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I found this old helmet in an antique store, and I was wondering where it is from.	Swedish M26 Army Helmet seems to be the one, _URL_0_ Heres some info on it. _URL_1_	[ "The Canterbury Helmet is an Iron Age helmet found in a field near Canterbury, Kent, England, in December 2012. Made of bronze, it is one of only a few helmets dating from the Iron Age to ever have been found in Britain. The helmet currently resides in the British Museum, and is undergoing conservation work. It was...
When/how did human started cooking?	The modern human gastrointestinal tract is evolved to digest cooked food. That takes a long time. Here is a peer reviewed article that argues that control of fire was achieved nearly two million of years ago by some of the first members of the Homo genus: _URL_2_ Because of the time needed for our current digestive...	[ "Phylogenetic analysis suggests that human ancestors may have invented cooking as far back as 1.8 million to 2.3 million years ago. Re-analysis of burnt bone fragments and plant ashes from the Wonderwerk Cave, South Africa, has provided evidence supporting control of fire by early humans there by 1 million years ag...
How long did it take a skilled armourer to make chainmail armour during medieval times?	My own area of study is the armour of high and late medieval Europe. So my answer will focus on that, not on the Early Middle Ages. I mention this caveat because the economics and social organization of Europe were very different between 600 and 1450, and this effected things like how armour was made, which in turn eff...	[ "During 12th century chainmail armour is first introduced in the Indian subcontinent and used by Turkic armies. An reference of chainmail armour was found in the inscription of Mularaja II and also at the Battle of Delhi where it was used by the armoured war elephants\n", "Chainmail was the prominent form of armo...
if utilities infastructure was created through taxpayer dollars, then why do people have to pay private companies for their utilities?	In most cases where facilities were built by the public and then privatized, the company either had to pay the government for the facilities, or agree to repair or improve the facilities at their own expense, thus effectively paying a bill that would have been the government's bill.	[ "Although utilities are regulated industries, they are typically privately owned and must therefore attract private capital. Accordingly, because of constitutional takings law, government regulators must assure private companies that a fair revenue is available in order to continue to attract investors and borrow m...
after accomplishing something very challenging why do we sometimes feel empty and emotionless about it immediately after?	Because the challenge is gone. Possibly.	[ "Emotionally unpleasant experiences have the tendency to come back and haunt us, even after frequent suppression. Such memories can be recovered gradually, through active search and reconstruction, or they can come to mind spontaneously, without active search.\n", "In time, emotional exhaustion may set in, leadin...
Does having houseplants at home provide any sort of measurable benefit to ones health?	[They can help reduce indoor pollutants](_URL_0_)	[ "The Healthy Homes program was made possible through a grant from the United States Department of Housing and Urban Development via a Healthy Homes Demonstration Program (HHD). The grant allows the Healthy Homes program to address environmental triggers that contribute to illnesses, conduct education and outreach t...
What is the difference between German Blitzkrieg strategy and Soviet Deep Battle doctrine?	First of all, the Germans never used the word 'Blitzkrieg' themselves and did not have a specific doctrine around deep penetration or strategic battle - as you can see from from them turning back from Warsaw to deal with the Polish counterattack at Bzura 1939-09-09, the halting of the armoured units in front of the Dun...	[ "During the 1930s, the resurgence of the German military in the era of the \"Third Reich\" saw German innovations in the tactical arena. The methodology used by the Germans in the Second World War was named \"\"Blitzkrieg\"\". There is a common misconception that \"Blitzkrieg\", which is not accepted as a coherent ...
[META] Wide-scale revisions to the official rules	> [W]hile this is a public forum it is not an egalitarian one; not all answers will be treated as having equal merit. Thank you for taking a clear stance on this issue and not pussy-footing around it. I come to this subreddit for content and there really is a very impressive panel of historians to provide that. As ...	[ "There are currently 44 rules, with the latest revision having been adopted on January 24, 2013. (The Legislative Transparency and Accountability Act of 2006 lobbying reform bill introduced a 44th rule on earmarks). The stricter rules are often waived by unanimous consent.\n", "The advanced rules have been period...
how can i help somebody with seasonal depression feel better?	Phototherapy is noted to help people with seasonal depression. It involves basically shining a special lamp in your indoor space to help mitigate the lack of light that comes with autumn & winter.	[ "A depressed mood is common during illnesses, such as influenza. It has been argued that this is an evolved mechanism that assists the individual in recovering by limiting his/her physical activity. The occurrence of low-level depression during the winter months, or seasonal affective disorder, may have been adapti...
what does the "crisper" drawer in my refrigerator do and what is the benefit to putting my veggies in there?	Actually, the crisper is the worst place to keep vegetables. They do better with air circulation and the temps higher in the fridge. The best thing to keep in the crisper are raw meats, primarily to prevent raw meat juices from dripping and contaminating anything else. The drawers are relatively easy to remove and sa...	[ "A crisper drawer (also known as a crisper) is a compartment located within a refrigerator designed to prolong the freshness of stored produce. Crisper drawers have a different level of humidity from the rest of the refrigerator, optimizing freshness in fruits and vegetables. They can be adjusted to both prevent th...
Can moons of dramatically different size happily co-exist?	There's nothing distinctively different between a planet's orbit around a star and a moon's orbit around a planet--there simply needs to be sufficient distance between them where "far enough" depends on the object's sizes. Even asteroids [can have moons.](_URL_0_) Essentially the question you need to ask is this, can...	[ "An intense search conducted by \"New Horizons\" confirmed that no moons larger than 4.5 km in diameter exist at the distances up to 180,000 km from Pluto (for smaller distances, this threshold is still smaller).\n", "Only the two largest regular moons have been imaged with a resolution sufficient to discern thei...
Do carbon based filters (such as brita) remove essential minerals that the human body needs?	First: Its important to note that Brita and similar water pitchers are not just an activated carbon pitcher. There is also an ion exchange resin present in the filter. Think of this ion exchange resin as working just like a water softener (that is, because it does work exactly like a water softener). Activated carbon ...	[ "Carbon ion therapy (CIRT) uses particles more massive than protons or neutrons. Carbon-ion radiotherapy has increasingly garnered scientific attention as technological delivery options have improved and clinical studies have demonstrated its treatment advantages for many cancers such as prostate, head and neck, lu...
why don't credit cards just use 19 digits instead of 16 digits plus 3 digit "security code"?	The CVV is separate from the card number, so if people record your card number (such as a card skimmer), they don't have access to the 3 digit security code. If you made it 19 digit, then 1 swipe and they have all they need to literally take all your cash.	[ "The international standard for financial services PIN management, ISO 9564-1, allows for PINs from four up to twelve digits, but recommends that for usability reasons the card issuer not assign a PIN longer than six digits. The inventor of the ATM, John Shepherd-Barron, had at first envisioned a six-digit numeric ...
why are the brussels and paris attacks so publicized and mourned over when others, like the current pakistani bombings, kill more and do more damage?	It's pretty much accepted that that part of the world is basically a warzone. Nobody's too surprised if something explodes or people die there. However if it happens in a modern major city, that IS a nasty shock. That kind of thing isn't "supposed" to happen in a "civilised area". Remember in the Dark Knight how the ...	[ "The perpetrators belonged to a terrorist cell which had been involved in the November 2015 Paris attacks. The Brussels bombings happened shortly after a series of police raids targeting the group. The bombings were the deadliest act of terrorism in Belgium's history. The Belgian government declared three days of n...
where and how does all the energy created by power plants get stored? or is the power being generated as it's needed?	The latter, mostly. In the case of plants that use some sort of fuel, the energy is already stored in whatever fuel that is being used. Generating energy from the fuel first, and then storing it back inside something else to be extracted later is a huge waste of everything. When you have too much power, you use les...	[ "Grid energy storage (also called large-scale energy storage) is a collection of methods used to store electrical energy on a large scale within an electrical power grid. Electrical energy is stored during times when production (especially from intermittent power plants such as renewable electricity sources such as...
Has anyone ever taught a computer to code?	You might be describing something a bit like [genetic programming.](_URL_0_) I believe these still require someone to determine the fitness of each program, but if you have some desired output and a set input, you can have something compare what the program produces to what you want the output to be and the algorithm w...	[ "The first computer codes were specialized for their applications: e.g., Alonzo Church was able to express the lambda calculus in a formulaic way and the Turing machine was an abstraction of the operation of a tape-marking machine.\n", "John Mauchly's Short Code, proposed in 1949, was one of the first high-level ...
Historically, how long have Arabs been the dominant ethnic group in the Middle East?	Unfortunately I don't think this an answerable question. "Arab blood" does not define Arabness. Arabness is at least partially a linguistically defined ethnicity. That's why dark-skinned dark-eyed [Anwar Sadat](_URL_2_) is just as much an Arab as light-skinned blue-eyed [Bashar al-Assad](_URL_0_) is an Arab. Aside fro...	[ "The earliest and most significant instance of \"Arabization\" was the first Muslim conquests of Muhammad and the subsequent Rashidun and Umayyad Caliphates. They built a Muslim Empire that grew well beyond the Arabian Peninsula, eventually reaching as far as Spain in the West and Central Asia to the East.\n", "A...
what exactly is that steamy-looking stuff that comes out right after a beer bottle is opened?	Water vapour condensed out of the air due to the sudden drop in pressure in the neck of the bottle would be my guess.	[ "\"Beer\" consisted of a cylindrical metal container in diameter and long containing seven or eight half-pint bottles. Each bottle was a SIP grenade - it contained white phosphorus, benzene, water and a strip of raw rubber, long, which dissolved and formed a layer. After a delay caused by a slow burning fuse, the m...
What would need to happen in order for it to be called the LAW of evolution?	There's nothing weak about the word theory. For instance, quantum field theory is the most accurate description of nature that we have. As for laws and theorems in physics: Bell's theorem Newton's law of gravity, laws of motion, law of heating and cooling Kirkchoff's laws Kepler's laws *Laws of thermodynamics...	[ "The statement is often misinterpreted as claiming that evolution is not reversible, or that lost structures and organs cannot reappear in the same form by any process of devolution. According to Richard Dawkins, the law is \"really just a statement about the statistical improbability of following exactly the same ...
why hockey refs fake a puck drop during a face off?	So that players who try to anticipate the drop and thus start their swing faster don't get an advantage. They are supposed to wait until the puck is dropped to start their swing.	[ "BULLET::::- In amateur ice hockey, intentionally icing the puck, lining up at the wrong face-off dot, or shooting the puck over the glass (in professional hockey, the team that ices the puck is not allowed a line change, while shooting the puck over the glass leads to a two-minute penalty).\n", "A team which sho...
why are cans in hawaii shaped differently than regular soda cans?	This is an older design of common cans. Let this guy shed some light on it in the most interesting can-related video ever produced: _URL_0_	[ "Cans come in a variety of shapes: two common ones are the \"soup tin\" and the \"tuna tin\". Walls are often stiffened with rib bulges, especially on larger cans, to help the can resist dents that can cause seams to split.\n", "The American mechanical engineer and inventor Nathaniel Wyeth first patented PET in 1...
Would an ancient Roman be able to read and understand the Latin Wikipedia?	Post this to r/latin--I think they'd get a kick out of it. :)	[ "Roman authors, such as Sallust, allude to some books written in the Punic language, but none have survived except occasionally in translation (e.g., Mago's treatise) or in snippets (e.g., in Plautus' plays). The Cippi of Melqart, a bilingual inscription in Ancient Greek and Carthaginian discovered in Malta in 1694...
how have members of the bush admin not been charged with committing war crimes yet?	This is bull they by definition did commi war crimes facts are not opinions	[ "Bugliosi argues that, under the felony-murder rule, the resulting deaths of over 4,000 American soldiers and 100,000 Iraqi civilians (as of spring 2008) since hostilities began can be charged against Bush as second-degree murder. He said that any of the 50 state attorneys general, as well as any district attorney ...
what does board mean in room and board?	If someone is offering "room and board", they are offering to house and feed you (generally). This sometimes is forgotten, but that's what it means.	[ "Room and board describes a situation where, in exchange for money, labor or other considerations, a person is provided with a place to live as well as meals on a comprehensive basis. It commonly occurs as a fee at colleges and universities; it also occurs in hotel-style accommodation for short stays.\n", "The \"...
If an atom emits a photon when an excited electron returns to ground state, can that happen without the atom being heated up?	There are many ways that can happen - basically every method of lighting that isn't incandescent light is an example. [Light-emitting diode](_URL_5_) uses electricity to push electrons to a high energy state, and at the junction the electron falls to a lower state and emits a photon. [Fluorescent lamp](_URL_11_) also...	[ "If the atom is in the excited state, it may decay into the lower state by the process of spontaneous emission, releasing the difference in energies between the two states as a photon. The photon will have frequency \"ν\" and energy \"hν\", given by:\n", "If an atom is already in the excited state, it may be agit...
Why did cavalry during the U.S. Civil War operate almost exclusively as dragoons?	> Yet both Union and Confederate cavalry corps operated almost exclusively as dragoons. Why was this? To what extent was this affected by the duties of pre-war US cavalry, and/or the lack of a European-style military establishment? The ways in which Union and Confederate cavalry came to operate during the war depen...	[ "Before the Civil War there was no light or heavy cavalry in the US army. Instead there were \"Dragoons\" (founded 1830) and \"Mounted Riflemen\" (founded c.1840). In 1861 these mounted regiments were renamed cavalry and given yellow piping.\n", "During the American Civil War (1861–1865), cavalry held the most im...
why do a lot of hentai and japanese porn use rape?	I would theorize it comes partially from the cultural status of women in japan as submissive beings that you can force your will on, and partially from the value of purity in the sense that a women wanting it is slutty. As a result you get a power fantasy of forceful men and an unwanting/pure woman. At least in hent...	[ "Traditional Japanese religions do not consider sex or pornography a moral corruption in the Judaeo-Christian sense, and until the changing morals of the Meiji era led to its suppression, shunga erotic prints were a major genre. While the Tokugawa regime subjected Japan to strict censorship laws, pornography was no...
Why can't the immune system prevent shingles outbreaks, since it already has antibodies for the virus?	My professor explained it as a cellular vs humoral immunity question. Antibodies do a great job of stopping spread in humors (blood, interstitial fluid, etc.) -- hence antibody immunity is called humoral immunity. But, Varicella Zoster Virus (VZV) survives in the nerve (dorsal root ganglia, to be specific), which is ...	[ "Unless the immune system is compromised, it suppresses reactivation of the virus and prevents shingles outbreaks. Why this suppression sometimes fails is poorly understood, but shingles is more likely to occur in people whose immune systems are impaired due to aging, immunosuppressive therapy, psychological stress...
At what altitude on earth is the air pressure roughly equivalent to the surface pressure of the Martian atmosphere?	> The surface pressure on Mars is equivalent to the range of pressures on Earth at altitudes between ~30 km and ~60 km. --[Math Encounters Blog](_URL_1_) > At altitudes above 50,000 feet [_15.2 km_] man requires a pressurized suit to be safe in this near space environment. --[A Brief History of the Pressure Suit...	[ "At about 28 miles (45 km, 150 thousand feet ) Earth altitude the pressure starts to be equivalent to Mars surface pressure. However, the major component of Mars air, CO gas, is denser than Earth air for a given pressure. Perhaps more significantly there is no land at this altitude on earth. The highest point on ea...
the core principles of immanuel kant's philosphy.	Kant answers 3 big questions: 1- what is reality? Kant says there's a real world outside of your body. But the way you experience this world (using your senses of seeing, hearing, touching etc.) creates a map, or model, of this outside reality in your mind, which is unique to YOU. Even things like space and time a...	[ "Immanuel Kant employs the term \"amphiboly\" in a sense of his own, as he has done in the case of other philosophical words. He denotes by it a confusion of the notions of the pure understanding with the perceptions of experience, and a consequent ascription to the latter of what belongs only to the former.\n", ...
How is nuclear radiation stored in objects?	Unstable nuclei will eventually decay and emit radiation. If something is bombarded with neutrons, some of them are captured by the nuclei, which can become unstable. In the case of water, it's possible that some could be captured to produce tritium, which is radioactive.	[ "Since nuclear materials are radioactive, it is important to ensure that radiation exposure of those involved in the transport of such materials and of the general public along transport routes is limited. Packaging for nuclear materials includes, where appropriate, shielding to reduce potential radiation exposures...
If we set off a nuke near Jupiters core....	No. Some fusion might occur but it would not be self-sustaining.	[ "\"Jupiter\" sank the on 17 January 1942. On 27 February 1942 she struck a mine laid earlier in the day by the as she steamed with the American-British-Dutch-Australian Command (ABDA) cruiser force during the Battle of the Java Sea. The destroyer sank off the north Java coast in the Java Sea at 21:16 hours. Initial...
why does squirting lemon juice over spicy food make it less spicy?	It does reduce the spice. Spicy chili peppers contain an oil called capsaicin which gives the spicy flavor. Lemon juice has acids in it, and the acids neutralize the oils, which reduces the spice.	[ "Astringency, the dry, puckering mouthfeel caused by the tannins in unripe fruits, lets the fruit mature by deterring eating. Ripe fruits and fruit parts including blackthorn (sloe berries), \"Aronia\" chokeberry, chokecherry, bird cherry, rhubarb, quince and persimmon fruits, and banana skins are very astringent; ...
if oil is ancient organic matter, then how is there so much of it?	Hundreds of millions of years of swamps doing swampy things... ...like sucking down carbon from the atmosphere and sinking it in anoxic environments where it turns to kerogen and then to fossil fuels. The Carboniferous period predated the Permian Triassic Mass Extinction Event —aka: The Great Dying— by laying down...	[ "Petroleum is a naturally occurring liquid found in rock formations. It consists of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds. It is generally accepted that oil is formed mostly from the carbon rich remains of ancient plankton after exposure to heat and pressure in...
what exactly is management consulting?	In short you're correct: a management consultancy does spend a lot of time investigating a company, then makes a number of recommendations to senior staff on how to improve their business. Not all management consultants are equal. The senior consultants and partners spend a lot of time with senior members of the compa...	[ "The practice of management consulting is about \"helping organizations to improve their performance, operating primarily through the analysis of existing organizational problems and the development of plans for improvement.\" with the purpose of \"gaining external (and presumably objective) advice and access to th...
Why didn't Israel keep the Sinai peninsular?	Because giving it up was a hugely important bargaining chip for peace with Egypt. No one really regarded it as part of Israel (the way the West Bank is), though there were people there who were less than thrilled about being kicked out. Making it demilitarized allowed for Israel to retain a buffer, while still gettin...	[ "The Egypt–Israel Peace Treaty led Israel to give up the Sinai Peninsula in 1982 and transform the military rule in the Gaza Strip and the West Bank into the Israeli Civil Administration in 1981. The Western part of Golan Heights was unilaterally annexed by Israel the same year, thus abolishing the Military Governo...
Reddit science people, my 6 year old would like an answer to a space question. I have no idea what to tell her.	Your daughter is in good company with that wondering. One of the very first scientists was a Greek guy named Thales, who held that the primary essence of every substance was water. What do you mean by "what if?" Do you mean "If the universe were all water, what would it be like?" Or do you mean "How do we know the ...	[ "Less than two weeks after the trip, she applied to study communication and electronic engineering at Monterrey Tech, graduating in 2003. Unfortunately, she was the only one at the school at the time interested in space. Despite this, she attended space conferences and other events such as the National Astronomy Co...
how do car dealerships work with the car companies and how do they make their profits?	Car dealerships are independent businesses who have franchise agreements with the various car makers they sell. They purchase the vehicles through the manufacturers at the invoice price, but there are often other mechanisms for the dealers to make money from the sale, such as manufacturer holdbacks, quota bonuses, and ...	[ "Car dealerships are usually franchised to sell and service vehicles by specific companies. They are often located on properties offering enough room to have buildings housing a showroom, mechanical service, and body repair facilities, as well as to provide storage for used and new vehicles. Many dealerships are lo...
Is there any proof that Mesopotamia and Egypt had contact with each other and if they did, what was their relationship like?	What timeframe are you refering to?	[ "The intensity of the exchanges suggest however that the contacts between Egypt and Mesopotamia were often direct, rather than merely through middlemen or through trade. Uruk had known colonial outposts of as far as Habuba Kabira, in modern Syria, insuring they presence in the Levant. Numerous Uruk cylinder seals h...
How much cytoplasm does the average animal cell contain?	About 100-1000 femtoliters. & #x200B; But it's a pretty hard thing to answer. The cell with the smallest volume that I know of is the sperm cell, with about 20 femtoliters (fL). The most numerous cell in your body is the red blood cell, and it has a cytoplasmic volume of about 100 fL. But a fibroblast has a volume o...	[ "The proportion of cell volume that is cytosol varies: for example while this compartment forms the bulk of cell structure in bacteria, in plant cells the main compartment is the large central vacuole. The cytosol consists mostly of water, dissolved ions, small molecules, and large water-soluble molecules (such as ...
why does it take so long for employers to reach hiring decisions?	Hiring an employee is a big investment. If there are lots of good options, then you want to make sure you're making the right one.	[ "Edmund Phelps [1972] introduced the assumption of uncertainty in hiring decisions. When employers make a hiring decision, although they can scrutinize the qualifications of the applicants, they cannot know for sure which applicant would perform better or would be more stable. Thus, they are more likely to hire the...
why is the senate investigating claims that facebook censors conservative news when facebook is a private entity/platform?	Because the senate doesn't give a shit about actual government duties and only cares about their own partisan political ideologies and abusing their powers as much as possible in order to advance those particular political ideologies.	[ "Claims of shadow banning of conservative social media accounts began in 2016 with Facebook’s “Trending News” controversy. Conservative news sites lashed out at Facebook after a report from an unnamed Facebook employee on May 7 alleged that contractors for the social media giant were told to minimize links to their...
How do Historians typically calculate an "exact" date?	hi! hopefully some of the historians in antiquities will drop by with more info, but you may be interested in a few related posts * [How do we know what years certain pre-gregorian historical events happened in?](_URL_4_) * [How certain are we of what year it is? Were there every any disagreements, like during the D...	[ "A calendar date is a reference to a particular day represented within a calendar system. The calendar date allows the specific day to be identified. The number of days between two dates may be calculated. For example, \"24 2020\" is ten days after \"14 2020\" in the Gregorian calendar. The date of a particular eve...
With the Norman Conquest of England in 1066, the English language began rapidly changing. What other long-term cultural changes did this event bring about within England?	Hi there, I essentially answered a similar question to yours [here](_URL_1_), and linked to an earlier answer on some more of the legal changes [here](_URL_0_). The legal changes in particular would have had a genuine impact on the day-to-day life of the English people, especially as the legal system turned heavily fro...	[ "After the conquest of England in 1066, the Normans's language developed into Anglo-Norman. Anglo-Norman served as the language of the ruling classes and commerce in England from the time of the conquest until the Hundred Years' War, by which time the use of French-influenced English had spread throughout English s...
Biologically, how does pedophilia even make sense?	Although what causes pedophilia is not yet known, beginning in 2002, researchers began reporting a series of findings linking pedophilia with brain structure and function: Pedophilic (and hebephilic) men have lower IQs, poorer scores on memory tests, greater rates of non-right-handedness, greater rates of school grade ...	[ "BULLET::::- Pedophilia is a psychological disorder in which an adult or older adolescent experiences a sexual preference for prepubescent children. According to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), pedophilia is a paraphilia in which a person has intense sexual ur...
why do black americans resent white americans so much for slavery when america wasn't the first to use slavery, and banned slavery 13 years before the last country to ban slavery did?	So in your world slavery was the end of the matter?	[ "The passage of the Thirteenth Amendment to the United States Constitution brought an end to the system of slavery that had kept American blacks in bondage since colonial times. After slavery was abolished, there was somewhat of a cultural crisis in the Southern states. Even though black Americans had received thei...
What books should be trusted?	Obviously, there is always a ton to be said on this sort of question, but you might find [this](_URL_0_) response by /u/Cosmic_Charlie informative	[ "The \"Los Angeles Times\" wrote that the author \"has given us a clear, almost controversial book that draws on the text and teachings of an ancient mystical faith and applies them to the concerns of contemporary life. His insights into the use of meditation to overcome the fear of death are comforting, reassuring...
Can light impart momentum?	The solar sail can either absorb the light (so the sail gains the momentum of the photon it asborbs), or better yet, reflect the light, reversing its momentum. By conservation of momentum, the sail then gains two times the photon's momentum. This is completely analogous to experiments you might do with, say, a medici...	[ "The angular momentum of light is a vector quantity that expresses the amount of dynamical rotation present in the electromagnetic field of the light. While traveling approximately in a straight line, a beam of light can also be rotating (or “\"spinning\"”, or “\"twisting\"”) around its own axis. This rotation, whi...
Why are the lanthanides and actinides crammed in one space?	They don't, it's just a,way of drawing the Periodic Table more compactly. If you wanted the table set out properly as a grid it would have to be an unwieldy long piece of paper. The whole thing really should be split at that point and the La and Ac elements inserted as two long lines. We draw it the way we do for for c...	[ "Lanthanum and actinium are commonly depicted as the remaining group 3 members. It has been suggested that this layout originated in the 1940s, with the appearance of periodic tables relying on the electron configurations of the elements and the notion of the differentiating electron. The configurations of caesium,...
How fast does an object inside the event horizon of a black hole move towards it?	There are two important things we have to remember here: 1. Velocity is a relative quantity. We can't just say, "That thing is moving at velocity v." We can only say, "That thing is moving at velocity v relative to that other thing." I assume you question is then, "Does an object inside the event horizon of a ...	[ "In the case of the horizon around a black hole, observers stationary with respect to a distant object will all agree on where the horizon is. While this seems to allow an observer lowered towards the hole on a rope (or rod) to contact the horizon, in practice this cannot be done. The proper distance to the horizon...
the difference in programming languages.	Every single programming language serves one purpose: explain to the computer what we want it to do. HTML is... not a programming language, it's a markup language, which basically means text formatting. XML and JSON are in the same category The rest of languages fall in a few general categories (with examples): 1. A...	[ "Just as different groups in software engineering advocate different \"methodologies\", different programming languages advocate different \"programming paradigms\". Some languages are designed to support one paradigm (Smalltalk supports object-oriented programming, Haskell supports functional programming), while o...
why do modern tvs seem to increase the framerate of video, even when to footage is decades old?	Modern televisions have a setting that is usually turned on by default that causes this effect. The way it does it is by looking at two frames in the image, seeing what the differences are, and "guessing" what another frame between the two would look like if it was there when the show was recorded. The TV then creates ...	[ "Conventional video displays consist of a series of images, or \"frames\", representing single snapshots in time. When the frames are updated rapidly enough, changes in those images provide the illusion of continuous motion. This makes normal television tubes unsuitable for computer displays, where the image is gen...
what exactly does a dip in economy do to a country?	If the economy dips less people are buying things, if less people are buying things then companies that make things can't afford to hire so many people to make those things. Those people lose their jobs and have less resources to buy things, and so on, and so on. Houses are lost because the bank expects you to pay m...	[ "These economic downturns occur because of increased supply and decreased demand, which combine to create a shift in surplus and power to the semi-periphery. Semi-periphery regions take advantage of the situation by expanding control of their home markets and the surrounding periphery countries at the expense of co...
why do helicopters crash so much more often than other aircraft?	Helicopters have extremely poor glide characteristics. Your best case scenario for a malfunction resulting in loss of lift is a controlled crash. There are a lot of flight regimes in which you're basically just 100% screwed in a helicopter because you simply don't have enough velocity or altitude to make any real recov...	[ "Of the accidents and incidents included in this list, six were caused by engine failure, while six flight-into-terrain accidents were recorded, with two additional hard landings resulting in serious damage to the aircraft. Seven more of the accidents and incidents were a result of problems in the helicopters' driv...
what are options and derivatives? and what are some of the more complex securities being traded?	A derivative is a contract you can buy and sell. For example, "whoever holds this piece of paper can buy 100 shares of IBM from me for $50 per share." Now, if IBM is worth a lot more than $50 a share, that piece of paper is valuable and you can sell it -- someone will pay good money for it, and its value fluctuates as ...	[ "This article covers those who deal in securities and futures in US markets. Securities include equities (stocks), bonds (US Government, corporate and municipal), and options thereon. Derivatives include futures and options thereon as well as swaps. The distinction in the US relates to having two regulators. Market...
Is it theoretically possible to replace all my bones (or most of the) for something made from a stronger material, like carbon fiber	Start by reading [this](_URL_0_) to learn about the functions of bone, which go beyond the structural.	[ "Bone generally has the ability to regenerate completely but requires a very small fracture space or some sort of scaffold to do so. Bone grafts may be autologous (bone harvested from the patient’s own body, often from the iliac crest), allograft (cadaveric bone usually obtained from a bone bank), or synthetic (oft...
if 1 and 0 (data) are voltage values, how is voltage stored in a flash drive after you plug it out of the computer and stop the electricity flow?	Think of it as balls and buckets. It takes energy to kick a ball into a bucket, and it takes energy to remove a ball from a bucket, but unless someone does something a ball outside a bucket will stay out, and if the ball is in it will stay in. Each bucket is a bit, and it's state (0 or 1) will be determined by whethe...	[ "For use in a binary digital computer, the tube had to be capable of storing either one of two states at each of its memory locations, corresponding to the binary digits (bits) 0 and 1. It exploited the positive or negative electric charge generated by displaying either a dash or a dot at any position on the CRT sc...
why can't i (besides being a dick to the postal service) drop off a letter in a mailbox, with the return address being my actual intended address, to avoid using a stamp?	You can. I have a friend who got caught, and was banned from the Postal Service for several years.	[ "Mailboxes, on the other hand, often have a \"maximum\" setback instead of a minimum one. A postal administration or postmaster may mandate that if a mailbox on a street is too far from the curb for the letter carrier to insert mail, without having to get out of the vehicle, the mail may not be delivered to that ad...
why people prefer mega or the pirate bay than mediafire?	I use TPB for a couple reasons. Number one is nostalgia. Number two is respect. They've been around for 10(?) years or so, name another pirating platform team that has faced the level of pressure TPB has...Mega, maybe? These guys are serving prison time and still running TPB. They've made plenty money and could have g...	[ "The Pirate Bay (sometimes abbreviated to TPB) is an online index of digital content of entertainment media and software. Founded in 2003 by Swedish think tank Piratbyrån, The Pirate Bay allows visitors to search, download, and contribute magnet links and torrent files, which facilitate peer-to-peer (P2P) file shar...
What is the oldest, civilized and still existing nation?	Depends on how you define "civilized" and "nation". 6th edition of Longman Dictionary of Contemporary English defines "civilized" as: "1. a civilized society is well organized and developed, and has fair laws and customs". In historical use, from what I remember, a civilized state has the following characteristics: ...	[ "The society is divided into 83 provinces along with six independent regions and ten dependent regions. On 1 January 2007, members served in 112 nations on six continents with the largest number in India and the US. Their average age was 57.3 years: 63.4 years for priests, 29.9 years for scholastics, and 65.5 years...
What is the history of course and grounds upkeep at St. Andrews?	St Andrews was unusual in that between 1552 and 1805 they used rabbits. There was a financial incentive for this, because rabbiting was a huge industry when every part of a rabbit had a use and there was always an increasing supply. This benefitted both the landlords who sold on the rabbits and the commoners who caught...	[ "The Charleston Trust is a charity set up in 1980 to restore and maintain the home of the Bloomsbury Group artists for the benefit of the public. The unique collection at Charleston is illustrative of the art and lifestyle of the influential Bloomsbury Group and has been on show to the public since 1986. Charleston...
Could Russia ever have won the Cold War?	In his book, Predicting Politics, political scientist Bruce Bueno de Mesquita simulates the Cold War as a battle over ideology between different countries. He allows the salience of foreign policy to vary randomly in each run of the simulation; military, economic, and demographic capabilities are set at the outset...	[ "In January 2017, a former US Government adviser Molly K. McKew said at \"Politico\" that the US would win a new cold war. \"The New Republic\" editor Jeet Heer dismissed the possibility as \"equally troubling[,] reckless threat inflation, wildly overstating the extent of Russian ambitions and power in support of a...
why are there fourteen mountains over 8,000m, but none over 9,000m?	It's likely Mt. Everest is near to the largest size mountain earth will support. A larger mountain is more massive, which puts a strain on the material at its base. They deform the plates they sit upon, more mass will further the deformation. And depending on height and climate, can promote glacial development, which i...	[ "Thirteen of the fourteen 8,000m summits are Ultras (the exception being Lhotse), and there are a further 64 Ultras over in height. There are 90 Ultras with a prominence of over , but only 22 with more than prominence.\n", "The list contains 451 mountains with a prominence higher than 300 m, among which 24 are ab...
why is "the big crunch" an unpopular theory?	So you have this balloon hooked up to an air compressor. Youre watching this and you see its slowly getting bigger. We know its getting bigger because if we draw a bunch of dots on the balloon with sharpie, you notice all the dots are getting farther from eachother. The big crunch says that this air compressor will tu...	[ "The Big Crunch is a theoretical scenario for the ultimate fate of the universe, in which the expansion of the universe eventually reverses and the universe recollapses, ultimately causing the cosmic scale factor to reach zero, an event potentially followed by a reformation of the universe starting with another Big...
Why did Japan have oil problems dispite owning oil-rich provinces during WW2?	There are basically three elements to this. First. While the the Southern Resource Area was oil rich by Japanese standards it was significantly less productive than other areas of the world at the time. In 1940 while the US produced 183 million tons of crude, the Dutch East Indies produced 8 million tons of crude. Th...	[ "Japanese oil fields in Sakhalin and Formosa provided only about ten percent of the petroleum needed to sustain Japanese industry. Reserves of California crude oil at Japanese refineries would have been exhausted in less than two years at the rate of consumption when United States terminated exports to Japan on 26 ...
if millipedes have around 200 legs and are that little then why are they so slow?	If you had to organise 200 legs you'd be slow, too.[1] Actually - some centipedes are very speedy, because that's the niche they've evolved to fit, but millipedes aren't predators (that I know of) and have no need for speed. [1] Actually, they're self-organising - each segment responds in a set way to the movement of...	[ "Octopuses mainly move about by relatively slow crawling, with some swimming in a head-first position. Jet propulsion, or backwards swimming, is their fastest means of locomotion, followed by swimming and crawling. When in no hurry, they usually crawl on either solid or soft surfaces. Several arms are extended forw...
how is it humanly possible to survive a flight in an airplane wheel well given the lack of heating, pressure ond oxygen, which are vital for survival at a high altitude?	Luck. The young man in question was unconscious for most of the trip, luckily for him, but he was certainly dicing with death. Stowing away in a wheel well isn't a surefire way to kill yourself, but this risk is certainly unacceptably high. There's just enough oxygen and heat -- and plenty of pressure -- up there to m...	[ "The newest models of aircraft were capable of exceeding altitudes at which humans can breathe, even with 100% oxygen supplementation, introducing the risk of hypoxia. Bird discovered that an oxygen regulator in a crashed German bomber he was ferrying back to the U.S. for study seemed to contain a pressure breathin...
when did the united states do away with voting as a "legal" holiday?	It's a holiday under state law in a handful of states, but it has never been a national holiday. The problem with making it a holiday or having voting on the weekend is that there will still always be people who have to work. If the law mandated that everybody had the day off, then emergency services like police and ho...	[ "In 1939, William Randolph Hearst advocated, through his chain of daily newspapers, the creation of a holiday to celebrate citizenship. In 1940, Congress designated the third Sunday in May as \"I am an American Day.\" In 1944 \"I am an American Day\" was promoted through the United States Immigration and Naturaliza...
Is blood pressure related to blood viscosity	The formula for blood pressure is: Heart rate • Stroke volume • Systemic vascular resistance * Heart rate = how many times the heart beats in 1 minute. * Stroke volume = how much blood is ejected from the heart each time it beats. * Systemic vascular resistance = the resistance to blood flow caused by the blood...	[ "Blood viscosity is a measure of the resistance of blood to flow. It can also be described as the thickness and stickiness of blood. This biophysical property makes it a critical determinant of friction against the vessel walls, the rate of venous return, the work required for the heart to pump blood, and how much ...
what thoughts go on in the mind of a typical mentally handicapped person?	There is no such thing as a "typical mentally handicapped person". Every individual is different and the brain is an extremely complex organ and development or injury affects every individual in different ways. A "mental handicap" may manifest completely different in two people depending on nature and/or nurture.	[ "Mental health and stability is a very important factor in a person’s everyday life. Social skills, behavioral skills, and someone’s way of thinking are just some of the things that the human brain develops at an early age. Learning how to interact with others and how to focus on certain subjects are essential less...
during the cold war, what's the point of splitting berlin? like, it seemed like a bad idea from the start?	It wasn't split during the cold war. It was split 4 ways after the Germans surrendered in WWII, into the Russian, American, English, and French zones. The idea behind splitting Berlin was that the allied powers defeated Germany, and thus each should be responsible for a section of the German capital.	[ "At first, this arrangement was intended to be of a temporary administrative nature, with all parties declaring that Germany and Berlin would soon be reunited. However, as the relations between the Western Allies and the Soviet Union soured and the Cold War began, the joint administration of Germany and Berlin brok...
What location does fat get used to create energy?	Ok so fat is called a Triglyceride or TAG and it is called that because it is made of three fatty acid chains. This structure is very stable and is unsoluable and is stored in docks called adipose tissue. When the body runs out of glucose and glycogen as fuel it starts burning fatty acids. A number of things need to ha...	[ "Fat is an important foodstuff for many forms of life, and fats serve both structural and metabolic functions. They are a necessary part of the diet of most heterotrophs (including humans) and are the most energy dense, thus the most efficient form of energy storage.\n", "Adipose tissue, commonly known as fat, is...
How can scientists measure the mass of an atom, and other subatomic particles to such extreme precision?	Particle masses can be measured in a few ways. Typically, subatomic particle masses are determined by the relationship between their energy and their momentum. If a particle is not moving, its total energy is E=mc\^2. If it is moving, then E\^2=(mc\^2)\^2+(pc)\^2, where p is the momentum and c is the speed of light. On...	[ "Since the electron mass determines a number of observed effects in atomic physics, there are potentially many ways to determine its mass from an experiment, if the values of other physical constants are already considered known.\n", "Typically, the mass of objects is measured in relation to that of the kilogram,...
why dont people have a problem with cuba being a problem?	There isn't a sort of flicked switch between free and oppressive. As countries go, Cuba isn't that bad. It's also poor, yes, but arguably because of US-imposed trade embargoes. All the money it spends on medical aid is also a very good PR move - it sends hundreds of doctors to developing countries. It also has ...	[ "Furthermore, Cuba has little to offer the United States economically. From the United States viewpoint, Cuba's one party semi-dictatorial form of government is especially undesirable due to characteristics such as its crackdowns on religious freedom, repression of the press, and repression of almost all criticism ...
What would be the implications if the existence of a magnetic monopole was found?	First, the existence of a magnetic monopole would imply the necessity of electric charge quantization -- the phenomenon that all electric charges are integer multiples of some fundamental charge, a property which is observed but for which we do not have a confirmed explanation. Secondly, many unified theories imply th...	[ "Modern interest in this concept stems from particle theories, notably Grand Unified Theories and superstring theories, that predict either the existence, or the possibility, of magnetic monopoles. These theories and others have inspired extensive efforts to search for monopoles. Despite these efforts, no magnetic ...
To what extent were the Romans successful against Persian horsemen?	So I wrote a post on why horse archers were so effective a couple of days ago: _URL_0_ As for Roman tactics against them, let's first look at Crassus' campaign. He was a rich man but a horrible commander, and actually was given a good route for his campaign. The King of Armenia offered him safe passage and extra cava...	[ "The Romans retired their frontier troops and the Persian forces susequently crossed the Tigris river. Shapur's tactic was to tire the Roman forces with a long march in the hot hours of the day before engaging them with his archers and cataphracts, thus, when the two armies came face-to-face, the Persian cavalry fe...
How accurate is Battlefield 1?	There's always room for discussion, but perhaps this previous topic found through the search function will answer your inquiry. * [Battlefield 1 Trailer Accuracy](_URL_0_)	[ "There is no serious historical evidence giving an exact place or time to the battle, nor any troop positions, numerical statistics, casualties, or much of anything of that nature. It is not even fully understood if the battle was in of itself a major engagement or merely a small battle or even a large skirmish. Di...
why did we shoot people that contracted rabies? (context within)	1. you're gonna die, and pretty soon, and it's incredibly painful. 2. you are likely to go nutso as the disease progresses and then bite someone, scratch someone or exchange fluids with them someone - you're contagious. In days of yore we took slightly more drastic approaches to dealing with this sort of thing....	[ "BULLET::::- Rabies, a fatal neurologic disease in animals and people, is caused by a virus. Animals and people are most commonly infected through bites from rabid animals. Infected cats may have a variety of signs, but most often have sudden behavioral changes and progressive paralysis.\n", "BULLET::::- Rabies –...
Were the Vandals any more destructive than other invading tribes during the fall of the Roman Empire, or was there another reason their name became connected with vandalism?	I'll only speak for one aspect of the Vandals in that, while certainly proving to be just as if not more destructive than the Huns and Alaric's visigoths--in terms of the sack of Rome they actually proved to be far less Vandal-like. Like when Attilla and the Huns were at Rome's doorstep, Pope Leo I once again rode ou...	[ "The Vandals were also weakened by the hostility of their Roman subjects, the continued existence among the Vandals of a faction loyal to Hilderic, and by the ambivalent position of the Moorish tribes, who watched the oncoming conflict from the sidelines, ready to join the victor and seize the spoils.\n", "The mo...
The negative side of the square root does not matter?	The square root symbol is just an object that we made up to keep track of certain quantities. The equation x^(2)-A=0 has two solutions in the real numbers for A > 0. Luckily we know that if x=b is a solution (so b is a number so that b^2=A), then x=-b is also a solution. This says two things: 1) We just need to know ...	[ "No square root can be taken of a negative number within the system of real numbers, because squares of all real numbers are non-negative. The lack of real square roots for the negative numbers can be used to expand the real number system to the complex numbers, by postulating the imaginary unit , which is one of t...
why are people scared of guns?	I get hunting, and have fired weapons myself (including a 20-gauge when I was a teenager, as well as a South African "R5" 5.56mm assault rifle on a range). So I don't "hate" guns, nor am I "scared" of them, but I still have major issues with the whole concept, philosophically. Step back a bit and look at the big pictu...	[ "In studies of nonfatal gun use, it was found that guns can contribute to coercive control, which can then escalate into chronic and more severe violence. Guns can have a negative impact on victims even without being discharged. Threats of gun use or showing a weapon can create damaging and long-lasting fear and em...
How many photons from a distant star hit the Earth at any given moment or per second, and does a unique photon strike every (very small) unit area of the side of the planet that faces the source?	> I was wondering if two people standing next to one another see distinct photons Any time you and another person see the same thing, you are actually seeing distinct photons. When you see something, it means photons from that object have been absorbed by your retina; the same photon can't be absorbed by the retinas...	[ "If we assume a 10 m diameter ideal ground-based telescope and an unresolved star: every second, over a patch the size of the seeing-enlarged image of the star, 35 photons arrive from the star and 3500 from air-glow. So, over an hour, roughly arrive from the air-glow, and approximately arrive from the source; so th...
how come women begin being biologically capable of having babies at an age (periods can start as early as 9) in which they are not developmentally/emotionally/physically capable to?	I see a lot of people mentioning evolution. Valid to some point. But a huge influence are endocrine disruptors like BPA. A few decades ago it wasn't common for girls as young as 9 to get their period. The chances of surviving a birth as a 9 year old are also pretty low.	[ "Precocious puberty can make a child fertile when very young, with the youngest mother on record being Lina Medina, who gave birth at the age of 5 years, 7 months and 17 days, in one report and at 6 years 5 months in another.\n", "These young girls, some as young as 12, are being force into sexual relationships w...
How prevalent was Latin in Britain under the Romans and if it was when did it die out as a common language?	We can't know for sure, but it was probably somewhat similar to English in India: it was a language of administration and law, a literary language, and a common language, particularly in the towns. Unfortunately we just don't have enough writing from Britain to know for certain.	[ "With the end of Roman rule, Latin was displaced as a spoken language by Old English in most of what became England during the Anglo-Saxon settlement of the fifth and sixth centuries. It survived in the remaining Celtic regions of western Britain until about 700, when it was replaced by the local Brittonic language...
I'm looking for books focused on political history (preferably books focused on the 20th century, but I'm open to anything). Any suggestions?	I can only give limited advice about The Rise and Fall of Communism as I just skimmed through a few pages of the book in a local Barnes and Noble but it seems to be a well-written book; however, I would also suggest you look at another book about communism that came out not too long ago called *The Red Flag: A Histor...	[ "The Century is a book about politics, philosophy and literature by Alain Badiou, first published in French by Éditions du Seuil in 2005; the English translation by Alberto Toscano was published by Polity Press in 2007. The thirteen chapters of the book are presented as lessons derived from a seminar Badiou gave at...
Why do people with chromosome abnormality/ disorder have shorter life expectancies than people without?	Defects typically worsen things and do not improve them. Some defects have more negative effects than others. That is a matter of statistics. In very rare cases, anomalies turn out to be no "defects" but improvements, but the statistical probability for this is very low. So bottom line: If you introduce a random cha...	[ "Twin studies have estimated that approximately 20-30% the variation in human lifespan can be related to genetics, with the rest due to individual behaviors and environmental factors which can be modified. Although over 200 gene variants have been associated with longevity according to a US-Belgian-UK research data...
You're in a stopped car with the windows closed, a horsefly is 'hovering'; Upon accelerating the car, does the fly remain in the same position in space, or does it hit the rear window?	A fly's motion is based on the objects it is in contact with, as well as the gravitational pull of the Earth. A fly would be hovering because the force exerted upwards by the air on the fly's wings is balanced out by the gravitational pull of the earth. Now, if the car were to accelerate, it would bring all of the ai...	[ "Each side of the body must be synchronized and the two sides are also coupled. That is, the left and right wings and thus the left and right halteres always beat at the same frequency. However, the amplitude of the wingbeat does not always have to be the same on the left and right side. This is what allows the fli...
Does heat energy have "momentum"?	No. Heat may continue to diffuse through the object, which may cause it to appear to be increasing in heat for a short while (e.g. if you're measuring temperature at a different spot from where it's being heated) but the max temperature wouldn't rise without a heat source.	[ "The concept of energy emerged from the idea of \"vis viva\" (living force), which Leibniz defined as the product of the mass of an object and its velocity squared; he believed that total \"vis viva\" was conserved. To account for slowing due to friction, Leibniz claimed that heat consisted of the random motion of ...
why does curiosity often outweigh common sense?	I think it might have to do with our hunter gatherer ancestors. We have a need for knowledge of everything near us, so we can be aware of predators, food, and other things either beneficial or detrimental to our survival.	[ "Although the phenomenon of curiosity is widely regarded, its root causes are relatively unknown beyond theory. However, recent studies have provided some insight into the neurological mechanisms that make up what is known as the reward pathway which may impact characteristics associated with curiosity, such as lea...
how do the machines work that the tsa use to put swabs in after they swipe your clothing?	They use a technique called "ion-mobility spectrometry". What happens is they ionize the specimen swabs and then travel through a tube with an electric field and a buffer gas that opposes the motion. The speed at which it will pass through the tube indicates what the material is made of, and it is calibrated to trigger...	[ "The user clips the piece of clothing on two hooks and the item is pulled into the machine. Then a series of rollers and arms moves in all directions to straighten and fold it. The machine can fold shirts, tops, trousers and dresses, but not small pieces of clothing like underwear or large items like sheets. The fo...
Why don't we have infinite entropy in the universe?	Entropy increases over time. It's a fundamental law of thermodynamics. However, the universe in it's current state isn't infinite, it had a start at the Big Bang. At the Big Bang, the universe had an incredibly low entropy. Why this is isn't entirely known, and there's a lot of speculation on the topic. We currently e...	[ "Max Planck wrote that the phrase \"entropy of the universe\" has no meaning because it admits of no accurate definition. More recently, Grandy writes: \"It is rather presumptuous to speak of the entropy of a universe about which we still understand so little, and we wonder how one might define thermodynamic entrop...
why it’s so uncomfortable to stare into someone else’s eyes for too long?	It depends who it's for. Alot of the time it's a show of dominant behavior or even submissive depending on the person. This can lead to people being uncomfortable. Other times for fewer people it's the start of a soul gaze, which is something most tend to avoid.	[ "Visually, a glaring person tends to have their eyes fixed and heavily focused on a subject. This can sometimes be considered synonymous to staring but, in most of the cases, staring is caused due to curiosity and lasts only for a short duration, whereas glaring is caused due to contempt and lasts for a relatively ...
why is it acceptable for politicians to litter signs and pamphlets everywhere?	You can't stop people from mailing you stuff or leaving it at your house but most towns have regulations around those signs that they leave on people's lawns. My town has these regulations: \- Need to get an owner's consent to put a sign on their lawn. \- Person needs to track where they put them. Candidates are r...	[ "In addition, it gives the requester a placebo effect of doing something substantive, while not actually volunteering to help their candidate. Critics charge that \"lawn signs don't vote\" and dismiss their importance. Theft of lawn signs is treated like any other instance of petty theft, however, signs on the righ...
An object in orbit around a massive body is in a constant state of free fall, so why isn't it accelerating towards an infinite velocity?	For objects in a circular orbit, the force of gravity is always perpendicular to the direction of motion. That means that gravity does not pull the object to go faster in its current direction, but instead only changes the direction without affecting the speed of the object.	[ "In typical free-fall, the acceleration of gravity acts along the direction of an object's velocity, linearly increasing its speed as it falls toward the Earth, or slowing it down if it is moving away from the Earth. In the case of an orbiting spacecraft, which has a velocity vector largely \"perpendicular\" to the...
How does the electric field behave as a charged particle falls into a black hole?	> It seems to imply that to a distant observer, the field due to a charge at the event horizon of a black hole would have to be spherically symmetric around the center of the black hole (at least, assuming a spherical black hole). Ok, when people say a black hole is only described by its mass, charge and angular mo...	[ "A charged black hole is a black hole that possesses electric charge. Since the electromagnetic repulsion in compressing an electrically charged mass is dramatically greater than the gravitational attraction (by about 40 orders of magnitude), it is not expected that black holes with a significant electric charge wi...
Is it colder just before dawn or somewhere in the middle between dawn and dusk?	Assuming no strong cold or warm air advection is taking place, it's normally the coldest just before sunrise. You can clearly see the diurnal temperature trends in [this hourly weather graph for Phoenix, Arizona](_URL_0_).	[ "Daytime becomes longer as the summer solstice approaches, while nighttime gets longer as the winter solstice approaches. This can have a potential impact on the times and durations of dawn and dusk. This effect is more pronounced closer to the poles, where the Sun rises at the vernal equinox and sets at the autumn...
what is java?	I suppose you're here talking about computers and not the dance. ELI5 answer : Java is a programming language which allows to create programs. Long answer : Unlike other programming languages like C++, the code is interpreted by another program (called the JVM, Java Virtual Machine) which renders the result....	[ "Java is a general-purpose, concurrent, class-based, object-oriented programming language that is designed to minimize implementation dependencies. It relies on a Java virtual machine to be secure and highly portable. It is bundled with an extensive library designed to provide a full abstraction of the underlying p...
Why are so many followers of Islam/people in Islamic nations named after the prophet Muhammad?	Interesting, I always thought about it from the other point of view. If you consider a man to be the best human and a role model to pattern your life on, wouldn't it follow that it should be a very common name? Muslims are supposed to love the prophet Muhammad more than their parents and we know that naming children af...	[ "There were Jews, such as Natan'el, who accepted this model of religious pluralism, leading them to view Muhammad as a legitimate prophet, albeit not Jewish, sent to preach to the Arabs, just as the Hebrew prophets had been sent to deliver their messages to Israel.\n", "According to the sixth edition of \"The Col...
How accurate are orbital calculations?	Here's a taste of how accurate orbital calculations are: in 1676 Romer proposed that there was a finite speed of light when he noticed that Io, a moon of Jupiter, was some times 8 minutes ahead of "schedule" (predicted location) and sometimes 8 minutes behind. 8 minutes. 350 years ago.	[ "One of the major problems in trajectory and orbital estimation is to obtain a realistic estimate of the accuracy of the trajectory and other important parameters. In the orbital case, some of the parameters which may not be solved for are geopotential constants, survey, etc. These factors will affect the total unc...
Do ALL plants release pollen into the air?	Plants only produce pollen from their flowers (or cones, etc.). So if your friend would like some plants inside her house she just needs to make sure they don't flower (i.e. cut the flower buds off). Some plants flower more often or easily than others. Cacti rarely flower, in my experience. Ferns produce no flowers bu...	[ "\"Filipendula rubra\" is known for its air-borne pollen, however pollination is only effective (can create a seed) when pollen is transferred to a different plant, due to the fact that \"F. rubra\" is self-incompatible. The vast majority of pollen will be derived from inflorescences within the same clone and thus ...

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