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Why do different races of people seem to have a unique smell to them? | Not sure if its just me, but I always found that I can differentiate races just by their aroma. Sure everybody has their own individual smell (which I'd imagine is a result of varying hygiene practices, laundry detergents, diets, etc), but it seems like theres something else that naturally stands out between races. For example, I've heard some black people describe white people as having a "wet dog" smell to them. What exactly are we smelling? | Most East asians (Korean, Japanese, Chinese) don't have as many aprocrine sweat glands so you'll rarely smell B.O. from them. Also, they don't need deodorant, so if you're visiting, Korea, Japan or China, bring enough deodorant, because you might have a hard time finding some. No-one wants to be the smelly foreigner!
Source: Dated Koreans. [Also.](_URL_0_) |
how Insurance work? | I never have fully grasped everything about it. | Insurance for what?
Basically you pay some fee regularly to the insurance people, and in return they'll cover any costs you might incur related to whatever you insured. If you insure your house and a tornado rips it apart you get paid. If it doesn't you get nothing. If you're a professional pianist you might insure your hands for something so that if you get your hands smashed in a hydraulic press in some accident and can't play anymore you'll have a good payout to keep you afloat.
The insurance provider is betting that the fees they take in from those they insure will outweigh their costs in payouts and they're usually right. |
How can the feeling of nausea be a negative feeling even though it isn't similar to normal physical pain? | Nausea is a basic "negative feeling", just like intense heat and paper cuts produce fundamentally different "negative feelings" (heat and nerve severing, respectively).
Nausea is to food poisoning as painful heat is to fire. Nausea is rooted in the inner ear, which monitor's the body's balance. When the inner ear and other parts of the body that can sense orientation (eg eyes) don't agree, the brain assumes that the body is under attack from an ingested toxin, and induces vomiting to expel the toxin. |
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Why is paying bail an option for criminals who have been arrested? | Isn't it exactly the same as bribing authorities; they're both paying money to prevent incarceration. | They're not convicted yet so you can't really call them criminals. Bail is a way to make sure someone shows up in court later on. So it's based on the idea that if you put down an extravagant sum of money (to be given back to you if you show in court) you are less likely to run. So if you don't seem to be a danger to others, they don't have to hold you in a cell to be sure you'll be in court. I think you also might have to surrender your passport temporarily (and at least are legally forbidden to leave the country or a smaller area).
Not defending that system though. It's almost a godsend for very rich people willing to run away (what's a few millions when you have plenty more to go hide halfway around the world?). |
why aren't oil dipsticks white | All oil dipsticks I've ever seen are black plastic or dark metal. Why not make an white to contrast against the black oil? | Because it's in the engine compartment, it's going to get covered in oil and grime. So they are either black or orange or yellow. Also you read them on the stick, not the cap, and the stick is metal because it goes into the engine and gets very hot. A plastic colored stick wouldn't stand up to the conditions. |
How do psychology researchers obtain informed consent without tipping their subjects off on the subject of the study? | I know that subjects of research studies must give informed consent before they are allowed to participate. I also know that informing subjects of psychological experiments of the study's true purpose can influence the results. How are these two concerns reconciled? | You have to tell them what will happen to them during the study. You don't have to tell them why you are doing it or what conclusions you will draw, except in the vaguest of terms. "You will answer a series of timed questionnaires while being observed by our researchers, to increase our knowledge about how people make decisions". Maybe they don't care about your answers to the quizzes, only your facial expressions while you take them. |
How do laptops tell what percentage of a battery is remaining and when a laptop (or any device) is going to run out of juice? | voltage decreases as power in the battery decreases |
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Why is it that when I am copying multiple folders in Windows and I do it all at the same time, it takes hours; but when I copy the folders one by one it only takes few minutes per folder | On Windows, files are not really arranged on the hard drive in the order that they are on the screen. They are often in completely different parts of the hard drive, a magnetic metal disk in the computer. The computer can only read one place on the hard drive at a time, and only at a certain speed. Thus, if you have two folders next to each other on the screen, they might be in different parts of the hard drive, meaning that they must be found separately. This is further complicated by the fact that large files and folders are often "fragmented", or split into pieces on the hard drive. This means that the computer must skip around the hard drive to find everything, causing it to take longer to read. Fragmentation also applies to writing to the hard drive, meaning that the computer must skip around. Larger amounts being copied at once = more fragmentation = more time compared to going one-by-one. |
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How do genes work to give someone an intellectual advantage over another? | [deleted] | "Intelligence" as a single property is kind of a misnomer - I could be quick to pick up on new information and use it to my advantage, while someone else could have horrible observational skills but a knack for finding patterns in historical data, etc. It all depends on what kind of intelligence you're looking for.
With regard to genetics, all these traits could possibly manifest due to changes between people's brains. Maybe I have slightly better eyesight, or better recognition of body language, or better short-term memory - all due (in part) to the fact that my brain developed with different building blocks than the person next to me.
In short, you're asking how the building materials of a house make it the "best", and two things need to be considered:
1. That "best" is imprecise, and based on how you define it makes different initial conditions ideal.
2. That though the building materials are very important in influencing certain properties, this doesn't happen in a vacuum and there's tons of outside factors that can affect the house's performance. |
New NBA schedule compared to the old schedule | Well, its a pretty vague question, but I'll do my best.
The main purpose of the changes to the NBA schedule is to provide more days off during the season and reduce the number of times a team would play back to backs (ie, a game Tuesday and then playing again on Wednesday) and 4 games in 5 nights (2 back to back separated by a single day off).
The reason for reducing these has a couple of origins:
1. Teams play worse with less rest
2. In recent years, coaches (especially Popovich) have been having players sit out portions of back to back games, to keep them more rested and reduce the risk of injury.
The second issue was the real contreversy, as Popovich on several occasions sat out his stars during nationally televised games or highly anticipated match-ups.
So starting this season, the NBA changed their schedule to reduce these issues. They started the NBA season about 2 weeks earlier than in previous years, but are still going to end the season at the same time. This gives them many more days of rest to put into the schedule. It also gave them more flexibility in scheduling. They have significantly reduced the number of Back-to-Backs the average teams plays this year. They have also made sure that teams playing in nationally televised games (ie, TNT/ABC/ESPN) didn't have a game the night before hand. |
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how world seeds in minecraft and other games that use them work. | Computers cannot produce truly random numbers on their own. For this they would need an external entropy source such as atmospheric noise picked up by a radio receiver; that's how the site [_URL_0_](http://www._URL_0_/) can generate a truly random number. Those kind of devices are required if you run an online casino for instance but for your everyday needs, our computers rely on Pseudo Random Number Generators.
View those PRNG has mathematical rules for which you give and input/seed (a number) it gives you a really, really big number where each digits appear to be random really are tied to the seed.
In Minecraft's, somewhere in the terrain building code, a PRNG is needed to give the illusion that the terrain randomly generated. When you specify a seed, what you are really doing is deciding what to feed to the mathematical formula that will generate the really big number that will be used to build the terrain. Like any mathematical formulas, two exact same inputs will always give you the same output, in this case, the same map. |
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Why do certain tastes last longer on our tongues than other tastes? | The two main factors of taste (gustation) at play are going to be: *initial concentration of agent* and *chemical properties of agent*.
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Let's say we have a high-concentration agent (100x) and a low-concentration agent (10x). When tasting something that has a high concentration of an agent , it means that for every single **equivalent volume** drop of the agent, there will be a higher number of molecules of agent in the higher-concentration agent drop than the lower-concentration agent drop. When we drip a single drop onto our tongues, the agent will immediately begin to be diluted by our saliva. Let's assume that dilution follows the rule: *every 10-seconds, half the concentration of the previous 10-second's concentration*.
So, at 0 seconds of touching your tongue, the respective concentrations of the high-concentration agent and low-concentration agent will be: 100x and 10x. At 10 second, they will be 50x and 5x. At 20 seconds, they will be 25x and 2.5x. At 30 seconds, 12.5x, and 1.25x. So on.
Let's assume our tongue's taste threshold for this agent is 1x (i.e. we cannot sense the taste of this agent below 1x concentration). Notice that by going by our dilution rule, the high-concentration agent will be tasted until 60-70 seconds (where it hits threshold) and the low-concentration agent will be tasted until 30-40 seconds. Notice that there is a 30-second time period where the high-concentration agent will still be tasted after the low-concentration taste goes away!
This is why when you taste something very unpleasantly strong, your salivary glands will kick into a much higher gear (to try and dilute the taste faster).
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Some chemicals will be more "sticky" to our mouth - that is, they prefer to stick to the flesh inside our mouth. Some chemicals will not dissolve very easily in our saliva, so our efforts to dilute it are slowed down drastically. These (and other properties) all affect how long the agent sticks on our tongue and taste-receptors.
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I noticed that you may have been inquiring into why a certain (sweet) taste will last longer than a separate (perhaps bitter) taste. This may be due to the fact that each taste will have different thresholds for chemical reception - i.e. bitter tastes will have a much lower threshold of sense vs. sweet tastes. Thus, bitter tastes naturally stay longer on our tongues. |
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How Does Foam Hand Soap Work? | For years I have always pondered the question, "how exactly does the soap inside that complex container come out as a foam?" I was always scared to find out if I truly wanted to know one of life's darkest secrets, but today I finally muster up the courage to seek this information that has been hidden from us for so long. | If you look at the pump, it has a small chamber, and when you pump the soap, along with some air, is forced through small holes in that chamber, then up and out of the nozzle. The soap itself is also pretty thin and watery; if you took normal hand soap and put that in a foaming soap's container it wouldn't foam up. |
Why do hockey players say the same generic stuff during interviews? | There could be fistfights in the locker room if someone said to the camera interviewer at the end of the game "Bosco wasn't covering his end of the ice on his shifts. A pisspoor effort all the way around; I hope they trade the bastard before he drops our team to the basement." So teams and players try to avoid speaking that frankly when the cameras are on, so they can save their fights for when they're out on the ice. |
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How do helicopters with no tail helix work? | I understand that the tail helix is there to balance the main rotor's torque, but I couldn't understand wikipedia's explanation for helicopters with no tail helix, such as [this one].(_URL_0_). Thanks! | From Wikipedia,
> **NOTAR** is the name of a helicopter anti-torque system which replaces the use of a tail rotor. Developed by McDonnell Douglas Helicopter Systems (through their acquisition of Hughes Helicopters), the name is an acronym derived from the phrase no tail rotor. The system uses a fan inside the tailboom to build a high volume of low-pressure air, which exits through two slots and creates a boundary layer flow of air along the tailboom utilizing the Coandă effect. The boundary layer changes the direction of airflow around the tailboom, creating thrust opposite the motion imparted to the fuselage by the torque effect of the main rotor. Directional yaw control is gained through a vented, rotating drum at the end of the tailboom, called the direct jet thruster. Advocates of NOTAR believe the system offers quieter and safer operation.
ELI5: Basically the low-pressure from the jet nozzle creates a sort of 'vacuum' effect which 'sucks' the tail rotor in the direction opposite the torque. That's it.
By the way, this effect is called the **Coandă effect**. you can demonstrate it by blowing air over a piece of paper. |
Why do super markets like Wal-Mart use see through refrigerators while we the consumers don't? | like, it would solve the whole guessing what's on my fridge and no more will you have to open the fridge every minute.
discuss, please. | Are you trying to sell the food in your fridge? It's a lot less efficient energy and space-wise if you use a glass front for your fridge, so there's really no point unless you're trying to turn a profit in your kitchen. |
What's going on when my browser takes a long time to load, but loads instantly after hitting refresh? | It has [cached](_URL_0_) the content the first time, and when you refresh it is retrieved from the cache. |
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Why does every single call center rep ask for my phone number even though I just punched it into the automated system? | I mean the idea is for them to have my phone number and save everybody time, right? | Nope. entering the number in the automated system is for the automated system only. or if they have regional call centers that take calls from only certain regions it recognizes the number and routes to the correct call center...sometimes...in theory
and also the few call centers that have the intergrated tool. that actually recognizes the data entered in the IVR, The reps have to verify they have received the correct customers info. and sometimes we come back from our hr lunch and the tool is minimized.. and when a call comes in, it pops up to the login screen since its been idle for longer that 30 minutes. so we have to log in and start from scratch. |
How was NYC able to build and afford their entire subway system over the past 100+ years, but the 2nd Ave line keeps running into budget issues and delays? | I've tried to do research on the subject, but I can't figure out the financing and the timing of it all. There have been hundreds of miles of tracks and tunnels and hundreds of stations built over the past 100+ years, but the Second Ave. line has been moving at a snail's pace. Why? | I would say the construction costs have soared. Wages are high for construction workers compared to the past. An immigrant was willing to work for low wages. Now there are unions, OSHA, overtime rules, etc. |
Why do tendons take so long to regrow even though they are non complex and completely internal so no need to get rid of bacteria? | Usually the healing process involves blood flowing to the affected area, bringing with it platelets which release growth factors under certain conditions.
Tendons do not have a rich vascular supply, and to add to the issue - they're made up of thick strands of collagen which have to get repaired. It takes a few days for blood to reach the area. The blood brings inflammatory cells which stimulate proliferation of tenocytes (tendon cells) to produce collagen. Since you need a lot of collagen, by the time it produces enough, it would have already been weeks.
The more collagen produced, the less cells are present so healing gets slower and eventually fibrous tissue is formed.
The entire process takes months and even up to a year. |
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How do stores like Best Buy make money when they sell products like computers or phones without charging extra? | For example, I can order a MacBook for $1499 from apple, or from bestbuy for the same price. How does bestbuy make any money? | They get a small wholesale discount from Apple. Also, if you buy the computer from them, they have the opportunity to sell you all kinds of things - extended warranties, CD-Rs, headphones, cables, software... |
If ocean was forever stagnant, would the salt drop to the bottom? | I would assume that the ocean would be a giant pool for infectious diseases if this would happen. | No because most of the salts dissolved in the ocean are very water soluble. Their concentration in the ocean is well below the saturation point and so the salts have no reason to fall out of solution regardless of the amount of current. |
Why do I squirt saliva when I yawn? | why oh why | It's called gleeking, and it's because the saliva glands in your mouth get pulled and squeezed. |
How can a computer provide a truly random number/response if it's made up of coded instructions from a programmer? | How can structured coding result in a random output? Even for simple simulations such as flipping a coin, how can it fully replicate the randomness of such an event, instead of returning output responding to exactly the probability of each outcome? | It can't. "Random" numbers from a computer are more accurately called "pseudorandom." They usually are generated by a series of mathematical operations on some seed, such as the precise time tick when the function is called.
_URL_0_ |
Why so many people in the U.K. hated Margaret Thatcher. | [removed] | Because her, and her government's, approach to the economy and employment was that people should work hard and pay taxes and anyone who wasn't able to support themselves shouldn't get handouts from the state for loafing about doing nothing. So for me, a young a naive 20\-something who had just started work in 1983 it was great because she kept cutting taxes at all levels but particularly to the top earners, but what I saw was my wages rising. She was a proponent of 'trickle down economics' like Ronald Reagan, i.e. if the rich at the top get richer the money will flow down to what our current bunch of bandits \(aka the Conservative government\) call 'hardworking families'. What was actually happening that lower taxation meant cuts to any kind of state support for the unemployed, the sick, the disabled etc etc. Unemployment was rising rapidly due to globalisation meaning that heavy industries like coal, steel, shipbuilding, car manufacturing etc were collapsing under pressure from competition from the Far East and the US. As someone else said, she hated the miners because they dared to stand up to her, so there are now parts of the UK where there have been hardly any jobs for a couple of generations because she closed pits and steelworks and gave no support in the aftermath \- a bit like places like Detroit maybe?
As I got wiser through the later 1980s I, and many others began to realise that they had no understanding of what it was to be poor and working class, despite her having been a shop\-keepers daughter made good, and that they just didn't care as long as they made money. Sadly we're back there again with our current shower... er...government.
If you want to catch a flavour of it watch The Full Monty \(Sheffield Steel workers\). Pride \(Welsh coal mines and the miners strike\) Billy Elliot \(Miner's Strike in the North East\) |
Why sometimes you flick a light switch and it takes a few seconds to turn on, but as soon as you turn the light off it is immediately turned off. | [deleted] | Some lights have to build up a small initial charge that is greater than the operating charge of the light.
Turning off a light requires no power because it is the absences of power that turns the light off. |
How do Web Browsers work? | . | When you request _URL_0_, the server sends back a bunch of textual data. Plain text is boring to look at, so a simple markup language was created named html. The browsers job is to parse through the html and display it nicely. Some browsers display things differently than others (that's why many people hate internet explorer).
Requesting for a page can be very resource intensive on the browser (intensive in a very relative term). Most sites share similar layouts, so each request may be 95% of the same data (things like the header, footer). It doesn't make sense to request almost the same thing, so caching was invented. A browser stores commonly requested things locally on your computer. Caching improves the time for pages to load, since most of it is stored locally.
Offline browsing uses the cache to save complete pages. If all the content is saved onto your computer, then you don't need a connection to view it. Thus, offline viewing. Offline viewing is only practical for pages which have content that never changes. If the page depends on any user submission, then obviously it won't work.
A session is an exchange of information between the browser and the web application. They use 'cookies' to keep this information sorted. Cookies are nothing more than simple text files that your browser manages. Sessions and cookies are used alot in the internet, but for the average five year old, they keep you logged in for a specific time on a site. Cookies are the reason why you stay logged into Facebook on your computer. The cookie is stored only on your computer.
As for security, browsers don't do much. They can recognise certificates a site must have in order to be 'secure' (Called an SSL certificate). They can also recognize an invalid one too. They aren't smart enough to do much else though, that is left up to the user.
I hope this helps! |
Do relatives have similar fingerprint patters, as is the case with DNA? And if not, why? | I have never heard an example of forensics or science using a fingerprint to connect relatives or eliminate suspects like they do with DNA, at least on CSI. It seems like siblings would have several consistencies between finger & hand prints, and the parents would also have matches as they passed on the traits that created the handprint. If this isn't the case, how come? And if it is, and it is common knowledge, sorry, I'm pretty high. | _URL_1_
"Our fingerprints are totally unique, not even identical twins share the same fingerprints! How they form is very interesting and you are spot on, fingerprints develop in the embryo before a baby is born. A person's fingerprints are formed when they are a tiny developing baby in their mother's womb. Pressure on the fingers from the baby touching, and their surroundings create what are called "friction ridges", the faint lines you see on your fingers and toes."
BTW Someone asked the same question, so it might be useful to read through that (or google?)
_URL_0_ |
Is smoked salmon cooked or raw? And does putting fish in an acid (i.e tuna in lime) cook the fish, or is it still raw despite the change in appearance? | I am always confused by this. People smoked salmon doesn't look cooked, yet some people say it is, and tuna changes colour after being in lime so it looks cooked and it's confusing. | > **Is smoked salmon cooked or raw?**
According to [Wikipedia](_URL_0_):
> Cold smoking does not cook the flesh, coagulate the proteins, inactivate food spoilage enzymes, or eliminate the food pathogens, and hence refrigerated storage is necessary until consumption.
However, it then goes on to say:
> traditionally, in the US, cold-smoked fish, other than salmon, is considered "raw" and thus unsafe to consume without cooking
Personally, I would consider smoked salmon to be uncooked. I think the distinction Wikipedia is making between salmon and other smoked fish is that salmon is the only one which is generally considered safe to eat in the US without cooking.
I'd guess that the reason for this is because salmon is so often prepared this way that the fishing and storage methods involve keeping the fish fresh enough to eat safely without cooking - I'm sure that other fish would be just as safe if it was stored in the same way as salmon.
> **And does putting fish in an acid (i.e tuna in lime) cook the fish, or is it still raw despite the change in appearance?**
Again, using [Wikipedia](_URL_1_) as a source:
> Ceviche is marinated in a citrus-based mixture, with lemons and limes being the most commonly used. In addition to adding flavor, the citric acid causes the proteins in the seafood to become denatured, appearing to be cooked. (However, acid marinades will not kill bacteria or parasitic worms, unlike the heat of cooking.)
So this method of preparing fish is not considered to be cooking. However, the confusion perhaps stems from the fact that the word "ceviche", which describes preparing fish in this way, might derive from the Spanish-Arabic word assukkabáǧ, which itself derives from the Arabic word sakbāj (سكباج) meaning meat cooked in vinegar. The fact that this is the origin of the word is not definite, though. |
why does education generally make people more tolerant and less violent? | Because people fear the unknown. So knowing more also makes your more understanding to others position. It's harder to see issues as black and white when you understand there are nuances to the situation. |
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Why are musical notes the pitches that they are? Why not smaller or bigger increments in frequencies? And who decided this? | Just started learning piano and my curious mind can't stop thinking about it:
For example, why not 16 notes in a standard scale,with the difference in pitch cut in half, instead of 8?
Why does a standard major scale go in steps of whole-whole-half-whole whole-whole-half? And why does this sound normal as opposed to 8 notes of all whole steps? | Let's start with what sound is. Sound waves are compression waves, which means that energy gets transferred from one chunk of matter (air, for our ears) to the neighboring matter in the form of pushing the particles slightly closer together (*compressing* them). If you do this process at certain frequencies, you get sounds of different pitches. That's all speakers do - move a piece of paper back and forth (very quickly) at different speeds to get different pitches. It simply transfers mechanical energy from the speaker cone to the air touching it.
Now on to the musical scale. As /u/lucaxx85 said, it appears to come from nature (it's a discovery, rather than an invention). A pure tone is said to have a "fundamental frequency" (its pitch is defined by that frequency). If you double that frequency, you're one octave above the fundamental frequency's pitch. If you triple it, you're a fifth above that. And so, if you go on and keep multiplying the original frequencies by integers, you fill in the scale most commonly used in Western music.
However, there are musical scales that do not use the standard solfege scale. On that basis, I argue that the whole-whole-half-etc scale sounds normal simply because it's what we're used to. After 10 years of choir growing up/through university, we sang an Indian raga that used 7 evenly spaced tones to form an octave (the octave was still mathematically the same), and had to spend a couple weeks only singing the scales to get acclimated to singing these "new" intervals. But then we were used to them.
I would guess the sound/feeling of resonance/dissonance has to do with how our auditory system works. A quick glance over [wikipedia](_URL_0_) confirms this, but adds that it's culturally conditioned. That is, all people can hear consonance/dissonance, but which intervals are consonant vs dissonant is determined by the musical tradition.
Source: physics bachelor's, many years in choir, and an in-progress master's in systems-level neuroscience
**TL;DR** Octaves/other intervals are mathematically defined, but how normal an interval, chord, or progression sounds is culturally determined |
What are the little black dots you see when you close your eyes lids with light in the background? | They move around too which makes no sense to me. | Those are called [phosphenes.](_URL_0_) They're caused by the cells in your eyes being stimulated as if you were looking at something, even when they're not looking at anything. |
Why do reddit servers go down so often compared to other major websites? | [deleted] | First, compared to something like Amazon, Reddit going down for an hour costs very little revenue. Linked to this, if Amazon or Google goes down, you'd go to another retailer, or Bing. If Reddit goes down, what you going to do about it?
Second, speed and load. Reddit really doesn't need speed. You load a page, read some comments. A second load time isn't huge, and text loads fast anyway. For a search engine, it's huge, particularly with predictive searches. What this means is that a site like Google is optimised for speed. Part of this is data centres around the world. An upshot of this distributed model is that it makes redundancy really easy as a side effect. Netflix has a huge load, and so needs a distributed model - which helps uptime. |
Why is February the month with 28 days, and not April, November or any other one? | There was a time when the year began in the month containing the beginning of Spring, namely March. This meant that February was the last month of the year, and it originally had 30 days.
July and August were renamed for Caesars of Rome and at the time those months were only 30 days. To honor the greatness of the Caesars, those months were extended to 31 days each and the days were taken from the end of the year, which at the time was February. |
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How did we come to use $ as a symbol for Dollars? | There is a column in the [Straight Dope](_URL_0_) that discusses several of the theories already discussed, and concludes it came from the peso abbreviation 'ps' being written over each other. Relevant quote below:
> So much for the tomfoolery; now to get serious. Professor Cajori contends that the dollar sign is an abbreviation for "pesos." Bear in mind that the Spanish dollar, also known as the peso de 8 reales, was the principal coin in circulation in the U.S. up until 1794, when we began minting our own dollars. In handwriting, "pesos" was usually abbreviated lowercase "ps," with S above and to the right of the P and with the hook on the latter written with one or two deep strokes. As time went on, the P and the S tended to get mashed together and the result was $.
> The dollar sign and the PS abbreviation were used interchangeably from around 1775 until the end of the century, after which the latter faded from view. Professor Cajori backs up his argument with examples from manuscript, and I'm prepared to declare the matter settled. |
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If a car is rear ended, the force should push the driver backwards? which laws of motion apply? | the collision force should throw the driver backwards? i.e. why whiplash is common. how do would this be explained with laws of motion? | The driver driver is not pushed backwards, the driver remains where he is while the car is jolted forward. This makes it *appear* like the driver goes back relative to the car. |
Why and how does lightning vary in color? | There have been several thunder storms where I live, and I've noticed that the color of lightning varies every time. From almost white, through purple/blue, even to yellowish tones. Why does this happen? | Depends on the voltage and current released in the lightning strike. The light comes from ionization of the air and excited electrons in the plasma. Depending on the energy the electrons absorbe, differrnt wavelengths (colors) of light will stand out. For instance, blue lightning is more energetic than yellowish/red. |
if we know more about space than we do our oceans, why don't we spend more time exploring what we already have here? | We can use a telescope to look into space. A lot of what we know about space is by confirmation of equations. Scientists believe that x should be y because of z. They take some measurements over a few years and then publish the results.
Looking into the ocean has limits. We can only look so deep. We can only scan so much. Take a globe. Take something smaller than a pin head for scale, and start drawing lines in the ocean, that's how it is scanned. Our satellites now have some capability to look at the oceans, but their penetration is also limited. They can do visual and heat.
I suspect that once we build powerful enough satellites we may be able to set them in orbit in some kind of array that could scan and penetrate all the way to the ocean floor.
Also, what do you hope for us to learn form the ocean? We pretty much figured it out a few thousand years ago, all we are doing now is adding achievements to it.
And lastly, space is all we have left. While gaining a better understanding of the oceans is a noble pursuit, it's really only beneficial to those who deal with it. By that I mean there's a whole planet of people here, many of them live inland and some don't know what the ocean is. Someday we may need to leave this planet and pushing space exploration will enable humanity to spread amongst the stars while studying the ocean is really only applicable to earth. At least that's the general idea IMO. |
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Why must it be the U.S. to "degrade and destroy" the Islamic State? Why can't the surrounding countries do it? | Surely there is enough military might in the surrounding Middle Eastern countries to deal with Islamic State and prevent their advance? Surely these countries have a vested interest in doing so? | Foreign Policy ELI5:
It's a warm Summer's eve and you are sitting comfortably in the park eating a delicious ice cream. As a drop of melted vanilla fudge rolls down your fingers, your eye catches the glimmer of a struggle in the sandbox. You turn to witness a bully beating up the other kids and stealing their ice cream.
You are horrified. There's an entire field and jungle gym that separates you from this bully, yet still you fear that your ice cream will face the same fate as the poor wee children now laying in a silent, ever-so-slightly-twitching heap.
While it is completely possible that the children still left standing in the sand box will be able to over power the bully, you **really** want your ice cream. You want it so much, that you don't even want to risk the possibility that it may be taken from you. So you tilt the odds in your favor by escalating your response:
You tell your Mommy.
Over kill? Maybe. Could things have worked out without telling on the bully? Sure. But, at the end of the day, you involved the full force and authority of a grown-up to ensure that your interests were more likely to happen than their alternatives: no ice cream. |
Why is Jimi Hendrix largely considered the greatest guitarist ever? | Jimi was ambidextrous with the guitar playing it either way. Predominately playing a right handed guitar left handed. He could also play with his toes, teeth and behind his back. He was a pioneer into the effects of the electric guitar bringing distortion and wash wah pedals into mainstream. Aside from all of that he was a complete virtuoso that is widely critically acclaimed as the all time greatest. |
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How do ticket scalpers buy all the tickets to a show only seconds after they go on sale? | Every one of Brand New's tour dates sold out under a minute and hundreds of tickets immediately show up on stub hub for twice as much. So many fans are complaining that they couldn't get tickets even though they were refreshing the page the second they went on sale.
How is it that possible? | Because most of them never go on sale to the public.
_URL_0_
This is also a good read:
_URL_1_ |
If the universe is infinite and expanding, what it is expanding inside of? Something more infinite? | I mean the universe is supposed to be infinite right? So how can it expand first, and then what it is expanding into? Something "infiniter"? | Suppose there's an infinitely large piece of paper. You've drawn something on it. Every day, you add a little to the drawing, making it bigger or more detailed (or both).
As time progresses, you start using more and more paper. Is the currently unused paper part of the drawing? No. That's just empty space. It contains nothing related to a drawing, because it needs to be a blank paper *so you can then draw on it*.
Can we see the blank paper? No. Why not? We are part of the drawing.
**Second idea, as suggested by a friend**
Suppose you're looking at a picture on your 21" monitor. But people tell you you're not looking at the whole picture. So you click the 'zoom out' button, and get to see the bigger picture (figuratively).
Did your 21" monitor become bigger? No. But the content of the monitor became more detailed. Maybe the universe isn't expanding, but only becoming more detailed, within the same boundaries. For someone observing from within (like us), we would assume the universe gets bigger because more stuff (details) is added. |
How would the EU effectively retaliate against anything, should they be against what the United States has implemented? If things took a turn for the worse on the Paris Agreement, what would a hard stance against the US look like? | The most effective tool the EU would have would be sanctions against US companies that they decided were not meeting environmental standards.
They could drastically raise tariffs on those companies, or forbid them from doing business in the EU altogether.
More generally, they could back out of trade agreements with the U.S. which could have the dual effect of making popular European items rare and expensive (think German cars, Swiss chocolate, etc) and making it very hard for US companies to sell goods in the EU.
This is pretty unlikely though - at least for right now. The US-EU trade volume benefits both sides, and the hit to the EU would be as severe as the one to the US; both economies would suffer, although arguably the EU would recover first.
A more likely approach is just that they might be less inclined to participate with us on a variety of things from diplomatic issues to military interventions to intelligence sharing. Sort of a "if you don't want to play with us, we don't want to play with you" situation.
In any case, it's likely to only last as long as the Trump administration. The US will reverse course on this as soon as we get someone in the WH who isn't so stupid as to believe this is all a hoax that EVERYONE except him is falling for... |
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Even if a self-declared socialist politician such as Bernie Sanders won the presidency of the United States how much could he really do and change with a conservative Congress? How effective would be his political powers and freedom to realize his goals in such a scenario? | Presidents vary in their ability to manipulate Congress.
Some are terrible at it, like Obama and Carter. Some are average like Reagan, Clinton and Bush. A few are masters like LBJ.
The difference is understanding on a specific, person-by-person basis what it takes to get votes, and the willingness to do whatever is necessary to make that happen (even to the extent of making corrupt deals from time to time).
All Presidents need leverage over Congress. Those who succeed figure out what that leverage is and how and when to use it. Those who don't end up complaining bitterly and endlessly about dysfunction and gridlock. |
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Everyone in the world raises their arms/fists to represent success and victory. Why is that? | Every culture (to my knowledge), every country, and every civilization that all developed independently of eachother, and yet everyone raises their fists or arms up in the air to proclaim 'yes!' or 'victory!'.
Why is that? | It is just a human reaction. Recently, saw a video on TEd talks about body language. It said there was a study done and when someone who was blind and has always been blind won a challenge they raised thier hands up in the air, in victory. Even people who have never seen that done, react that way. |
The Australian equivalent of the American education system. Junior, middle, high school, college, GPA etc. | If someone could please break it down to an Australian style equivalent so I could finally understand. | Aussie here. I'll do my best, but keep in mind that my understanding of the US school system is based on my recall of the Babysitter's Club.
Elementary School more or less equals Primary School.
Middle School and High School are often combined in Australia into a High School or Secondary College, although a number of towns (in Victoria, at least) over the last ten years or so have formed education collectives which result in some former Year 7-12 High Schools shrinking their intake to Grades 7-10, while another school in the area focuses on Grade 11 and 12 only. These tend to be called "Middle Years College"s and "Senior High School/Senior Secondary College"s
My understanding of community colleges places them somewhere alongside TAFEs in the Australian system, and the American College equates to the Australian University. When someone in Australia refers to going to a college when they are of post-high school/university age they are usually referring to a residential college, a place for living on campus, similar to a dorm house.
Australian high schools don't typically use the GPA (Grade Point Average) system, our equivalent is the post HSC/VCE "ATAR", which ranks students for tertiary entry based on their high school results and the popularity of the university course.
While GPA seems less of an issue in Australian unis than in American colleges (especially once you finish uni), they are sometimes used during uni to determine eligibility for certain programs, such as international exchange or honours.
I hope this has helped! |
What is the phenomena known as "Summer Reddit"? | High schoolers are out for the summer, so they're able to be active on the site during the day. Some redditors feel that this leads to a lower quality experience. |
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Why does the price of precious metals not go down as global supply increases when they are discovered, mined and processed into the world economy? | daughter asked, I couldn't answer, ELI5 | supply + demand = price
So while some is found, some is used, more is needed for new innovations etc.
You can't focus on half the equation |
Why is it that when I sleep less, I feel more energized than if I were to sleep a full eight hours? | When I say, "sleep less", I mean around 4 hours of sleep. | I just watched a video about sleep that talked about this.
In each sleep cycle (about 90 minutes) we go from REM to Stage 2, 3, 4, then up to 3, 2, and REM again. We typically experience 4 to 5 cycles like this each night.
Deep sleep (stages 3 & 4) is what our bodies benefit from the most, but we only experience deep sleep during the first couple cycles. Later cycles stay primarily in REM and the lighter stages. This is why we dream so much when we sleep longer, because after 6 hours of sleep we are mainly in REM sleep (often referred to as dream sleep).
An added interesting tidbit: Recent sleep studies have found that increased REM sleep is related to negative thought patterns and even depression. Also, alcohol may allow us to fall asleep quicker, but it also impairs our ability to experience deep sleep. That is why we sleep fitfully, dream more, and feel less well-rested after drinking. |
What is even happening in our brains that we get so happy that we cry? | Crying is sort of a way to dampen emotions. Crying obviously can happen whenever we experience something intense; eg pain, sadness, happiness, etc. Crying is a way to make those emotions less intense/allow us to handle them and avoid overstimulation (which generally is harmful to the body). That's my very rudimentary understanding at least, hope it helps. |
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The science behind a classroom of commotion randomly going silent at the same time. | Really curious about this one. | Mathematically this is bound to happen. No one person is talking constantly but the noise level stays up because voices are constantly overlapping. All that needs to happen for a weird silence to occur would be for all the breaks in conversation to happen simultaneously. We can estimate some values to see how often this would happen in a class of average size. Say 20 students are all having conversions in which they are only actively talking about 30% of the time (groups of about 3 with a little transition time between speakers). And let's also say that it would take about a half second of pure silence to be noticeable. So given any half second interval there is a 0.7^20 or 0.08% chance that no one is talking. So now to figure out how long it would take before there is a 50% chance that an awkward silence has occurred we need to do 0.9992^x=0.5 or log (0.5)/log (0.9992)=x. So x is equal to 866 or 866 half second increments. So after about 7 and a half minutes we would expect about 1 random silence to have occurred.
These are very rough estimates and a computer simulation could give a much more accurate answer. |
How do Ben & Jerry's/Haagen-Dazs etc keep cookie dough/Oreos so soft? | Shouldn't they be rock hard if put in the freezer? They're even softer than regular cookies and Oreo's | the same thing that keeps shelf cookies that aren't made fresh from becoming "stale", that is, brittle and not soft: trans fats.
trans fats are a type of fat you can use in baked goods that doesn't go bad or rancid very fast, in fact it can last for ages and you see hostess pies made with it that are literally stored at room temperature on a shelf for *weeks* before they're sort of nasty. This type of fat stays fatty-textured(not quite solid, not quite liquid) at different temperatures because of the way it's molecule is made up.
You see, wax, oil, and fat are technically all the same type of thing, they're lipids. But anyone can tell you that butter melts into oil on a hot day, wax becomes soft and buttery under a hot flame, and fat turns wax-hard when you put it in the fridge. They all behave similarly, but luckily for us, the *good* fats we use in our bodies are all nice and liquidy at body-temperature.
trans-fats however remain buttery nomatter what you put them in; hard ice cream, hostess pies on a shelf, hell-- you can keep margarine in the freezer section and it's soft as room-temperature butter while the real butter is a brick so hard you can hammer a nail into a wall! That's so convenient!
the thing is, they have a downside. When you eat fat, your body uses it for a ton of different things. Fat is actually a *nutrient*, your body needs it to function properly! It's used everywhere, from the cushioning of your muscles, to the neurons in your brain, even down to the teeny little cellular walls your blood cells communicate through. If you eat a ton of trans fat instead of the good omega fatty acids and/or the monounsaturated fats, it begins to replace in your body what normal fat is used for.
If your cell walls are made of lipids that are nice and permeable, because their molecular structure is made of *good* fats, you have a healthy body. If your cell walls start to be made of *bad* fats that can't remain nice and permeable at body temperature, and are waxy and harder than normal lipid walls... well, you're going to have a bad fucking time. And by bad time, I mean plaque buildup in your veins, impermeable cell walls in your heart, and it becomes harder for communication between said cells, you get high blood pressure, which leads to heart disease and stroke.....
....all because trans fats keep baked goods, breads, and other shit on grocery store shelves consumable for longer, leading to less spoilage and higher profit margins for food companies. A fantastic rule of thumb for eating fresh and healthy foods, is that **the more perishable it is, the better it is for you, probably.** Just make sure you buy shit same-day if you can and/or freeze it.
luckily for us trans fats are being phased out because now the public knows how bad they are for you, you'll see lots of delicious baked goods with no trans fats in them, which means they probably have a little bit of trans fat? But honestly if you're going to eat fatty, sugary-ass foods, go *whole hog* and get the good quality full-butter ones. Eat two of those, and be happy and satisfied, knowing that health comes from moderation in ALL types of foods, even nutrients, but that eating ben and jerry's ice cream with cookie dough in it once in a while is extremely necessary. |
If lightning is hotter than the sun, how do people survive getting hit by lightning? | Only a very small amount of air (or flesh) is heated to that extreme temperature, and only for a fraction of a moment. That heat dissipates pretty quickly since there's so much surrounding material to soak it up.
However, getting hit by lightning can still absolutely kill a person, and usually causes severe burns and scarring. |
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Why does crying affect breathing so much? | When a person's physical or emotional state changes, breathing changes right along with it. And interestingly enough, a change in breathing patterns also affects your emotions. |
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What exactly is shadow banking? | Shadow banking is the collective term for organizations that offer bank like services, but aren't regulated as banks.
Because banks take deposits from the public, they allow multiple people to have a claim on the same money. This is a very important role banks play in the modern economy, and because of this role, the government has a huge number of regulations that are special for banks. However, complying with these regulations is expensive. Traditionally, the margin that deposits provided meant that banks had a pricing advantage against other competitors (these advantages became the source of the term banker's hours).
However, as the costs of compliance rose and liquidity in a few markets improved, the cost advantage of accepting deposits stopped being large enough to keep all competitors out.
Eventually, non-bank firms began to offer bank like products (not deposits which would entail taking on regulation costs) but loans and guarantees. These firms are not regulated by banks but can offer loans as though they were banks.
An example of a shadow bank that anyone can participate in are lendingclub and prosper, which have grown dramatically during the bank crisis when credit became hard to get for many.
Most shadow banks are firms like insurance companies or hedge funds that thanks to credit default swaps (a way to trade just the credit risk of a loan without the rest of the loan) and futures and swaps (ways to trade the interest rate risk of a loan) to become very important providers of credit to the economy (either through banks or by themselves).
TL;DR. Non-bank firms that provide loans (or products that allow others to provide cheap loans). Because they aren't banks, they have much less regulation than a bank would. |
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Why are their expiration dates on medical oxygen tanks. Does the oxygen actually "expire"? | My impression is that the oxygen does *not* actually expire. But are there other factors, such as the integrity of the tank and nozzle, or contamination of the oxygen from the metal casing? Some coworkers were talking about how dumb it is that oxygen tanks expire and it got me wondering about whether there is a good reason.
I suppose this question may apply to industrial tanks, too. | You answered your own question.
The tanks are certified to hold the amount of oxygen they say they are holding without malfunctions for a certain amount of time. In theory, it's possible for an oxygen tank that has been stored and maintained perfectly to last much longer - maybe even forever - but in practice the manufacturer can't guarantee it past a certain amount of time.
If they didn't have expiration dates, you could dig a rusty 60 year old oxygen tank out of some closet and use it, and if it doesn't work properly you can sue the company that made it. |
Why is clothing often times ripped off of the victim's bodies during deadly plane crashes? | We saw it in gruesome pictures from Malaysia flight 17 that crashed in Ukraine. Now I'm seeing the same in images from Air Asia 8501...Why are recovered bodies often times found naked? What happens during the crash that causes clothing to be ripped from the bodies? | "If the clothes are missing, usually that means that [the passenger] was probably either ejected from the plane or exposed to extreme wind blast going hundreds of miles an hour, falling out of the sky,"
"The effect of very high speed wind, or the slipstream, hitting the bodies can easily literally rip the clothing right off."
Ref _URL_0_ |
What happens during spring that causes allergies? | [removed] | What happens in spring? **Pollen!** It's literally plant sperm getting up in your face and setting off our immune system. Your immune system is then over-reacting, treating harmless pollen like a dangerous invader, leading to swelling and other effects. |
Why are toilets and other bathroom fixtures often made of ceramics and porcelain? | Hard surface that is easily cleaned and is non porous. Stainless steel would be the next logical material but is still a bit more expensive. |
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Evolution. | I'm taking AP Biology this year and the books Survival of the Sickest by Dr. Sharon Molem and Your Inner Fish by Neil Shubin was our required reading. Now, I'm more curious to learn more about evolution. Is someone able to explain it to me like I'm five? | Evolution simply means "change over time".
What we see in nature is evolution by natural selection, which is *how* species change over time.
Think about what you know about domesticated animals. Dog breeds, for instance. These have been "artificially selected" to look and act the way the breeder wants. That is, a human decided which individuals will mate, reproduce, and pass on their genes to their offspring, and which will not. When this happens in nature because of the species' environment, we call it natural selection.
Natural selection explains all the variation of all life we've observed so far. There are no contradictions to this theory, and it would only take one true contradiction to make the theory invalid. Evolution by natural selection not only explains all the variety of life we see, but it also predicts things like antibiotic-resistant bacteria and extinction of species due to overfishing.
Evolution is not progressive; it doesn't have a "goal" or ultimate form that it works towards. It is simply the idea that individual organisms that are better suited to their environment will live and reproduce better than less well-suited individuals. The more successful organisms will pass on their genes.
Edit: There are many [online evolution games](_URL_0_) you can play around with. This is just one, google and you'll find more. |
Why is the number "6" is the upside down version of "9" or vice versa? | I realise it is a dumb question but I really want to know. | Coincidence. They evolved from an old writing system used by the Hindus (we call them "Arabic" numerals, but this is inaccurate) over many centuries, and started off looking very different.
Here's how the number 6 evolved: _URL_1_
Here's how the number 9 evolved: _URL_0_ |
What is the difference between grammar and syntax? | Syntax is about how you arrange words into sentences. Grammar includes syntax but also *morphology*, or how words themselves change depending on their role in a sentence. So 'I go to the store yesterday' is a morphological error because *go* doesn't need to move around in the sentence, only change into *went* so that it is in past tense. 'I to the store yesterday' is a syntactical error - it lacks a verb and so doesn't form a complete sentence. Both are grammatical errors, though. |
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Does light reflect off of gravity | Like surely for us to see black holes some light is reflected back? Or am I misunderstanding? | Gravity can bend light, but not reflect it. We don't see black holes quite like you're imagining. We see the way their gravity bends light around the black hole, or we see their gravitational pull on nearby objects. |
Quantised Inertia | "Quantised Inertia" is a theory used by Mike McCulloch to explain the rotation of galaxies (without the use of dark matter) and the apparent propulsion produced by the "EMdrive". But wtf is it? | Mike McCulloch is a crackpot who doesn't really know any physics. His idea of "quantized inertia" is pure nonsense, and it's been debunked many times over.
As you can see from [his website](_URL_0_), he's not a physicist, but rather he's an oceanographer. So he really has no place trying to rewrite fundamental physics.
[Here](_URL_1_) is mathematical physicist John Baez's take on it. |
whats a sinkhole? and how do they get so big to the point they swallow buildings? | I worry WAY too much about anything weather or natural disaster related, (we had a funnel cloud where i live once and i had nightmares for weeks) and today, a sinkhole opened up in my city which absolutely TERRIFIES ME.. Its only small, but of course I worry its gonna get huge and like destroy the whole city.. So I was hoping someone could inform me a little better so hopefully I won't have nightmares for weeks after today lol | The ground you see has layers of different materials. *Some parts of some of these layers can be washed away by water flow if there is any*, or even [corroded by the slight acidity of rain](_URL_1_), leaving natural cavities behind.
Where these cavities are near the surface there can be a collapse creating a sink hole.
If you are worried then reread the portion in *italics* above: Some parts ... some layers ... if any water ... . It just doesn't happen often. You've probably got more chance of winning the lottery than falling down a sink-hole, [just take care when you buy your ticket.](_URL_0_) |
When people talk about "rendering" a video for x amount of time, what is the process that is taking place? | Do they leave the computer turned on until the video renders? What about a video that takes weeks, or even years? | Basically the computer program needs to calculate what exactly will appear on each point of the screen, for each frame. It needs to take into consideration the objects that are in the scene, their location and appearance (colors, textures etc.) and especially the lighting.
> Do they leave the computer turned on until the video renders?
Yes.
> What about a video that takes weeks, or even years?
Each frame of the video can be rendered separately. This allows the rendering process to easily split to multiple computers on a server farm - instead of having one computer work for 5 years, you can have 100 computers work for two and a half weeks. |
How come there is a 50% chance that two people out of 23 randomly selected people share the same birthday? (And 99% for two of 75 people) | [removed] | If I am standing in a room with 22 other people there is a 22/365 chance one of them has the same birthday as me. The next person has already been calculated with me so he has a 21/365 day chance of sharing a birthday. And so on and so on.
But the problem isn't that someone shares a birthday with me specifically it is that any two people share a birthday. The possible combinations of people and therefore birthdays in a group of 23 people is 253 pairs that can be made.
The problem makes a lot more sense when you think beyond yourself and examine the group. |
What exactly does a Business Analyst do? | I've tried searching on google but I keep getting complicated definitions of a Business Analyst. Can anyone please take some time to explain like I'm 5 lol? | Writing as an IT analyst:
*Keep* *asking* *the* *questions* that Kipling wrote about in Six [Honest Serving Men](_URL_0_)
"What and Why and When
And How and Where and Who"
A business user might make an apparently trivial request for an new field in a system, to store another phone number. So I ask:
"What length of number do you need to store? Is it an internal extension number? Is it an international number? Have you considered whether you need to store the country code separately? Why do you want the number? Who's going to read the number? Does it need to restricted to a certain subset of computer users by some set of security rules? Who is going to enter the number manually? Could you get the number more reliably from another existing IT system?
Once it's absolutely clear what the user wants, review this with the developers to see if it's possible, how difficult it will be, how much it will cost.
Because our company uses [Agile](_URL_2_) development, I write it all up as a [User Story](_URL_3_) with a set of [Acceptance Criteria](_URL_1_) e.g.:
User Story:
"As a Sales Representative, I can find my customers Fax Numbers, so that I can send them quotations"
Acceptance Criteria:
Given that I am authorised to use the system as a Sales Representative
When I browse to a customer record
Then I see the customer's Fax Number displayed
(The above is of course an example only, and is shortened summary) |
How do companies that provide “free credit reports” make money? | [removed] | The big one that I know of is credit karma. Lots of people on here have recommended it. Thy say right on their website that they make money through the advertisers that pop up on the page, most of them are financial products that may be of use to you, and if you use one of those services, like a credit card application, then credit karma gets paid for that. They do try to tailor it to products that you could use, or that you’d get approved for. The only downside is is that the score they give you is a vantage score, and not a fico score, so it may be a little different than a bank would see when pulling your credit. But it does give you a ballpark figure. And it only gives your reports from 2 credit bureaus, not the third one. Equifax, and trans union, not experian. |
The difference between disposable contact lenses and the ones you can use for 6months to a year. | Are the disposable lenses made of material that encourages bacteria growth? How come you can't clean them the same way as regular lenses and keep them just as long? Or can you?
Thanks in advance | I unfortunately don't know the answer to this question, but I thought I should respond to the "I wear my '2-week' lenses for months!" vibe here. DON'T DO THAT! F'real. I'm a microbiologist, and while I don't study this stuff myself I've seen some talks and papers about wearing old disposable lenses. Bacteria love being on contact lenses. Think about it: no immune cells on the surface of your eyeball, it's moist and warm between the lens and your eye, a ton of protein for food in your tears. You can try to scrub them off when you take your lenses out for the day, but after a few weeks it becomes really hard to get all of them off because they start laying down glue, basically, to settle in for the long haul. This is called a biofilm, and bugs are really hard to clear from one of these. Then, your lenses are little petri dishes you mash up against your cornea for hours and hours a day. Eventually, some of those bugs are going to hop off the lens and start digging around in your cornea. Some species that are especially nasty at this, like Pseudomonas aeruginosa, can go from "kind of itchy" to "full on pus-bag corneal keratitis" in less than 48 hours. Then it's too late and you need a corneal transplant. The risk of infection goes up drastically after 2 weeks for disposable lenses, even if you don't wear them every day. I know they're expensive and it seems dumb to keep throwing them away, but trust me, do it. Just wear your glasses for a while instead. Ladies love glasses anyway. |
Compound Interest | This seems like the sort of thing I will be facing in the future, (mortages, insurance benefits, et al) and I want to make sure I have a good grasp on it. A basic example and some explination of your math would be a great help. | Let's say that you want to borrow $100 from me. I say that it's fine but each week you don't pay me back, you owe an extra 10%. It seems fair to you and you agree. After the first week, you've made no payments to me so 10% of $100 means you owe me an extra $10. Now you owe me $110. Another week goes by and you still haven't paid me anything. 10% of the $110 (how much you now owe me) is $11 and you now owe me $121.
Now, if we'd made an agreement that you were going to pay me simple interest, you pay $10 of the original amount *only* instead of the new amount that you owe me each week. So after the worst week you'd owe me $110 and the second week you'd owe me $120. The interest payments never change.
This doesn't sound like a huge difference but when you're talking about million dollar loans over 30 years, compound interest makes a really big difference. In fact, Albert Einstein once even said that the most powerful force in the universe was compound interest. The moral of the story is; don't take bigger loans than you need to and ALWAYS pay them off quickly if you can. |
why do Bitcoin atms require a photo id, palm print and government issued id if Bitcoin is supposed to be anonymous? | The draw to Bitcoin is anonymity but these "public atms" want more personal info than the DMV..
TLDR: bitcoin is not anonymous, US law requires collecting info for anti-money laundering reasons. | In the USA, anti money laundering mechanisms are in place for Bitcoin ATMs. This means each transaction must be traceable. There's nothing stopping you though from using other sources to purchase bitcoins using cash.
_URL_0_
On March 18, 2013, for instance, the Financial Crimes Enforcement Network (FinCEN), a body within the US department of treasury that is tasked with ensuring the financial system is not abused by criminals, issued guidance on running of exchanges and ATMs for virtual currencies.
This document officially classified Bitcoin ATMs and exchanges as Money Services Businesses (MSB) or money transmitters. This requires them to adhere to the Bank Secrecy act of 1970.
That means that every Bitcoin ATM running enterprise has to put in place anti-money laundering(AML) mechanisms, keep personally identifying information about its customers-Know Your Customer(KYC), as well as report any suspicious transactions to FinCEN. |
Why can't bones grow back? | They grow when a child is growing to adulthood right? Well why can't they regenerate? Seems like it would be a nifty advantage. | They do? That's why broken bones heal. If you mean why do severed and seperated bones not grow back, that's because of our genome. We don't have the "programming" to grow it back. Bone cells are too specialized to create the proteins necessary to grow back like that. Children's bones grow from their growth plates. The cells there are constantly dividing. By adulthood however, all of these cells die and the bones stop growing. This is why when a child damages their growth plate, they will have growth issues. |
If Mars' atmosphere was lost when its core cooled and lost a magnetic field, why are we trying to terraform Mars to bring back an atmosphere? | Won't this one also be blown away by solar wind? | We're talking geological timescales. Supposing we had the technology to get an Earth-like atmosphere on Mars, maintaining it against the relatively minor loss due to solar wind would be simple compared to that. Mars lost its atmosphere over millions of years, it just wouldn't be a concern for a civilisation advanced enough to terraform Mars to begin with. |
Religion vs Cults | Its contentious, there are a number of different definitions of the term:
Theological = A cult is anything that differs from the religion as conventionally accepted
Sociological= a cult is anything that deliberately opposes mainsteam culture
Psychological = a cult is defined by a set of specific psychological techniques.
So under a christians definition the church of LDS might be a cult because of how it differs from mainstream christianity. While to a sociologist it isnt because its big enough to be recognised in its own right.
When people call Scientology a cult they're drawing on the latter definition. They're referring to the kind of psychological tactics it uses. |
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When watching shows set in earlier centuries, the "Lords" or "Estate owners" always seem to be lounging all day or attending balls. Where was their wealth coming from that they didn't have to work at all? | I'm binge watching The Tudors and can't understand why nobody has a real job, but are still wealthy. | First off, don't trust TV. As far as the income of nobles in those days it came from 2 sources. 1)They owned a lot of land and got the profits of the production of that land. 2) They were the government back then, and taxes were paid to them.
As far as what they did all day generally they held court where they heard from people asking them to do things or resolve disputes or mete justice in criminal matters. They also had to deal with management issues for their properties. They also hunted, a lot.
A lot of medieval aristocrats spent 6 months a year hunting. This wasn't modern hunting, going out on weekends ambushing deer from a blind or stand. They hunted actively in packs chasing down prey and killing them in hand to hand combat. Organizing the groups, getting them in the field, locating animals, tracking them, chasing them and killing them were all a form of military training which was the other main job these people had. |
Why are most knock-offs of products made in China? | Because most regular products are made in China: the resources and facilities are already there, the only difference is quality control and who gets paid. All they have to do is take the LEGO molds, pour their own plastic for it, and make their own boxes, and you get stuff like [these](_URL_2_) ["Brick"](_URL_0_) [products](_URL_1_) |
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Does wearing jade as jewelry actually make it a "greener" green and if so, why? | No, there is no indication that wearing jade will change its color. This is a common myth championed by those trying to associate it with mysticism such as "energy" or "vibrations". |
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How doe home owner associations have any power? | I can't understand how arbitrary rules and regulations help anybody. How do they enforce these "codes", and what happen if somebody says, "I bought this house so fuck off". I got this idea from reading that recent thread on /r/AskReddit | Most people who are under HOA rules got that way when they bought the house and agreed to the rules of the HOA. You sign a contract and so they can enforce that contract. You also agree that if you sell the house you will require the buyer to sign that contract in order to buy the house. |
why do bugs lay on their back when they die? | Just swept up a roach, and had this thought. | When a bug is ailing, either from pesticides or dehydration or starvation, they lost coordination in their legs. Their legs tend to bend or curl. This is either because the legs relax naturally and curl or because blood stops flowing to the legs and as a result, they curl. They also tend to struggle against this and randomly push with their legs, which tends to cause them to tip over. The ailing bug has lost the ability to control its body in the way that is required to get it back on its feet. As a result, most bugs wind up on their backs when they die. |
Why do roses have prickles? | [removed] | As in thorns? They're for protection from predators, plus they help the plant to retain water by catching it as it drops down, and resist wind activity by providing more surface area for the wind to hit, spreading the force out. |
If Ebola is so difficult to transmit (direct contact with bodily fluids), how do trained medical professionals with modern safety equipment contract the disease? | They're in contact with bodily fluids far more often than you or I would be. They take precautions, sure, but when you deal with something that frequently unlikely things can happen.
EDIT - I should have also mentioned something about fatigue and how it can cause individual lapses in safety protocols. This probably contributes pretty heavily, too. |
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Why does burping a sealed container (e.g. Tupperware) help food stay more fresh? | By reducing the amount of air in the container, you reduce the chance of oxidation and bacteria growth, but the main reason is that by lowering the air pressure inside the container, it stays closed - outside air pushing harder on the lid than the air inside.
As long as it is sealed, no new pathogens can contaminate whatever is inside. Keeping it airtight also prevents aromas to mix, spoiling the flavour. |
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are reality-style game shows (survivor, big brother, the challenge) obligated to be "fair" | Explained further... Can producers legally skew a game to benefit certain players? Could they "rig" a competition in the interest of ratings? | They are only regulated by the audience. If an audience found out of a show with any sort of foul play, especially if the show advertised otherwise, then the show would lose views and therefore profitability. So its in the interest of the producer to regulate fair play, but he doesn't have any legal obligation to. |
The security implications Microsoft's "golden key" backdoor, present in all copies of Windows since Windows 8. | Lucky for you I wrote something up for another comment thread. I'll copy it here verbatim so ignore the stuff about OP's title ;).
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# Important
There seems to be a mix of people using "key" in the cryptographic sense, and "key" in a more layman's sense. This difference is pretty important. In cryptography, a key is for encrypting and decrypting data. It's a very specific thing. People using "key" in this leak are describing a "way" for disabling cryptography.
e: I just really want to emphasize here that the more I read comments around Reddit about this, the more confusing it is because people keep saying "key", "golden key", and "backdoor". In a cryptographic sense, no key was leaked. This does not give a person unobstructed access to the contents of your computer. This does not allow a person to view encrypted data.
## Microsoft didn't actually leak a key
What they leaked is a "policy" that's signed by Microsoft's private key. The policy was meant for debugging purposes and it disables Secure Boot's signature verification. Practically speaking, this isn't very different as far as security risk goes. What this means is that once this policy is loaded, Secure Boot will no longer verify software is properly signed. They made two major mistakes here: they released the policy to production and they signed it with a production private key. If they had actually leaked the key, then attackers could use it to sign their own code and Secure Boot would load it as trusted. Instead, this flaw could allow attackers to simply disable Secure Boot from verifying signatures.
Ultimately I agree with the article's point that this demonstrates why the government's insistence on backdoors is a bad idea. However, it's important to understand that the article and OP's title isn't 100% correct which seems to be a common problem with people talking about encryption.
## Overly detailed ELI5 explanation about what this all means
Just to clear up possible confusion. Secure Boot or this leak is not about backdoors. Secure Boot is a feature that prevents unsigned/untrusted software from booting on your machine. From a security standpoint, this means that it's much harder for a root kit to work. From a business standpoint, this gives Microsoft control over what runs on a machine. For most PCs, Secure Boot can be shut off in your BIOS. Some devices, however, cannot disable Secure Boot meaning they have to run Microsoft signed code.
The simple explanation for how this works is that Microsoft made two keys that are mathematically linked. One is "private" and one is "public." Thanks to limitations of modern computers and what we know about computational complexity, it's not possible to derive one key from the other without some godly amount of computing power. Obviously from the names, public keys are shared and anyone can have them. Overall, they're pretty much worthless to anyone with malicious intents. The private keys have to remain private. The purpose of the private key is to "sign" code, which is then "verified" with the public key.
Signing in this case just means that a small message is encrypted, and verification is decrypting that message and checking to see if it's what we expect. Say Alice wants to send Bob a message saying "Hi, Bob" and she wants Bob to know for sure that she sent that message. Alice would write her message "Hi, Bob" and then hash it (hasing is a 1 way encryption of data, there is no decrypting). She would then use her private key to encrypt the hash, and send it with her message to Bob. Bob would use Alice's public key to decrypt the hash and then hash Alice's message to verify it's from her. This does two things: it ensures that Bob is receiving a message from Alice and that no one interfered with the message at some point. Say an attacker intercepted the message and changed it to "Bob, I need $50 for an emergency" then Bob's hash would not match the encrypted hash.
This technology is just public key cryptography. You use it every day. When you go to a website starting with "https", you're using it. It's how you know the website/server you're attempting to reach is the actual website/server you're talking to. The same principles are used to only run "trusted" code. In the case of Secure Boot, they put this in the firmware of the computer to ensure untrusted software can't boot. It basically does what I described above to only load what it considers is "safe".
The issue here isn't that Microsoft has a private key. Again, **this is completely normal**. This is not evidence of some sort of backdoor or Microsoft being malicious. They have to have a private key in order to sign code. The issue here is that Microsoft couldn't keep the private key, well, private. This is not unheard of. Microsoft has done it before, Yahoo has done it, root CA's (the people that are paid a lot of money to keep their keys private) have done it, DVDs have done it, and BluRay as well. It's not excusable at all, it's a mistake that simply shouldn't happen.
As far as what this means for the average user: not a whole lot. Root kits could possibly be made that overcome Secure Boot. However, this leak doesn't just unlock your entire system for them. They'll still need to exploit other weaknesses to infect your machine. So ultimately, if you don't have another reason, you should keep Secure Boot enabled. Disabling it simply removes *any* protection it might still have.
Is this the end for Secure Boot? Nah, not at all. It's almost certainly not easily fixable and would require BIOS updates as far as I know to revoke the public keys allowing the policy to be verified. I'm still doing some research to figure out how Microsoft can or plans to fix it and I'm not certain if a BIOS update is actually required. If I figure that out, I'll update this post.
e: Maybe last edit. I just want to clarify that when I say "backdoor", I mean it as something intentionally written to purposely enable unauthorized access to some data. This *is* a security flaw and renders Secure Boot effectively worthless, but people saying "Windows 7" is somehow better are basically completely misunderstanding the problem. Ultimately, I think backdoor is a more sensational way to describe what's going on which I don't completely agree with. However, I do agree that this is a good example of why "backdoors" can't be secure in a more general sense but it's far from the only example. So if you read this, please understand that it's basically addressing two separate issues simultaneously. While this is a serious flaw, it's not directly related to the government's push to have backdoors built into devices. |
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If regular soap and water kills germs, why doesn't it lead to stronger strains of bacteria (like we're warned antibacterial handsoap could)? | [deleted] | Soap and water works more by washing germs off than actively killing them. So the bacteria are under less evolutionary pressure to adapt. |
Why is our sky blue at noon but at sunrise and sunset it's red/orange? | It's due to something called [Rayleigh scattering](_URL_0_). Basically, light interacts with the air and scatters. However unlike normal scattering (like you would have with a light in a room), this scattering is proportional to the *wavelength* of the light. Hence higher frequency light (like blue light) is scattered more strongly, while the other colours tend to follow the path of normal sunlight.
When sunrise or sunset occurs, however, there is more air for the sunlight to pass through, and so more scattering occurs. This causes almost all the blue light to completely scatter away and leave us with only the reds and yellows - hence the colours!
EDIT: Wow, I've never had so many replies to something I posted at 2AM. To clear up a few of the major points that I didn't include for the sake of brevity and ELI5:
- By "more air" I mean that at sunrise and sunset, the Sun's light hits the atmosphere at a low angle. [If you trace the path from where it hits the top atmosphere to the ground, it will travel longer to get to you than if the sun were directly overhead.](_URL_1_)
- The sky isn't violet for a few reasons, the big two being that it's scattered more strongly, and so disperses completely before it reaches the ground. Our eyes are also less sensitive to violet than they are to blue - blue light just happens to fall in that sweet spot most of the time.
- The sky turns dark blue at night because it's no longer illuminated by the sun, but rather by the moon... so the same rules apply! This also gives partial explanation to why the moon will appear red or yellow when on the horizon.
Optics is a weird and wonderful thing... more so when you mix a little astronomy in there with it. Never be afraid to ask more questions, or spend a day googling! |
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In commercials, why do they never reference "the leading brand" by name? | Name recognition. They don't want to mention anything in their ad by name that will distract you from their product. |
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Why do you always have to go to the bathroom really bad, when you have coffee with a cigarette in the morning? | [removed] | Coffee is a diuretic, meaning is basically helps push substances through your body quickly. It almost has a flushing effect, id you will. Nicotine (from the cigarette) stimulates and heightens your metabolism, partly why peoole that quit gain weight. Combine the two and thats the experience you'll find. |
How is access to the internet not yet considered a utility, and what would it take for it to become one? | [deleted] | The standard utilities - water and power primarily - are fundamentally services. As a result, they are much easier to regulate at a state/local level. Over time, this meant that they developed organically into public utilities.
In contrast, telecommunications services are non-local almost by definition. So they developed into national level companies that were beyond the ability of state/local bodies to effectively regulate.
This creates two major issues.
The first is that it takes an enormous amount of political will to overcome the vested commercial interests in the field. Comcast and Time-Warner don't *want* to become public utilities and they've got significant amounts of clout to prevent it from happening.
The second is that public utilities don't work very well on a grand scale. When you've got dozens of little utilities scattered across the nation, they effectively provide a balancing effect on one another. If your utility starts becoming inefficient at providing services, you notice pretty quickly because the utility down the road is doing so much better. Moreover, there's a degree of competitiveness on the boundaries of utilities that keeps them in line.
On a national scale, this doesn't happen. You have a single, nation-wide monopoly that tends to slowly be overtaken by rent-seeking behavior. Few people notice because the decline is incremental - and those who do notice are faced with a massive barrier to change in terms of the vested interests within the utility. |
What are Recurrent Neural Networks and how do they work? | Let's back up a bit and talk about decision problems in general. Let's say you want to make an AI that can look at a person's medical records and their current symptoms and determine what disease they have. First, you get a bunch of existing data (patients, with their full medical data plus their correct diagnosis) and train the system.
There are a lot of schemes for how this system would work. One of the easiest to conceptualize is the decision tree, which is in essence just a big flowchart. The trained system asks yes/no questions like "are you over 40?" or "do you smoke less than 2 packs of cigarettes per day?" to narrow things down, eventually arriving at the decision. For training, the computer checks every possible question and picks the one that reduces the chaos the most--that is, the one that most cleanly divides the data points. So if it finds that asking "are you male?" puts all of the testicular cancer on one side and all of the cervical cancer on the other, then it asks that first. For each branch, it keeps breaking things down until the categories are clean enough.
The main "pro" of this approach is that it's really easy to see how the training went, so you can tell if something went haywire. But one of the main "con"s is that in order to train it, the programmer has to understand the problem pretty well. In other words, you can't get the computer to ask the right questions if you don't have a sense of what the right questions might be.
Neural Nets tend to do better in situations where you might not know what the right questions are. [Here's a picture of a small one](_URL_0_). You start with all of your inputs represented as nodes on the left, and all of your outputs as nodes on the right, and some number of "hidden layers" in the middle. Training is pretty complicated, but the basic idea is that you let the system try all possible combinations of connections and explore which inputs are correlated to what outputs.
[Here's a video of a guy who trained a Neural Net to play a Super Mario World level](_URL_1_). The decision tree would be a disaster--it's not as simple as just saying "if there's an enemy in front, then jump". Can you even begin to figure out how a decision tree for this would work? The Neural Net is a great choice because you don't even have to know what the decisions should be.
Skip to 0:48 on the video and pause it. The inputs are everything on the screen, as represented by that box with the beige background in the top left. The outputs are what buttons to press. The nodes in the middle are the hidden layers, and the lines are the "neurons" between nodes. You can see there's a strong connection straight from the block directly under Mario to the "A" button, which is the spin jump. The AI learned that (almost) always spin jumping works pretty well. All of the stuff he says about this approach modeling biological evolution and the human brain is pretty much total BS though.
A "recurrent" neural net is just a neural net where the edges don't just have to flow in one direction, from input to output. They can loop back (or "recur"). |
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why can't we just throw trash balls into the sun? | Or into space? There's a lot more room out there... So, why not? | Because getting stuff off earth into space is incredibly, astoundingly, stupidly expensive and will generate way more trash in the process than ends up in space.
The laws of physics are not in our favour; typically 85%-90% of a rocket has to be propellant, ejected back towards earth to push the rocket into space.
Nasa has [a very good article](_URL_0_) on this. |
The reason diesel fuel is more expensive than regular gasoline. | [removed] | It's more expensive than gasoline in the U.S. and vice versa in European countries because it is taxed higher in the U.S.
Reagan signed the Deficit Reduction Act in 1984 which raised the tax on diesel higher than gasoline. |
Why do our brains favor memorization via images instead of memorization via words? | [removed] | I reckon it has to do with us seeing things with our eyes (and learning/interpreting from that information) for far longer as a species than we have learning or interpreting things through language.
In fact, IIRC, language was only developed far later in the existence of the human species. So think of it as our brains have developed to acquire knowledge far more effectively using images than words because that's what it has done for so, so much longer. |
why does the air in potato chip bags not make the chips stale, but if I leave the bag open later, the chips get stale very quickly? | It's packed with nitrogen which will prevent the spoilage. If it was just regular air, then they would have gone stale. |
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When old pieces of footage for example WW2 are given the HD treatment, how is this done exactly? If the original footage is so poor how do they manage to make it HD? | The original footage isnt poor. Original physical film actually has a very very high quality. Giving it an HD treatment just means scanning the original reel with a really nice scanner. Then they usually go in and repair frames in Photoshop etc that have issues. |
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How does a hacker actually begin hacking? | [removed] | The first thing you do, after you decide who you're going to hack, is ***Footprinting.***
This is gathering all the information you can about your target. Internet WHOIS, DNS information, nslookup data, key personnel, etc.
Next, you need to figure out what IP addresses are actually there and listening. You do this by sweeping a range of addresses and seeing what machines answer you.
Once you know what machines are there, you need to figure out what ports are listening and what software is on the system. Obviously, you can't exploit what isn't there!
Once you know what software is on the system, you can use a tool like Metasploit to find out what vulnerabilities may be present, what attacks might be successful.
After that, you'll need to figure out how exactly to exploit the vulnerabilities you find. That can be overflowing a buffer, injecting SQL into a database, launching an ~~attach~~ attack program...the actual methods used to exploit the vulnerabilities are as varied as the vulnerabilities themselves.
After the exploitation and initial intrusion, you'll need to hold the door open by installing a backdoor so you can get back into the system.
You don't need any special hardware, no. |
What causes someone's eyes to turn red or not to turn red after smoking marijuana | Marijuana lowers blood pressure by dilating blood vessels causing them to be visible in the eye hence the redness. |
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Cinco de Mayo became popular when Civil Rights leaders want to spread Mexican culture. Why do people think it's wrong for white Americans to join in the celebration? | [Wiki article](_URL_0_).
My Facebook is full of people saying how it's wrong to drink tonight, but nobody's been able to explain why.
Tons of non-Bavarian people celebrate Oktoberfest; everyone's Irish on Saint Paddy's Day. Both of them have been exploited by massive beer companies. What's the difference? | Because most people are unaware of why Cinco de Mayo was spread and thus see it as appropriation. Facebook is not the best place to get well informed information.
> Tons of non-Bavarian people celebrate Oktoberfest; everyone's Irish on Saint Paddy's Day. Both of them have been exploited by massive beer companies. What's the difference?
Because those groups are white. Most European ethnicities in the US have been completely homogenized into one white American group. For instance, my Irishness doesn't extend much beyond my name and knowledge of a few Irish prayers/sayings. Therefore, I don't feel any real ownership of St. Patrick's Day and most people wouldn't expect me to. |
How do actors cry on demand--visible tears and all? | Are most that can do this actually just that into their role in the moment? Is that a skill people can practice? | Acting school teaches many different techniques, but some people still can't do it, so those actors often avoid those shots, or they do a trick to make it happen (sprays in between takes).
Some people can think of a loved one who has passed, some can think of a certain song. Some can strain their eyes without blinking for a while causing their eyes to stress and produce more tears, then a couple blinks will sometimes push out enough of that to produce a tear.
I am not an expert in this and these are mostly assumptions. |
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