butter or shortening, creating layers which expand in the heat of the oven when baked.\n",
"P... |
what's going on with the comey testimony? | Trump tried to get Comey (who was head of the FBI at the time) to drop the investigation into his staff's involvement in Russia influencing our election.
> The President then returned to the topic of Mike Flynn, saying, ... "I hope you can see your way clear to letting this go, to letting Flynn go. He is a good guy.... | [
"The storyline is about a testimony found in an old wooden desk and advocate couple van Dalen claiming the rights of it. After a big manhunt (everybody wants the testimony), it comes back to the finder and rightful owner.\n",
"Before her testimony, the TMLC filed a motion to have her excluded as an expert witness... |
Does passing light though a prism in space or water or ice change the separation of colors? | Yes. First off, the angle of refraction changes based on the ratio of the [refractive indices](_URL_3_) of the two materials, obeying [Snell's law](_URL_4_).
Secondly, the amount of [dispersion](_URL_1_) - how much the angle of refraction depends on the wavelength - is dependent on the material. For instance, in photo... | [
"As opposite to air, water attenuates light exponentially. This results in hazy images with very low contrast. The main reasons for light attenuation are light absorption (where energy is removed from the light) and light scattering, by which the direction of light is changed. Light scattering can further be divide... |
why i automatically get sleepy whenever i travel on a plane, bus or train, even if i've had a good nights sleep. | the white noise, the gentle rocking of the train/bus, the relatively comfortable seats, the monotony and lack of stimulation of it all makes you want to fall asleep. airplanes are different as the seats are cramped and you can't fall asleep as easily. | [
"Due to the work nature of airline pilots, who often cross several timezones and regions of sunlight and darkness in one day, and spend many hours awake both day and night, they are often unable to maintain sleep patterns that correspond to the natural human circadian rhythm; this situation can easily lead to fatig... |
why and how does china get away with such blatant copying of patented and protected items when it is a member of world trade organisation? | > I haven't seen any such measures being taken against China.
The WTO does have meetings about this regularly, but the WTO is mostly toothless, and trade agreements are usually bilateral.
The US files complaints, the Chinese do actually have decent IP laws on the books but they're weakly enforced (or not enforced... | [
"In April 2007, the United States government filed action against China with the World Trade Organization for violating intellectual property rights. The suit was brought because it was believed the Chinese government was not acting against copyright infringement as a criminal offense.\n",
"In 1998 \"Interim Regu... |
How accurate is this "information" that I keep seeing about viking women on Facebook and what was the reality? | I'm taking a Icelandic sagas class which focuses on Icelandic culture and law. (Nordic studies minor)
At least in Iceland a woman needed 3 witnesses to divorce her husband, while a man could divorce his wife with a single witness any time anywhere. As far as honor, that would lie more in how things are resolved in the... | [
"It is evident that the main characters of the saga are the exclusively male jarls and kings and their male supporters and antagonists. Nonetheless, it is believed that women enjoyed a relatively high status during the Viking Age, possibly due to the high degree of mobility in society and they regularly appear in s... |
why do people continue to live in california if scientists are fairly certain the big one will hit (with major consequences)? | Because we can prepare for earthquakes. Take a look at Japan, a country that is used to having a lot of earthquakes. Their buildings are designed to be able to withstand the force of a quake, and its actually [quite effective](_URL_1_). Same with California. They prepare for and take appropriate measures. One example o... | [
"There are several large threats to this region. Many of California’s large population centers are located within it which causes stress on the surrounding environment because people have a desire to move to California so new homes and industry have to be established in order to accommodate all of the people moving... |
how come some faces are blurred out and some can be shown in a reality show? | Most people who have not been blurred out are specifically asked for their permission with a little money to grease their fingers. Reality shows cannot display someone's image without their consent.
The blurry ones are the guys who didn't consent. | [
"Initially, some staff opted out of participating, thus requiring the production team to blur their faces if they appeared incidentally in a scene that was used in the final edit, but in the end, more than 2000 people gave their consent to appear in the show. The camera crew also avoided filming certain patients un... |
why can't airlines save time when flying from america to europe by flying over the north pole? | They fly the most efficient route possible, while still maintaining compliance with ETOPS regulations. Often the route is as close to possible to the [great circle](_URL_1_)
ETOPS specifies the distance a plane can be from the nearest airport, incase of an in-flight mechanical or medical emergency.
Officially, ETOPS... | [
"North–south flights that do not cross time zones do not cause jet lag. However, crossing of the Arctic Ocean or even the North Pole (often the shortest route between northeast Europe and Alaska or the Canadian West Coast and East Asia) does cause a significant time change. Jet travel from Alaska to northeast Europ... |
why is there no consensus whatsoever among health experts whether coffee is good for you or not? | You can't just say something is good or bad for your health. If you drink 12 liters of water, you will most likely die. Does that mean water is bad for you? Of course not.
Coffee contains huge amounts of different compounds, many of those have an effect on our body. One compound may have multiple effects - consider, f... | [
"A 2017 review of clinical trials found that drinking coffee is generally safe within usual levels of intake and is more likely to improve health outcomes than to cause harm at doses of 3 or 4 cups of coffee daily. Exceptions include possible increased risk in women having bone fractures, and a possible increased r... |
Do other the other forces curve spacetime? | Not in the same way that gravity does, because gravity **is** the curvature of spacetime. However, other forces contribute energy density to a system, which in turn increase the strength of its gravitational field (or the bending of spacetime, if you will). For example, a charged capacitor or a nuclear isomer will grav... | [
"If Einstein showed that space-time was curved, Nottale shows that it is not only curved, but also fractal. Nottale has proven a key theorem which shows that a space which is continuous and non-differentiable is necessarily fractal. It means that such a space depends on scale.\n",
"While we can't choose a coordin... |
Do animals get tight muscles and knots like humans do? Do they hold stress in their muscles like humans? | Yes animals can get tight and knotted the same way people can! This occurs most commonly in competition animals, very active animals, or animals that have physical conditions that lead to stiffness. As a pre-vet student I saw this most commonly in the backs of older riding horses. This is why there are veterinary chiro... | [
"The muscles and nerves are much simpler than those of most other animals, although more specialised than in other cnidarians, such as corals. Cells in the outer layer (epidermis) and the inner layer (gastrodermis) have microfilaments that group into contractile fibers. These fibers are not true muscles because the... |
when i have a full bladder during the night, i sometimes dream that i pee. what keeps me body from actually wetting the sheets? | Both nocturnal penile tumescence (morning wood) and REM atonia (a purposeful block from activating normal muscles while dreaming so that you don't sleepwalk or kick your dog or eat your pillow) prevent you from peeing the bed. | [
"\"Urinating in bed is frequently predisposed by deep sleep: when urine begins to flow, its inner nature and hidden will (resembling the will to breathe) drives urine out before the child awakes. When children become stronger and more robust, their sleep is lighter and they stop urinating.\"\n",
"The possibility ... |
Could a Jewish person avoid the holocaust if he converted to another religion? | No, absolutely not.
Hitler retained less control over the SA and Gestapo [than one might think](_URL_0_), so that one case you mentioned is likely a. untrue b. mischaracterized c. an anomaly.
Nazi understandings of Judaism were really hard to characterize, especially when it gone down to the issue of who was "Jewish ... | [
"One could not become a non-Jew in the eyes of the Nazi government by seceding from one's Jewish congregation, becoming non-practicing, marrying outside the religion, or converting to Christianity. In 1935 the Nuremberg Laws forbade new marriages of people classified as Jews with people of other classifications. Ea... |
When exactly did New York replace London as the capital of international finance? | Hmmm. This is pretty far outside my area of specialty and I can only comment briefly from what I've seen in newspapers and *The Economist,* but I was under the impression that NYC may not actually have usurped that title. London has a few advantages -- some of them recent, some of them permanent -- that makes it diffic... | [
"At this time the City of London was becoming the world's leading financial centre, superseding Amsterdam in primacy. The Bank of England was founded in 1694, and the British East India Company was expanding its influence. In 1700 London handled 80% of England's imports, 69% of its exports and 86% of its re-exports... |
[meta] hey everyone! | In my opinion, subreddit styling distracts from the content. I like all of my subs to have a uniform look and feel. The default styling does a great job of emphasizing the content, which is what reddit is about. | [
"The original online sources refer to the list with the following quote: \"Meet the most influential people in the world. They are artists and activists, reformers and researchers, heads of state, and captains of industry. Their ideas spark dialogue and dissent and sometimes even revolution. Welcome to this year's ... |
why do guns have recoil? | Conservation of momentum / force / acceleration. For the bullet to be pushed forward, the gun must be pushed backward. The bullet is a small mass with a high acceleration, while the gun is a large mass with a smaller acceleration. | [
"Perception of recoil is related to the deceleration the body provides against a recoiling gun, deceleration being a force that slows the velocity of the recoiling mass. Force applied over a distance is energy. The force that the body feels, therefore, is dissipating the kinetic energy of the recoiling gun mass. A ... |
How do they determine the mass of a blackhole? | Depends on the context.
If you see something orbiting the black hole, you can determine its mass, as the orbit is determined by the gravitational influence of the black hole. [Here](_URL_0_) is an actual video of stars moving around the black hole at the center of our galaxy, and [here](_URL_1_) is a page with a littl... | [
"One group made observations using the Gemini Near Infrared Integral Field Spectrometer to better determine the mass of the black hole at the center of NGC 1277. The group used similar models to that of van den Bosch, but with higher spatial resolution. After using stellar dynamics and luminosity models to estimate... |
Could dropping a bullet set it off? | /u/gabe0421 is right. Yes a bullet could potentially be set off if it falls just in the right angle from the right height etc.
This however is extremely unlikely to happen. The primer (the part that ignites the gunpowder in the ammunition) needs to be hit by enough force and is rather small. Most ammunition of rifles... | [
"BULLET::::- 2. Drop Flat On Ground Or Floor: To keep from being tossed about and to lessen the chances of being struck by falling and flying objects, flatten out at the base of a wall, or at the bottom of a bank.\n",
"BULLET::::- Bomb - A bomb is tossed into the opponent's field with a timer on the front of it. ... |
why can't the keystone pipeline go around standing rock? | Well, first off, it's DAPL that goes near Standing Rock, not Keystone XL. DAPL goes just north of the reservation right now, but if there is a leak, the water in the reservation would be affected, which the protesters want to prevent. At this point, they are going on with construction, so it will be tough to convince t... | [
"The Keystone Pipeline is another oil pipeline system that began its construction in 2010, also causing political, environmental, and Indigenous Issues in the South Dakota reservation. In 2017, this pipeline was reported to have leaked 210,000 gallons of oil on the land, potentially affecting wildlife and water sou... |
[Physics] Could a human swim in a column of water only supported by atmospheric pressure? | Sure. Swimming in the column at a particular height would physically feel similar to swimming in a body of water at the corresponding atmosphere height.
For example, the correspondence to Lake Titicaca at about 3,800m (atmospheric pressure about 63 kPa according to standard atmosphere) would be about 3.8m up the col... | [
"Swimming relies on the nearly neutral buoyancy of the human body. On average, the body has a relative density of 0.98 compared to water, which causes the body to float. However, buoyancy varies on the basis of body composition, lung inflation, and the salinity of the water. Higher levels of body fat and saltier wa... |
What happens when wind travels faster than the speed of sound? | In isolation, not much. Wind traveling faster than the speed of sound in isolation is still just wind. But, if that supersonic wind hits a stationary object, it will create a sonic boom and knock that object forcefully. A jet flying faster than the speed of sound through stationary air is identical to wind blowing fast... | [
"BULLET::::- Motion of the medium itself. If the medium is moving, this movement may increase or decrease the absolute speed of the sound wave depending on the direction of the movement. For example, sound moving through wind will have its speed of propagation increased by the speed of the wind if the sound and win... |
body in space without a suit | > How long time would you survive in space without of a space suit?
A few minutes, barring unfortunate circumstances (well, *more* unfortunate anyway) like being near a star or something.
> What would kill you and why?
Oxygen deprivation. In the absence of an atmosphere, your lungs would actually speed this proces... | [
"In space, astronauts use a space suit, essentially a self-contained individual spacecraft, to do spacewalks, or extra-vehicular activities (EVAs). Spacesuits are generally inflated with 100% oxygen at a total pressure that is less than a third of normal atmospheric pressure. Eliminating inert atmospheric component... |
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