Split (2)

train · 226k rows

question stringlengths 3 301	answer stringlengths 9 26.1k	context list
When exactly did the migration of free settlers to the Australian colonies begin to match or exceed the transportation of convicts?	The [first proper census of people in the New South Wales colony - i.e., Australia - was conducted in 1828](_URL_0_), and it counted 36,287 people. Of these, 5210 had came to Australia as free settlers, 8388 were born in the colony and the rest had been transported to Australia as convicts (though of 22,689 others, onl...	[ "The British Government then looked to the newly discovered east coast of Australia to use as a penal colony. Convicts were transported to Australia in 1787, arriving in Botany Bay, then Sydney Cove, in January 1788. From the very start of European settlement convicts were used as indentured labourers in five out o...
why is it so hard for doctors to make breast implants look natural?	It isn't. New boob jobs are fantastic. The problem arises when women go for a size that is WAY too big for their body type, or go too big too quickly. My wife has a boob job and it is virtually impossible to tell, unless you find the (miniscule) scar.	[ "Facial implants are used to enhance certain features of the face. The surgery may be elective, or needed as the result of prior surgery on the face. Each involves placing synthetic materials deep under the subcutaneous tissue and onto the underlying bone. A maxillofacial or plastic surgeon uses them to aesthetical...
What makes transition metals the densest elements?	Additionally to the high density, transition metals also have high melting and boiling points. From that you can already guess, it has to to with stronger bonding between the different atoms. > The IUPAC definition defines a transition metal as "an element whose atom has a partially filled d sub-shell, or which can ...	[ "High-density materials tend to sink through lighter materials. This tendency is affected by the relative structural strengths, but such strength is reduced at temperatures where both materials are plastic or molten. Iron, the most common element that is likely to form a very dense molten metal phase, tends to cong...
What was the 101st Airborne's role in the Battle of Normandy?	The major purpose of airborne forces on D-Day was to protect the flanks of the invasion force by securing choke points, disrupting enemy forces and defending against counter attacks. [This image]( _URL_0_) shows the insertion of airborne forces, look for the blue aircraft silhouettes at either end of the invasion beac...	[ "The 101st Airborne Division fought two battles in Normandy after D-Day. The first, at Saint Côme-du-Mont, was to complete its objective of blocking possible German counterattacks from south of the Douve River and is considered part of its original airborne mission.\n", "During the D-Day Invasion, the squadron dr...
Why is silver anti-microbial?	Medical Student who majored in Microbiology and Molecular Biology here: Silver has been known for hundreds of years as an antimicrobial. It is thought that since silver has a propensity to interact with the thiol groups, ( -SH groups), it denatures proteins by disrupting these bonds. Proteins without proper disulphide ...	[ "Silver and most silver compounds have an oligodynamic effect and are toxic for bacteria, algae, and fungi \"in vitro\". The antibacterial action of silver is dependent on the silver ion. The effectiveness of silver compounds as an antiseptic is based on the ability of the biologically active silver ion () to irrev...
racism on 4chan	op is a faggot	[ "4chan users have been instrumental in pranks such as hijacking Internet destinations to cause images of Rick Astley to appear in place of their content, coordinating attacks against other websites and Internet users, exposing animal abuse, and posting threats of violence in order to elicit individual and public re...
how do mres work?	They use a magnesium heater. It's a small, teabag-like, pouch of magnesium in a heat-resistant plastic bag. You pour a small amount of water into the bag, and it reacts with the magnesium to create heat. Then you put the food, also in a heat resistant pouch, in the bag with the magnesium and water, and this reheats ...	[ "A mail retrieval agent (MRA) is a computer application that retrieves or fetches e-mail from a remote mail server and works with a mail delivery agent to deliver mail to a local or remote email mailbox. MRAs may be external applications by themselves or be built into a bigger application like an MUA. Significant e...
What exactly is the difference between carbon fiber and fiberglass?	Try the other way of spelling fibre, you get better [results](_URL_0_). You can also do things in Google like subtract words that you don't want to see in your search. For example, searching for "carbon fibre vs fibreglass -car" returns much better results and a search without -car.	[ "Carbon fibers or carbon fibres (alternatively CF, graphite fiber or graphite fibre) are fibers about 5–10 micrometres in diameter and composed mostly of carbon atoms. Carbon fibers have several advantages including high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolera...
how is there always a relevant xkcd? how!?	I imagine it functions along the same lines as Quantum Fetish Mechanics. By the time you think of it, it already exisists on the internet.	[ "When \"Xr\" = \"Xmin\", where \"Xmin\" is the unique minimum value observed, it is found that \"Fc\" = 1/\"N\", because \"M\" = 1. On the other hand, when \"Xr\"=\"Xmax\", where \"Xmax\" is the unique maximum value observed, it is found that \"Fc\" = 1, because \"M\" = \"N\". Hence, when \"Fc\" = 1 this signifies ...
; why are tattoos such taboo in some religions?	Some religions believe your body is the physical property of God. You are just borrowing it for your time on Earth and at the end when you die he gets it back. You're not allowed to damage it because it's not yours and a tattoo is damaging the skin.	[ "The majority of Sunni Muslims believe tattooing is a sin, because it involves changing the natural creation of God, inflicting unnecessary pain in the process. Some Shafi'i scholars such as Amjad Rasheed argue that tattooing causes impurity and that tattoos were prohibited by the Prophet Muhammad. They also claim ...
Why don't we wear fancy clothes as much anymore?	I can't speak to the cyclical nature of clothing, but I think your first question has a rather simple answer - baby boomers. The Baby Boom generation that was born in the 40s and 50s, came of age as "hippies" in the 60s and 70s. Suits and hats for everyday wear was what their parents wore. The movements embraced by the...	[ "There are also goods that are perceived as luxurious by the public simply because they play a role of status symbols as such goods tend to signify the purchasing power of those who acquire them. These items, while not necessarily being better (in quality, performance, or appearance) than their less expensive subst...
Source of metals in Antiquity	The common sources of iron ore that are easily accessible without mining are bog iron and iron sand. Bog iron, as the name suggests, is found in bogs and similar moist environments (e.g., along streams); the deposits of ore are formed by bacteria (which will make new ore, and the bog can be reharvested after a decade o...	[ "The metals of antiquity are the seven metals which humans had identified and found use for in prehistoric times: gold, silver, copper, tin, lead, iron, and mercury. These seven are the metals from which the modern world was forged; until the discovery of arsenic in the 13th century, these were the only known eleme...
When and what marked the transition between "Old West" towns just becoming known as regular towns?	The influential contemporary historian Frederick Turner famously declared that the frontier (akin to 'Old West') in 1890 whereby the Native American population, harshness of the landscape and much of the mystery and intrigue of lands to be explored had been mitigated and suppressed [1]. This trend evidenced it can be...	[ "In the late 19th century, West City was a small settlement adjoining Benton on the west. In the early 20th century many immigrants from Poland, Lithuania, and England settled in the West City area to work in the numerous coal mines.\n", "It was founded in 18th century colonial times and was initially called \"Sh...
what are graphics apis such as directx or vulkan and what do they do?	(Technical note, DirectX actually covers a bunch of things like sound and input, we'll assume we are talking about the Direct3D portion of DirectX which is what Vulkan does) They both provide an abstraction layer, a language or set of commands, between the graphics card and the software that wants to use it. It means ...	[ "The Vulkan API provides the intermediate SPIR-V representation to describe \"both\" Graphical Shaders, and Compute Kernels, in a language independent and machine independent manner. The intention is to facilitate language evolution and provide a more natural ability to leverage GPU compute capabilities, in line wi...
why don't snakes choke when they devour large prey whole / is it ever possible for a snake to choke ?	Yes, snakes can choke. Sometimes they start to swallow a prey, and when startled or find that it is too big, they reverse the swallowing process. It's usually not healthy for the snake to do repeatedly, and can hurt the snake. Also, snakes have a special extendable tube trachea they push forward to the front of their ...	[ "In \"Dungeons & Dragons\", chokers are solitary, elusive, vicious creatures shrouded in mystery. A choker's only desire in life seems to be to kill those it encounters and run off. Using its padded tentacles it can climb and crawl on almost any surface, and it catches prey by lurking above doorways, archways, stai...
What determines which areas of the brain are damaged during hypoxia?	Generally the areas damanaged depened on two factors * metabolic demand * blood supply The first factor should be obvious. Neurons that have high resting metabolic demand are going to run out of energy first. Note that the brain depends on aerobic energy production and can't really get by like muscles do with anaer...	[ "A closely related disease to brain ischemia is brain hypoxia. Brain hypoxia is the condition in which there is a decrease in the oxygen supply to the brain even in the presence of adequate blood flow. If hypoxia lasts for long periods of time, coma, seizures, and even brain death may occur. Symptoms of brain hypox...
why are basements (even finished ones!) still a smooth 10-15 degrees cooler than the rest of a house?	Because basement floors are made of a small cement pad over dirt which is usually a good 8+ ft below grade. This is far enough down to not really be subjected to much seasonal temperature changes.	[ "Structurally, for houses, the basement walls typically form the foundation. In warmer climates, some houses do not have basements because they are not necessary (although many still prefer them). In colder climates, the foundation must be below the frost line. Unless constructed in very cold climates, the frost li...
2nd Time: Why did the Nazis appropriate so much ancient Mediterranean culture if they were trying to recreate a Germanic state?	Well first, Nazi beliefs were not a coherent and logical whole philosophy and aesthetic by any standard, and different Nazis believed very different things. Some of the artists the Nazis denounced as 'degenerate art' had themselves been long-time party members. Second you have the stylistic time period in which they we...	[ "The Nazis regarded central/southern Italians, Spanish, Portuguese, southern French, and Greeks as sharing a similar origin with Germans from ancient Indo-Aryan migration, but being almost purely of a distinct so-called Mediterranean race. Despite classifying these populations as Aryans, and regarding them as super...
why can't you get prosecuted for posting videos/picture of yourself doing drugs while you can for posting a murder you've committed?	Typically the picture is a starting point for an investigation. If you post a picture of you doing drugs, they interview you and you say "fifth amendment" or "it wasn't drugs. It was something that looks like but isn't drugs," that's where the investigation ends. If you post a picture/video of you killing someone, ...	[ "Since 2011 prosecutors can elect to drop the charges if the amount of drugs seized is of a limited quantity (although no set limit is explicitly stated) and the drugs seized are believed to be for personal consumption only.\n", "Defendants are often prosecuted and convicted under provisions of statutes such as t...
the effectiveness of "traditional" advertising?	Companies have often wondered the same, and several have tried cutting the ad budget over the years. Usually they see sales drop by more than the budget is worth. So yeah, it makes a difference. Ask yourself this - you need to get some random product you don't buy much and have no sense of where to get good ones or w...	[ "Advertising tries to expand consumption in two ways; it both reminds and teaches. It reminds in-the-market consumers in order to influence their immediate brand choice and teaches to increase brand awareness and salience, which makes it easier for future advertising to influence brand choice. Adstock is the mathem...
why do things sound significantly different when you listen to them with one ear vs both ears? for example when only using one out of a pair of headphones, even when listening to things recorded in mono.	For the same reason things look different when you look at them with one eye versus with two eyes (or at least, they should!). Just like we humans have binocular (bi-n-ocular, two eyes) vision, we have binaural (bi-n-aural, two ears) hearing. When you see something with just one eye, you lose a whole lot of information...	[ "For a time it was thought that the inner ear was solely responsible whenever a sum or difference tone was heard. However, experiments show evidence that even when using headphones providing a single pure tone to each ear separately, listeners may still hear a difference tone. Since the peculiar, non-linear physics...
What was the highest rank awarded to a U.S. black soldier/officer in WW2?	EDIT- I misconstrued the title and saw it as rank/award...which is why I chimed in with what I wrote below. While not directly answering the question, I'm sure followup questions would have asked this. Well, First Lieutenant Vernon Baker's actions in early '45 would earn him a Bronze Star, which was upgraded to...	[ "BULLET::::- Martin Delany (May 6, 1812 – January 24, 1885) was commissioned as a major, the first black line field officer in the war and achieving the highest rank an African American during the war.\n", "Paul Levern Bates (March 4, 1908 – February 21, 1995) was a United States Army officer. He served a disting...
genetically modified organisms	Every organism has within it a set of instructions for how that organism is made and what it does. This is DNA. DNA is like an alphabet with only four letters. By spelling out different 'words' using these 'letters', we get the 'instructions' that describe the organism. A genetically modified organism is made when a...	[ "Genetically engineered organisms are genetically modified in a laboratory, and therefore distinct from those that were bred through artificial selection. In the fields of agriculture, agroforestry and animal husbandry, \"genetic pollution\" is being used to describe gene flows between GE species and wild relatives...
Prior to gunpowder what was the most effective military deployment?	I think you must mean 'development.' "What was the most effective military development?"	[ "The advent of gunpowder warfare meant that an army could no longer rely solely on foraging in the surrounding countryside, and required a regular supply of munitions. In the 18th century, organized commissary and quartermaster departments were developed to centralize delivery of supplies. The delivery took the for...
How did the stereotype of African Americans being lazy come about?	Ooh I question I might be able to answer since some of my research is dealing with this. Unfortunately I'm on my phone so this will have to be a bit brief before I can come back and edit it. A lot of it has do with how slaves were portrayed in plantation novels(many of them were responses to Uncle Toms Cabin). Those ...	[ "\"The Right to be Lazy\" is an essay by Cuban-born French revolutionary Marxist Paul Lafargue, written from his London exile in 1880. The essay polemicizes heavily against then-contemporary liberal, conservative, Christian and even socialist ideas of work. Lafargue criticizes these ideas from a Marxist perspective...
Can marine animals taste salt? Would they know if the concentration changes?	As far as "taste" I'm unsure, as for concentration their bodies certainly can tell! Salt (NaCl) is incredibly important in animal bodies, it helps power many of the important cellular processes of the body. But too much salt can also be detrimental to the body. The gills of a fish are important not only for respirati...	[ "They have certain adaptations to live within their salty environments. For example, their cellular machinery is adapted to high salt concentrations by having charged amino acids on their surfaces, allowing the cell to keep its water molecules around these components. The osmotic pressure and these amino acids help...
What did the Family of Queen Victoria do for entertainment?	Let's use family in this context to mean immediate family, as in her husband and children. As a child, heir to the throne Prince Edward really did not have too much of a childhood. He was caged inside an intensive education system which did not leave much time for traditional childhood play. However as an adult, he e...	[ "Victoria married her cousin Albert in 1840. Their children married into royal and noble families across the continent, earning Victoria the sobriquet \"the grandmother of Europe\" and spreading haemophilia in European royalty. After Albert's death in 1861, Victoria plunged into deep mourning and avoided public app...
How is the power of nuclear weapons increased?	So most nuclear warheads in the current stockpile are of the Teller-Ulam design. You have a small(ish) fission primary, which initiates the whole thing. This creates the conditions necessary for fusion in the secondary. The neutrons produced in the secondary, in turn, cause fission in the natural uranium casing that su...	[ "According to Mark Z. Jacobson, the growth of nuclear power has \"historically increased the ability of nations to obtain or enrich uranium for nuclear weapons, and a large-scale worldwide increase in nuclear energy facilities would exacerbate this problem, putting the world at greater risk of a nuclear war or terr...
Why am i supposed to skip a dosage of my daily medication if I'm too late to take it by a few hours?	In practice it depends on the drug. Different drugs have different pharmacokinetics (PK), that is the disposition of the drug within the body (e.g., absorption into blood, distribution to tissues, metabolism, filtration into urine) that affect it's plasma concentration (Cp) vs time (t) profile: a tool commonly used in ...	[ "Take one tablet by mouth at the same time every day. The failure rate may increase when pills are missed or taken incorrectly. Single missed pills should be taken as soon as remembered. It is important to know that when experiencing stomach upset in the form of diarrhea or vomiting (within 3–4 hours of taking), ba...
why do some people still think that homosexuals shouldn't be allowed to serve in the military?	Not really LY5 but here goes: Some straight men project their own sexual appetite onto gays and then make predictions about the behavior of gays in an overwhelmingly male environment. Some believe that the military is among the 'most manly' and 'most honorable/virtuous' institutions. Some also believe that homosexua...	[ "Homosexuals are allowed to serve openly in the United States military. Military policy and legislation had previously entirely prohibited gay individuals from serving, and subsequently from serving openly, but these prohibitions were ended in September 2011 after the U.S. Congress voted to repeal the policy.\n", ...
how does the reusable gel heating pads work?	There is a chemical mixture inside, that when excited (by the metallic disk being clicked) produces a self-sustaining exothermic reaction. What this means in layman speak is that the reaction, once started, will continue on its own until it runs out of material, and that the reaction releases heat. When you heat the p...	[ "The most common reusable heat pads contain a supersaturated solution of sodium acetate in water. Crystallization is triggered by flexing a small flat disc of notched ferrous metal embedded in the liquid. Pressing the disc releases very tiny adhered crystals of sodium acetate into the solution which then act as nuc...
If you cover one eye, how does your brain know to somewhat prioritise what the uncovered eye is seeing?	the simple answer is that what you see is a nonlinear sum of the inputs from the two eyes - in terms of apparent contrasts (brightnesses and darknesses), what you see is approximately equal to the square root of the sum of the squares of the physical contrast (change in retinal illuminance over space) in both eyes. [he...	[ "The retina at the back of the eye is what perceives stimuli, allowing them to travel through the occipital tract to the lateral geniculate nucleus (LGN) within the thalamus. The data is then transmitted to the occipital lobe where the orientation and other recognizable factors are processed.\n", "When searching ...
What are the origins of modern day Balkland peoples? E.g Albanian, Serbs, Croats etc...	For Albanians the most accepted theory is either illyrian origin or thracian-dacian origin. All 3 were native balkan people. For slavs like the croats serbs etc most likely extended out from lands near belarus and north ukraine	[ "The Sarmatians were eventually decisively assimilated (e.g. Slavicisation) and absorbed by the Proto-Slavic population of Eastern Europe around the Early Medieval Age. Scholars have connected the ethnonym with those of the Slavic peoples of Serbs and Croats in Europe. There is a theory that \"Horoati\" and their k...
if we know so much about the human body, why is there so much conflicting information on topics like weight loss and muscle gain?	Basically, because the weight loss and fitness industries are huge, and people want to make money. Really the basics always boil down to "eat less calories, exercise more", but plenty of folks like to dress that up in order to turn a profit.	[ "Mounting evidence indicates that the amount and type of fat in the diet can have important effects on bone health. Most of this evidence is derived from animal studies. The data from one study indicated that bone mineral density is negatively associated with saturated fat intake, and that men may be particularly v...
Why did eukaryotes develop linear chromosomes if it gives us problems with telomeres? Wouldn't it have been evolutionarily advantageous for all organisms to keep circular chromosomes?	There is greater genetic availability with linear duplex chromosomes due to cross over. Also, there is less problem with frameshift reading killing the organism with linear vs. circular chromosomes...	[ "The content of a chromosome would be changed mainly by mutation after duplication of the chromosome and translocation with other chromosomes. However, in mammals, since the chromosomal sex-determination mechanism would have been established in their earlier stages of evolution, polyploidy would have not occurred d...
I have a science degree but I'm not yet prepared to study some areas of physics. What math should I review, and what math should I study to understand the meaning behind quantum equations?	What areas of physics are you interested in? For undergrad physics (until special relativity and quantum mechanics), linear algebra and differential equations are everywhere. You should also know at least the cool results from multivariable analysis (gauss, stokes, etc), and the theory to solve laplace's and poisson e...	[ "A standard undergraduate physics curriculum consists of classical mechanics, electricity and magnetism, non-relativistic quantum mechanics, optics, statistical mechanics and thermodynamics, and laboratory experience. Physics students also need training in mathematics (calculus, differential equations, linear algeb...
Is it a coincidence that most of the major powers of the world are in the northern hemisphere?	Well, 67% of the land and 90% of the human population is in the northern hemisphere. A quick look at geography shows that a significant proportion of this southern land is desert. The hemispheres didn't really have a level playing field to start with.	[ "With an estimated population of 380 million and an area of 21,346,000 km² (824,714 mi²), the northernmost of the two continents of the Western Hemisphere is bounded by the Pacific Ocean on the west; the Atlantic Ocean on the east; the Caribbean Sea, Atlantic and Pacific oceans, and South America on the south; and ...
how did french, german and italian speaking (and some other) people decide to become switzerland together, instead of the germans becoming german, the french becoming french, etc. ?	Switzerland formed before the concept of a "nation state" was a popular thing. So people who spoke French didn't necessrily feel like they had to be part of the same country as other French speaking people. Germany and Italy weren't even unified countries by that point. By the time nationalist movements gained momentu...	[ "Switzerland is a majority German-speaking country that absorbed many German military traditions alongside those of France and Italy. The Swiss Armed Forces abandoned the goose step in 1946, after the German defeat in World War II.\n", "As there is no dominant national language, the four main languages of French,...
The ability to curl one's tongue is a common example used to explain phenotypes and genotypes. What actually causes this phenotype when the appropriate genotype is present?	Hey GoonCommaThe, As far as I recall, it's currently a myth that the ability to curl one's tongue is regulated genetically. Here's an article that can shed more light; _URL_0_ It's possible that some individuals just have better ability to control the intrinsic muscle of the tongue, but everyone still has these mus...	[ "In contrast to phenotypic plasticity, the concept of genetic canalization addresses the extent to which an organism's phenotype allows conclusions about its genotype. A phenotype is said to be canalized if mutations (changes in the genome) do not noticeably affect the physical properties of the organism. This mean...
Do any painkillers block the burn of spicy food?	Yes. Nociception (pain) is blocked by acting on mu- receptors in the brain or periphery (also the gut which is often the cause of opioids induced constipation). This is high in the pathway, so even though capsaicin receptors (TRPV-1's) are separate than other "pain" receptors, the mechanism of opioids would still help...	[ "A number of vanilloids, most notably capsaicin, bind to the transient receptor potential vanilloid type 1 (TRPV1) receptor, an ion channel which naturally responds to noxious stimuli such as high temperatures and acidic pH. This action is responsible for the burning sensation experienced after eating spicy peppers...
how (in) effective is the "pull out" method as a form of birth control?	Can confirm. Have child because of this method.	[ "Coitus interruptus, also known as withdrawal or the pull-out method, is a method of birth control in which a man, during sexual intercourse, withdraws his penis from a woman's vagina prior to orgasm (and ejaculation) and then directs his ejaculate (semen) away from the vagina in an effort to avoid insemination.\n"...
The Taliban and the USA?	More of course can be said, but [this old response](_URL_0_) will likely be of interest for you.	[ "The Taliban () are a Sunni Islamic organization that operates in Afghanistan. It also refers to itself as Islamic Emirate of Afghanistan. The Taliban emerged in 1994 taking advantage of the power vacuum that was left following the aftermath of the Afghan Civil War Mapping Militant Organizations. The group was main...
why do we keep discovering ancient artifacts and why are they so rare? wouldn't the world have accumulated mass amounts of stuff over 1000s of years and be common to find?	Things break down and more importantly tend to be reused by descendants. While that piece of Roman armor might be precious today, in the ancient world it was just Grandpa Flavius' old helmet, and we really needed to make a new plow, so we'd smelt it down.	[ "Weapons and armor, designed to be sturdy, tended to last longer than other artifacts, and thus a great deal of surviving artifacts recovered tend to fall in this category as they are more likely to survive. Weapons and armor were also mass-produced to a scale that makes them quite plentiful throughout history, and...
Siberia is vast. Prior to the railroad and telegraph, how did Imperial Russia govern such a large area?	Well, they didn't. As you intimate, it required the railroad to govern effectively. They controlled pockets all the way to the Pacific by the mid-1600s or so, but they didn't establish direct control over the majority of Siberia until the establishment of the Trans-Siberian Railroad, constructed from 1891 to 1916. Is ...	[ "During the Russian Empire, Siberia was chiefly developed as an agricultural province. The government also used it as a place of exile, sending Avvakum, Dostoevsky, and the Decemberists, among others, to work camps in the region. During the 19th century, the Trans-Siberian Railway was constructed, supporting indust...
What is happening in your body when you are recovering from a cold?	The immune system is very complicated but hopefully this should help with some of the basics: Your immune system has 2 major parts, there are the "innate" defences like enzymes in saliva and some cells like macrophages that destroy intruders and then there is a more specialised "adaptive" part which is more relevant h...	[ "When cold, the body attempts to capture heat in the blood by constricting the smooth muscle cells around the microvasculature. The muscle cells are constricted by an increase in calcium. The decreased cross-sectional area for flow increases the vascular resistance and lowers the flow to extremities. This mechanism...
how does the anti-shoplifting system in a supermarket work?	It’s these stuck on thing that have a slight magnetic field to them the get activated when you walk through the thing that beep.	[ "Some supermarket chains allow customers to scan their own groceries with handheld barcode readers while placing them in their own carts (see self-checkout). While the system gives customers the ability to place groceries in their bags without paying, and customers can be randomly audited, participating supermarket...
Is there a rating scale for bolts of lightning? What conditions would cause massive singular strikes of lightning instead of many smaller ones?	Yes! Lightning has vastly different strengths that are typically measured in the peak electrical current of the lightning. There are few other measures such as the charge-moment change (how much electrical charge is moved by the lightning), radiated energy (how much radio waves it gives off), or optical power (how br...	[ "The three main kinds of lightning are distinguished by where they occur: either inside a single thundercloud, between two different clouds, or between a cloud and the ground. Many other observational variants are recognized, including \"heat lightning\", which can be seen from a great distance but not heard; dry l...
When doctors get a positive result, do they automatically run the test again to rule out false-positives?	Depends on how accurate the test is, how much it costs, how likely you're to really be afflicted, whether they can run a better test, and how dangerous the condition actually is.	[ "In order to reduce the problem of false positives, a test should be very accurate in reporting a \"negative\" result when the patient does not have the disease. If the test reported a negative result in patients without the disease with probability 0.999, then\n", "A false positive result does not indicate a con...
why would a railgun be better than a regular cannon?	A few reasons: 1) muzzle velocity. The theoretical speed of a projectile is much greater, providing better range, accuracy, and penetration. 2) projectile size and cost. Using EMF to launch a projectile instead of gunpowder dramatically shrinks the inventory of firing charges and shells you need to keep on a ship. ...	[ "Current railgun technologies necessitate a long and heavy barrel, but a railgun's ballistics far outperform conventional cannons of equal barrel lengths. Railguns can also deliver area of effect damage by detonating a bursting charge in the projectile which unleashes a swarm of smaller projectiles over a large are...
Which is the history of the beginning of this sub	As it happens, one of the mods, /u/agentdcf, wrote a paper about the beginnings of the sub - [You can read it here.](_URL_1_) I'm also trying to find a post that's an interview by the Reddit admins of our subreddit's founder, /u/artrw, not long after the sub was created. The hunt continues... edit: well.. I've searc...	[ "BULLET::::- February 1, 854 : The new era name was created to mark an event or series of events. The previous era ended and the new one commenced in \"Ninju\" 4, on the 29th day of the 11th month of 854.\n", "BULLET::::- February 6, 1144 : The new era name was created to mark an event or series of events. The pr...
why are consoles/phones so limited at launch and sold out for a while after? these are huge companies, it seems they could supply as much as needed.	Almost all consoles come out selling at a loss - meaning, it costs them more to make the console than they actually make back from selling it. Over time, the cost of producing the console's parts goes down (as they're relatively older), so it's more cost-effective for them to wait a little longer to meet the demand.	[ "However, the UK company's lack of capital to invest in the machine's manufacture meant that the cosmetic appearance of the computer left a lot to be desired. Furthermore, the machines were extremely costly – IBM's new Personal Computer/AT was shipping at about half the price SDS UK Limited needed to sell their com...
why do most people need complete silence to sleep?	Because they cannot sleep with noise.	[ "Sleep-talking by itself is typically harmless; however, it can wake others and cause them consternation—especially when misinterpreted as conscious speech by an observer. If the sleep-talking is dramatic, emotional, or profane it may be a sign of another sleep disorder (see above). Sleep-talking can be monitored b...
why would an automaker choose an inline 6, v6, or horizontally opposed 6 cylinder engine?	A lot of it is habit and tradition. BMW for example has always done I6s not V6s and continue to do so. American automakers do V6s in part because the first ones were made by removing two cylinders from V8s. That got them into doing V6 engines and they have stuck with that mostly. There are some advantages and disadva...	[ "The inline-four engine is the most common four-cylinder configuration, whereas the straight-6 has largely given way to the V6 engine, which although not as naturally smooth-running is smaller in both length and height and easier to fit into the engine bay of smaller modern cars. Some manufacturers, including Acura...
why do 3rd party booking sites (agoda, booking etc.) have cheaper rates than the hotel itself? and why does the hotel price match the rates on the 3rd party booking sites?	The hotel doesn’t want to insult the guests that paid full price and make them feel like they’re getting ripped off. Unrented rooms are a waste. There still going to exist whether occupied or not. As long as the revenue received is greater than the cost of operation (maids, electricity water gas etc) any money made...	[ "In April 2015, French, Swedish and Italian competition authorities accepted a proposal by Booking.com to drop its \"rate parity\" clause and thereby allow competitor travel agents to offer lower hotel prices than Booking.com. Booking.com further agreed to extend and apply its proposal across all EU states Hotels a...
how can facebook identify people in photos before they're tagged, but computers have difficulty recognizing other objects in a photo?	You've misinterpreted those captchas as something that computers are never able to do In fact, they've identified millions and possibly billions of windows and street signs. The ones that it gives you are the weird ones that have tripped up the algorithm and it wants a second opinion on. Bots are unlikely to be ab...	[ "The uploading of scanned or photographed identity documents is a practice in use, for example at Facebook. According to Facebook, there are two reasons that a person would be asked to send a scan of or photograph of an ID to Facebook: to show account ownership and to confirm their name.\n", "Photo identification...
why technology develops in a somewhat linear order?	1) In the typical Moores law graph, the Y axis is not linear, thus the growth is not linear 2) What your describing is doubling and not really 'linear'. Going from a Commodore 64 (w/ 64K memory) in early 80's to a home computer with 8Gig Ram is 5 orders of magnitude. At that growth rate, computers in 2030 will have...	[ "A big advantage of small signal models is they can be solved directly, while large signal nonlinear models are generally solved iteratively, with possible convergence or stability issues. By simplification to a linear model, the whole apparatus for solving linear equations becomes available, for example, simultane...
What exactly causes your eyes to get glassy?	When you're tired, you may be experiencing dry eye which actually can make the eyes water. This tearing may increase reflectiveness which would make them appear glassy. If you have a fever it's possible that you also have a form of viral conjunctivitis as well which is associated with a watery discharge. Without more...	[ "The lack of nutrients in the diet, or the lack of a balanced diet, can contribute to the discoloration of the area under the eyes. It is believed that iron deficiency can cause dark circles as well. Iron deficiency is the most common type of anemia and this condition is a sign that not enough oxygen is getting to ...
How much did the world wars shake the religious faith of Europeans?	Can only provide a very limited answer but will give you what i know! In some circles it only solidified it, the wars showed the brutality of modernity, a project which was supposed to bring prosperity and peace. This distrust of modernity (and the science which came along with it) would have cemented religious belief...	[ "World War I, also known as the First World War or the Great War, had a major impact on global society and culture. Religion was also impacted. Christianity in both Europe and the United States served to unite fellow soldiers of the same denomination and motivated them to fight. Some European countries shared unity...
- how does amazon estimate delivery time?	Past experiences and logistics from past shipments.	[ "The service utilizes quadcopters to autonomously fly individual packages to customers within 30 minutes of ordering. To qualify for 30-minute delivery, the order must be less than 5 pounds (2.25 kg), must be small enough to fit in the cargo box that the craft will carry, and must have a delivery location within a ...
Is there a definitive text for the history of New York City?	For more recent NYC history, Thomas Kessner, Fiorello H. LaGuardia and the Making of Modern New York is great. I have not yet read Gotham: A History of New York City to 1898 by Burrows and Wallace, but it was highly recommended to me.	[ "The Encyclopedia of New York City is a comprehensive reference book on New York City, New York. Historian and Columbia University professor Kenneth T. Jackson edited this work that combines informative and interesting information about New York City into one volume, first published in 1995 by the New-York Historic...
why this goat faints.	Fainting goats aren't rare. They usually do it as a defense mechanism or a reaction to being scared, like a possum playing dead. For some reason, this goat is afraid of grass.	[ "The myotonic goat, otherwise known as the fainting goat, is a domestic goat that temporarily seizes when it feels panic. If startled by sudden movements or loud noises, they will attempt to escape from the disturbance, generally followed by a startle reaction. In more severe cases, this reaction results in strong ...
why is water a liquid?	The state of any given material is based mainly on the interaction between two different things: The amount of energy in a given amount of the substance, and the strength of the attraction between the molecules/atoms of the substance. The stronger the attraction between molecules, the more likely it will be in liquid, ...	[ "Liquid water is found in bodies of water, such as an ocean, sea, lake, river, stream, canal, pond, or puddle. The majority of water on Earth is sea water. Water is also present in the atmosphere in solid, liquid, and vapor states. It also exists as groundwater in aquifers.\n", "Pure substances that are liquid un...
why are "bad" drugs sometimes ingested through snorting or smoking, but never "real" drugs?	Some medical drugs are inhalants (many asthma and allergy drugs). Many other medical drugs are injectable. I imagine smoking and snorting are harder to control dosage with (how much are you inhaling versus letting escape into the atmosphere) and getting precise dosage is important when treating an illness.	[ "Steve Rudd in has stated in \"Drugs and the Bible: E, Shrooms, Cocaine, Crack, Marijuana\" that using \"illicit\" drugs is a form of sorcery. Jennifer LeClaire writing for \"Charisma\" magazine called the group \"blasphemous\".\n", "The environmental impacts caused by the production of illicit drugs is an often ...
Can someone explain the behavior of Superfluid Helium?	When all Helium atoms fall into their many-body–quantum-mechanical ground state, they can all move synchronously. So there is no friction between atoms, but there could still be friction between the superfluid and e.g. the walls of a tube. Friction implies the transformation of kinetic energy to heat. A superfluid is ...	[ "In 1938, Pyotr Kapitsa, John Allen and Don Misener discovered that helium-4 became a new kind of fluid, now known as a superfluid, at temperatures less than 2.17 K (the lambda point). Superfluid helium has many unusual properties, including zero viscosity (the ability to flow without dissipating energy) and the ex...
Is carbon dioxide uniquely able to make a beverage effervescent?	Draft Guinness is aerated with nitrogen as well as carbon dioxide, which creates less acidity and smaller bubbles. The yeast which create the alcohol in beverages also create carbon dioxide, just as the do in leavened bread, so carbon dioxide is the natural aerating gas for beer and sparking wine. Joseph Priestly creat...	[ "Liquid carbon dioxide is the liquid state of carbon dioxide, which cannot occur under atmospheric pressure. It can only exist at a pressure above 5.1 atm, under 31.1 °C (temperature of critical point) and above -56.6 °C (temperature of triple point).The properties of liquid carbon dioxide are the same as gas carbo...
what are vectors and scalars? what is magnitude in this context?	A scalar is basically just a number. E.g. I am moving at 30mph. 30 is a scalar. A vector is a scalar plus a direction. E.g. I am moving north at 30mph. Here, the 30 is the "magnitude" of the vector, and north is the direction.	[ "A scalar or scalar quantity in physics is a physical quantity that can be described by a single element of a number field such as a real number, often accompanied by units of measurement. A scalar is usually said to be a physical quantity that only has magnitude and no other characteristics. This is in contrast to...
Would photons emitted from a bioluminescent source allow plants to photosynthesise?	Depending on the photosynthetic mechanism at play, a certain wavelength of light is preferred. If the photon from the source has the right wavelength, I see no reason why the plant would care where it came from.	[ "Organisms that undergo photosynthesis initially absorb light energy through the process of electron excitation in an antenna. This antenna varies between organisms. Bacteria can use ring-like structures as antennas, whereas plants and other organisms use chlorophyll pigments to absorb photons. This electron excita...
How do you isolate a gene from one organism, and insert it into another?	It's actually pretty easy for some organisms, but much harder for others. I'll try to walk you through the process: First, we find a gene that we want "expressed" in another organism (probably non-pathogenic E. coli, the workhorse of molecular biology). Let's say we go looking in yeast genome (which is published onli...	[ "The next step is to isolate the candidate gene. The cell containing the gene is opened and the DNA is purified. The gene is separated by using restriction enzymes to cut the DNA into fragments or polymerase chain reaction (PCR) to amplify up the gene segment. These segments can then be extracted through gel electr...
how does a software input into a computer physically change a transistor	Engineer here, this isn't 100% the entire story, but it's ELI5. Software input doesn't change the shape, state, or move or do anything physical to a transistor. A transistor is just another component whose shape and material will manipulate the flow of electricity in a specific and predictable way, just like any other...	[ "An in-circuit emulator (ICE) provides a window into the embedded system. The programmer uses the emulator to load programs into the embedded system, run them, step through them slowly, and view and change data used by the system's software.\n", "Modern ECUs use a microprocessor which can process the inputs from ...
How "bulged" can a planet become?	Of the major planets in our Solar System, Saturn is the 'flattest' with a [flattening ratio](_URL_5_) of [1:10](_URL_4_). For faster rotational speeds, the equilibrium shape is a Jacobi (scalene or tri-axial) ellipsoid rather than the familiar Maclaurin (oblate) spheroid (Wikipedia: [Ellipsoid](_URL_1_)). The Kuiper B...	[ "For earth, most of the bulge is made of sea water and has no correction for rigidity, but its mass density is 0.18 the average earth mass density (1 g/cm vs. 5.5 g/cm), so formula_15. The literature uses a close value of 0.2 (formula_16 )\n", "The total mass of the Tharsis bulge is approximately 10 kg, about the...
why does the peanut butter in a reese's peanut butter cup have a different texture?	Oil and chocolate are quite buddy buddy and want to mingle together. Peanut butter contains peanut oil which makes it easier to spread. However, this oil will mix with the chocolate covering the peanut butter cup and cause the chocolate to get soggy and melt off. So, the peanut butter inside the cup is peanut butter wi...	[ "The two main types of peanut butter are crunchy (or chunky) and smooth (or creamy). In crunchy peanut butter, some coarsely-ground peanut fragments are included to give extra texture. The peanuts in smooth peanut butter are ground uniformly, creating a creamy texture.\n", "Peanut butter is included as an ingredi...
the 15(+) different logical fallacies.	Slippery Slope: If we allow this to happen, it will lead to this other (loosely/hardly related) thing happening! Hasty Generalization: I know I'm right despite having little or biased evidence! Post hoc ergo propter hoc: This happened after this, so it must've caused it! Genetic/Origins Fallacy: This...	[ "Formal fallacies do not take into account the soundness of an argument, but rather its validity. Premises in formal logic are commonly represented by letters (most commonly p and q). A fallacy occurs when the structure of the argument is incorrect, despite the truth of the premises.\n", "Whately divided fallacie...
in an election, how is a write in candidate determined and notified if he/she wins?	Most write-in campaigns that actually win are public and fairly well organized. To the best of my knowledge, there has never been a candidate that is simultaneously popular enough to win a write-in campaign, and unknown enough for officials to have difficulty establishing their identity. Theoretically it could happen...	[ "In closed list systems, each party lists its candidates according to the party's candidate selection process. This sets the order of candidates on the list and thus, in effect, their probability of being elected. The first candidate on a list, for example, will get the first seat that party wins. Each voter casts ...
What would 'pagan' mean in 1896?	Since it includes the term etc. and is listed alongside these other religions, is there a reason not to take the trivial "everything else" answer at face value? Practitioners of other religions, with Hindus being a particularly notable exception to the list given?	[ "The term pagan is not attested in the English language until the 17th century. In addition to \"infidel\" and \"heretic\", it was used as one of several pejorative Christian counterparts to \"gentile\" ( / ) as used in Judaism, and to \"kafir\" (, 'unbeliever') and \"mushrik\" (, 'idolater') as in Islam.\n", "Th...
what the heck is going on with r/hearthstone right now?	It's April first in some parts of the world (in the US in just a couple of hours). Thus this is some sort of April fools joke, the purpose of which has not yet been revealed.	[ "The \"Ashdown Weekend\" is a village event, begun in 1973 and serving to make money for different organisations in the village. It includes five-a-side football, a fete, vintage car show, barbecue, art exhibition, children's party, senior citizens' party, and an \"auction of promises\".\n", "\"#REHASH\" is the n...
why americans won't name their sons jesus?	We use Josh.	[ "While the exact origins of the phrase are unknown, it is commonly believed to have been coined by Americans during World War II. \"John\" was the most popular and common baby name for boys in America every single year from 1880 through 1923, making it a reasonable 'placeholder' name when denoting those of age for ...
tesla's worldwide wireless system and why did it fail.	It failed because of the inverse square law. Whenever you radiate something (sunlight, heat, or whatever) from a central point, the intensity decreases according to the square of the distance from that point. So, if you double the distance between you and the sun, the intensity of the light reduces to a quarter. Triple...	[ "The World Wireless System was a turn of the 20th century proposed telecommunications and electrical power delivery system designed by inventor Nikola Tesla based on his theories of using Earth and its atmosphere as electrical conductors. He claimed this system would allow for \"the transmission of electric energy ...
why former spanish and portuguese colonies replaced their languages with spanish and portuguese respectively but former british and french colonies didn't?	European colonization in the Americas started in the 16th century, opposed to African and Asian colonies which were established much later, under larger populations and a smaller interest in settlement. In less than a century, most indigenous American peoples were wiped out, along with their cultures. Still, during co...	[ "The Iberian languages Spanish and Portuguese were considered as one language not because their separate importance was in question, but because their linguistic roles in the modern world were similar.\n", "Spanish and English also have a long historical presence in Curaçao. Spanish became an important language i...
why isn't there a standard for microwave wattage?	A 1,000-watt microwave will cook quickly and efficiently. Microwaves with 700 watts or less are slower and may not cook evenly. In general, the higher the wattage, the faster the cooking time. However, Lower watts cost last and that's why they are out on the markets.	[ "The emitted power is regulated by norms (EIRP) both for cellular system and microwave. These microwave transmissions use emitted power typically from 30 mW to 0.3 W, radiated by the parabolic antenna on a beam wide round few degrees (1 to 3-4). The microwave channel arrangement is regulated by International Teleco...
Help Identifying WWII Army Ribbons	Top row: * [Purple Heart](_URL_1_), awarded for a wound received in combat against the enemy Bottom Row, L-R; * A severely faded or worn [American Campaign Medal](_URL_5_), awarded for being in the boundaries of the American Theater from 7 December 1941 until 2 March 1946, and; > * On permanent assignment outsid...	[ "Ribbons had printed patriotic messages which celebrated battles and important events, as well as royalty and the military leaders. They were designed by many famous German artists of the period. Most ribbons had the same size and followed the same design pattern with word \"\"!\"\" (\"\"Long live!\"\") printed on ...
How did Amazon cities disappear so quickly? (further detail inside)	I am going to assume you are referring to the Inca and Aztec civilisations of South America? In that case, I will plough ahead and give you a reasonable response for the fall of both empires. Firstly, it is important to note that these cities were very advanced and were praised as such, particularly in Hernan Cortés' ...	[ "On February 14, 2019, Amazon announced that it would cancel the planned Long Island City location due to opposition. The company also said that it would continue developing the Crystal City and Nashville locations. \"The New York Times\" reported that de Blasio and Cuomo were \"blindsided\" by Amazon's decision wh...
Who had the best/most wanted cigarettes during World War II? What about other products?	In Alamein: War Without Hate, both sides (German and British in North Africa) are shown to fetishise the supplies of the other side. Germans preferred English tea while English soldiers felt that German meat rations were superior, I believe, though I don't have the book to hand. The creation of a mythology of the oppon...	[ "The top-selling cigarette brands of the decade were Lucky Strike, Camel, Chesterfield, and Old Gold. That was the time of growth for the whole tobacco industry: again cigarettes were included in the soldier rations during World War II.\n", "Shortly before World War II, the brand's sales stagnated at less than 1%...
How does basic light reflection really work? Confused.	On an ideal conductor, the re-emitted photon has to cancel out the parallel component of the electric field. This results in a re-emitted photon that has to have the same momentum in the parallel component, and the opposite momentum in the perpendicular component. Or, the angle in equals the angle out.	[ "Reflection of light is either \"specular\" (mirror-like) or \"diffuse\" (retaining the energy, but losing the image) depending on the nature of the interface. In specular reflection the phase of the reflected waves depends on the choice of the origin of coordinates, but the relative phase between s and p (TE and T...
Is it possible for a male phenotype to somehow evolve into a female looking phenotype and vice versa?	XY is the genotype, phenotype is the observable characteristics. Are you asking if an XY genotype can develop a female phenotype? Yes, [androgen insensitivity syndrome.](_URL_0_)	[ "Phenotypic traits can be displayed in one sex and desired in the other sex, causing a positive feedback loop called a Fisherian runaway, for example, the extravagant plumage of some male birds such as the peacock. An alternate theory proposed by the same Ronald Fisher in 1930 is the sexy son hypothesis, that mothe...
how well-supported is the big bang theory? are we fairly certain it's true?	Yes, and overwhelmingly so. However, you have to be careful about what you mean when you say "Big Bang Theory", for it is not a theory about how the universe was created, but rather how it has evolved. Despite what anyone will tell you, we physicists currently have no idea how the universe was created.	[ "The Big Bang theory is the prevailing cosmological model for the universe from the earliest known periods through its subsequent large-scale evolution. Despite its success in explaining many observed features of the universe including galactic redshifts, the relative abundance of light elements such as hydrogen an...
why do so many sicknesses and diseases start with the basic symptoms? (fever, rash, headache, vomiting, etc.)	It's because those symptoms aren't something the disease does to your body, it's something your body does to the disease. Fever puts your immune cells in high gear and hampers some pathogens. Vomiting and diarrhea eject the contents of your gastrointestinal tract; because your body suspects it may be poisoned or cont...	[ "Some symptoms occur in a wide range of disease processes, whereas other symptoms are fairly specific for a narrow range of illnesses. For example, a sudden loss of sight in one eye has a significantly smaller number of possible causes than nausea does.\n", "Most diseases are caused by multiple processes. For exa...
if the universe is constantly expanding, why do the stars appear as if they haven’t moved?	Expansion of the universe occurs at extremely large scales. Far larger than even the entire Milky Way galaxy. All the stars you can see with the naked eye are relatively close by and within the Milky way. Expansion is simply not significant on this scale. Also it is not expanding outward from a *point of origin,...	[ "In addition to slowing the overall expansion, gravity causes local clumping of matter into stars and galaxies. Once objects are formed and bound by gravity, they \"drop out\" of the expansion and do not subsequently expand under the influence of the cosmological metric, there being no force compelling them to do s...
Where did the tradition of flying flags half-mast after a tragedy come from?	First recorded instance of a flag being flown at half mast was on the British ship Heart's Ease in 1612 when the captain was killed by a native during the voyage in search of the Northwest Passage. It seems likely that this was already a recognized symbol at the time. It is speculated that the flag was lowered to a...	[ "Historically, flags were flown at half-mast on the Commemoration Day of Fallen Soldiers which takes place on the third Sunday of May. Originally, flag was raised to the finial in the morning, displayed at half-mast from 10:00 to 14:00, and again raised to the finial for the rest of the day. In 1995, the 50th anniv...
why are there so many rules on the american flag?	Most customs regarding the American flag are not uniquely American, and are shared (in at least a similar form) with most countries of the world. For example, not flying the flag in darkness, flying it half-staff in mourning, or not letting the flag touch the ground or get dirty. However, Americans are known for their ...	[ "However, the Johnson majority found the lack of evidence for flag protection in the Constitution that necessitated the claim of \"uniqueness\" to counter indicate protection of the flag from free speech. They answered the \"uniqueness\" claim directly: \"We have not recognized an exception to [bedrock First Amendm...
How and Why did the Franks and Visigoths start speaking Romance Languages?	Well let's look at a case study in the opposite direction and then circle back. Britain. Britain was a more or less fully Romanized province of the Empire with its own Romance speaking population, form of Roman urban life, and unity within the broader Roman economic and political world. Then it wasn't. The why isn'...	[ "As a result of over 500 years of Germano-Latin bilingualism, many Germanic words became ingrafted into the Gallo-Romance speech by the time it emerged as Old French in AD 900. And after the Franks abandoned Frankish, the Old French they spoke tended to be heavily Frankish influenced, with a distinctively Frankish ...
what are the differences between a parliament, senate, assembly and so on?	These are names applied to legislative bodies, and the specific authority and structure varies with each version. There's no official definition of what a specific term requires. They may be quite powerful like the US Senate, or practically useless like the Iraqi Parliament during the Hussein regime.	[ "A legislative chamber or house is a deliberative assembly within a legislature which generally meets and votes separately from the legislature's other chambers. Legislatures are usually unicameral, consisting of only one chamber, or bicameral, consisting of two, but there are rare examples of tricameral and tetrac...
Was Einstein's theory of relativity necessary for nuclear weapons to be created?	Disclaimer: I'm a physicist and not an historian. So... Einstein was hugely influential in that he wrote to the president to warn him about the possibility that the Germans were building an atomic bomb, and this was a factor that resulted in the start of the Manhattan project. Regarding the impact of the theory of r...	[ "Several experiments predating Einstein's 1905 paper are now interpreted as evidence for relativity. Of these it is known Einstein was aware of the Fizeau experiment before 1905, and historians have concluded that Einstein was at least aware of the Michelson–Morley experiment as early as 1899 despite claims he made...
selfIs there a definitive book/encyclopaedia of Australian Indigenous history?	You might be interested in u/Reedstilt's recommendations [here,](_URL_0_) though they might not be what you wanted.	[ "The Encyclopaedia of Aboriginal Australia: Aboriginal and Torres Strait Islander history, society and culture, edited by David Horton, is an encyclopaedia published by the \"Aboriginal Studies Press\" at the Australian Institute of Aboriginal and Torres Strait Islander Studies (AIATSIS) in 1994 and available in tw...
why does heat aggravate the taste of spice? and cold the affects of menthol?	Because the chemical responsible for "spice" capsaicin, activates the same receptors that actual heat does, so when you add temperature heat to it, its magnified. Similarly, menthol activates the same receptors that actual cold does, again magnifying the effects when you expose it to both menthol and actual cold.	[ "Menthol's ability to chemically trigger the cold-sensitive TRPM8 receptors in the skin is responsible for the well-known cooling sensation it provokes when inhaled, eaten, or applied to the skin. In this sense, it is similar to capsaicin, the chemical responsible for the spiciness of hot chilis (which stimulates h...
Why have there been so many animals that are called harlequins?	The harlequin was a character in the Commedia dell'arte who traditionally wore a patchwork costume. So anything that has the characteristic of looking like a patchwork can be reasonably compared to a harlequin.	[ "There was an earlier \"Harlequins R.F.C.\" in Nairobi which was formed in 1923 when the Nairobi District team decided, because it had become too powerful, to split and create two clubs, Harlequins RFC and Nondescripts RFC. It seems likely that the two names were chosen either in concert or one as a tongue-in-cheek...
why does the cold virus survive longer on non-porous surfaces (stainless steel, doorknobs) than on porous surfaces (clothes, tissues) and skin?	Actually it depends on envelope status. A non-enveloped virus means that it is what we refer to as "hardy" so it could potentially survive equally as well on any of these surfaces, which we would then refer to as fomites--especially hardy viruses like the adenoviridae are even capable of surviving chlorinated pool wate...	[ "The norovirus can survive for long periods outside a human host depending on the surface and temperature conditions: it can stay for weeks on hard and soft surfaces, and it can survive for months, maybe even years in contaminated still water. A 2006 study found the virus remained on surfaces used for food preparat...
why do a lot of basement storage rooms/laundry rooms have a string to turn on the light but all other rooms use a light switch?	In the UK a lot of bathrooms still have a string. My understanding was that this was to avoid potentially wet hands touching a switch and causing an electric shock (very unlikely sure but still). As cellars can flood or are susceptible to damp could this factor be another consideration perhaps?	[ "Switches for lighting may be in hand-held devices, moving vehicles, and buildings. Residential and commercial buildings usually have wall-mounted light switches to control lighting within a room. Mounting height, visibility, and other design factors vary from country to country. The switch mounting boxes, or enclo...
how come when you're on a roller coaster you can feel how fast you're going, but on an airplane everything feels normal? [physics]	There are two things at play here. To start with we do not every feel how fast we are going, we feel the change in speed. When an airplane speeds up down the runway to take off you feel yourself getting pushed back into your seat. But once it is at a steady speed you no longer feel that. The other aspect is wind....	[ "The coaster train accelerates to its top speed in 5 seconds using a hydraulic launch system which generates a release velocity similar to that of steam catapults on an aircraft carrier. Riders experience up to 1.7 g of force during acceleration and up to 4.8 g throughout the ride. The roller coaster track is in le...
Why does rain have a smell before it starts to rain?	Petrichor (Greek ‘petra’ = rock / ‘ichor’ = ethereal fluid flowing in the veins of gods) was the name given to that smell by Australian scientists back in the 60’s. It’s the semi volatile compounds found in plant oils trapped in the soil and on the surface of rocks, metabolites of certain bacteria (geosmin as already m...	[ "The term was coined in 1964 by two Australian CSIRO researchers, Isabel Joy Bear and Richard G. Thomas, for an article in the journal \"Nature\". In the article, the authors describe how the smell derives from an oil exuded by certain plants during dry periods, whereupon it is absorbed by clay-based soils and rock...
Is the term "frequency" meaningless for a square wave because it consists of nearly infinite harmonics of some fundamental sinusoidal frequency?	It's not nearly infinite, it's actually infinite series. You can find the formula on [wiki](_URL_0_). Frequency isn't meaningless, because it's defined as number of occurrences per second. Square signal repeated x times per second makes perfect sense.	[ "The fundamental frequency, often referred to simply as the fundamental, is defined as the lowest frequency of a periodic waveform. In music, the fundamental is the musical pitch of a note that is perceived as the lowest partial present. In terms of a superposition of sinusoids, the fundamental frequency is the low...

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