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cclv5d | Technology | Mobile phone game ads where you can play the advertised game in the ad. How does that work? | It's the same as if you were playing a flash game in the browser. When the ad comes in, it loads this "flash" game, it's a specifically designed ad that allows you to play for 30 seconds and then it turns off to a normal static ad usually | 2 |
ii64wa | Other | Why does an empty/abandoned house deteriorate faster than an occupied but also neglected house? | The interiors of houses aren't meant to have their temperature and humidity cycled hot and cold or dry and wet. It makes the finish materials swell and shrink, which causes cracks. If you don't ventilate the interior in a wet climate, the carpets and walls will grow mold. With nobody home to notice, rainwater often starts getting past the roof and siding via leaks. Water will rot and allow mold to destroy the walls and roof of your house in just a few years. If this happens in winter, you also have the effects of freezing and melting eroding your home. Having people around scares off critters, who would love to live there and chew their way in, making way for water. Also homeless/drug addicts will break into abandoned properties which lets water and bugs in. | 4 |
hg5o4f | Engineering | Is there some kind of storage for electrical power? every country is making their own electricity, but there is probably more of it than the people need. How do they store that remainder? | Short answer is they only make what they need. Yes there is some storage, but it is tiny relative to the amount that needs to be produced. On the grand scale, a grid is managed to ramp supply up and down to meet demand as it changes. That is why it is critical to have a variety of ways of making electricity because not all produce at some time of day (eg, solar), at same cost or with the same amount of lead time (eg, nuclear power plant takes a long time to turn on and save little money when shut down, so usually try to just leave running; burning natural gas turns on/off quick and the fuel is the expensive part so can be used for changing demand). But yes, increasing need for actual storage particularly for solar and wind protects because they produce most of their power at times when demand is not at its peak (peak is evening in developed world when people are at home). Others have answered about a few ways to do that. | 4 |
7o5nfb | Technology | why is it impossible to duplicate crypto currencies and can we do somethimg simialiar with digital movies and games to counter piracy? | Cryptocurrencies essentially work like a very complicated log everyone can read. So you might have Alice, Bob, and Eve playing Monopoly. They start playing but realize that all the money is missing. So, instead they each get a piece of paper and start writing. 1. Bank pays Bob $50 2. Eve pays Bob $10 3. Alice pays bank $20 4. Alice pays Eve $30 5. Bank pays Bob $20 Every time someone pays anyone anything, everyone writes the transaction down, and makes sure that the transaction is valid. If the transaction is invalid (Someone notices that Bob is trying to spend more money then they have) then they won't accept the transaction into the ledger. Because everyone is paying attention to what you're spending, and everyone can calculate exactly how much money you're supposed to own, nobody can cheat by spending the same money twice. If you try someone will point out "Hey! You already spent that money paying the bank!". This isn't really feasibly for DRM in the current form, because it's a solution to a different problem entirely. | 2 |
kxpe0p | Engineering | Why the wheels dont move as sync as the crankshaft in a car? I've been wondering, when 2 gears are set together, one moves proportionally to the other gear(number of tooth etc) but the wheels on a car dont behave the same. the wheels build up the speed in time while crankshaft is spinning at the same RPM. Why is there no broken gear tooth? | In a manual transmission cars, they do as long as you don't engage the clutch. The crankshaft engaged the input shaft in transmission gears and then goes to output shaft and the differential then the axle and the wheel. In automatic transmission cars, the clutch is replaced by a torque converter which allows some slip before engaging the transmission input. Your description more matches cvt cars, the transmission is constantly changing gear ratio to make "good fuel efficiency" so your engine rpm might stay same while wheels spin faster | 1 |
6oa0m3 | Physics | Whem pouring liquid from one container to another (bowl, cup), why is it that sometimes it pours gloriously without any spills but sometimes the liquid decides to fucking run down the side of the container im pouring from and make a mess all around the surface? Might not have articulated it best, but I'm sure everyone has experienced this enough to know what I'm trying to describe. | let's pretend that water is a bunch of people. These people don't want to let go of each other- they're scared of what will happen if they fall of the edge of the world. They stretch out their hands, crying "Hold me! Save me!" Some people, when they're at the edge, try to hold on with all their strength and get dragged along for the ride. Others, however, are too weak or afraid to hold on, and let go. Unfortunately, once someone has let go, there is no going back, so once everyone has let go, the unfortunate people fall into nothingness and are lost forever. But while there are still people stretching out there hands, a few of the people who have already fallen still have an opportunity to get ahold of the cup, or the bowl, and hold on for dear life. Meanwhile, the people that are falling beneath them are swinging back and forth, like Tarzan on a vine...and then they fall. P.S. I'm still working on this "talking to 5 year olds" thing. They're crazy insightful but also horrendously naive. | 13 |
9zu8gs | Technology | Before MIDI, how did musicians time the beats exactly right? When I listen to something old like Thriller, I notice that the beats of the drums seem to be timed exactly right with the rhythm, with the same amount of time between each beat. Or so it seems. Because now, with MIDI, you can have the instruments timed to be exactly right with the rhythm, but Thriller was made before MIDI, and now I'm wondering how the drummers and musicians played their instruments exactly on beat and to the rhythm. There's a website called Got Rhythm where it tests to see if you can maintain the tempo/rhythm of a drum beat even after it fades away, and it would always tell me that most of my beats were slightly off tempo. Now I'm wondering how musicians timed things to be exactly on tempo before MIDI. | Don't forget, Michael Jackson had the ability to pull the best studio musicians possible. Some are better than others, and since he could afford the best, he had the best. And the best have a great internal sense of time. | 4 |
9ys1vs | Technology | how does a gif or a jpeg lose pixels as it gets shared more and more? When you copy it doesn’t it copy the whole file? | If you just copy the file to someone else or a different storage location, then no, it doesn't lose anything. However if you do something like opening in an image editor and resaving it then it goes through another cycle of encoding, possibly losing image information depending on the compression factor applied. | 3 |
bpzzub | Economics | Why is it so crucial that a public company continue to grow at all costs? What’s wrong with sustaining profits? | There's nothing wrong with having a business coast along at its current level of performance. Ultimately its the up to shareholders to decide what the companies goals are and those goals might not be served by expanding. But public companies shares are bought and sold openly and are only really thought of as investment. So the company serves its shareholders and public shareholders in aggregate only care about their share value and profit dividends. So without high percentage private shareholders (eg, the founders) the companies only real goal is to become more profitable, which requires continual expansion into new domains as you can only do so much within a single field. For a simplistic example, what happens once everyone has bought your widget, when everyone uses your service? You need to either find a new market to sell it too or come up with something new to sell, hence you need to expand, to continue to grow your profits. | 3 |
ch80bj | Biology | Why do humans have such vastly different personalities, even though biologically we are all “wired” very similarly? | Because we aren't wired the same. Think of it like houses. While they look the same, they have a roof, some walls, a floor, windows, they are not the same at all. | 5 |
5txyhw | Culture | The events leading up to National Security Advisor Flynn's resignation. | I wonder what if anything he may have said about this formally to Congress. It is a felony offense to lie to Congress concerning a material fact or in a false writing under 18 USC 1001. No idea if there is any indication he made any such false statement -- but if he did, consequences are more than just ethics violations. Kudos to WaPo for dogged investigative reporting. | 3 |
c42nzx | Other | How do TV stations know how many viewers they have for their ratings? Isn't it just a signal that is being wirelessly broadcasted? | an expert will give better insight. but short answer: They dont.. it was all survey/research based. ( [ URL_0 ]( URL_1 ) ) it was done to the best of capabilities all over world. sometimes automatic . sometimes manual. it would be seen at what times what channel is being watched. and a calculated figure was attained | 2 |
kjr2s9 | Biology | how closing our eyes helps heighten our other senses. | Basically what the other commenter said, a useful way to utilise this overstimulation filter is if you ever hurt yourself, stub your toe, bang an elbow etc, hurt yourself purposefully (and safely) for example by pinching your skin or slapping your leg hard and the injury will feel less painful. | 2 |
ecpdf5 | Biology | What makes flies important to the ecosystem? | Smol critters are the snack foods of the ecosystem. Flies (specifically their maggots) help in the decay of dead things, other files pollinate plants. The flies in turn support other insects that eat them - their predators are eaten in turn. & #x200B; Diseases and parasites are just hitching a ride on the flies. | 2 |
6osnwk | Culture | Why are humans attracted to the foreign? My football team, based in a non-native English-speaking country, had a loan exchange with an English club. One of their players joined us on loan, and one of our players joined that English player's original team. When we went out on weekends, girls flocked this English guy as if they had never seen a guy before. It was very fascinating to see somebody giving zero effort and still succeed. Simultaneously, our player on loan in England claimed that he had the same situation where we was. Why is this the case? | Biologically, animals are attracted to members outside their clan to increase their gene diversity. It decreases the odds that your children would be born with 2 recessive genes for any trait. If humans didn't keep records or strong family ties, and you just met the cute girl down the street that looks similar to you, how would you be sure she wasn't your second cousin? | 2 |
d6umue | Technology | How do phone companies release phones that are so similiar when they have 2-3 years in development behind the scenes? the new iPhone 11 and google pixel 4 both have the camera clump in the top left. As-well as with the S8 (?) and the pixel, the finger print scanner was moved to the back. So many companies ditched the headphone jack within the same year. along with so many other changes that happened in the same year. How does this happen? | Phone development is spurred by consumer wants. Because most consumers look for the same things, they design phones around those. Ditching the headphone jack could also be seen as a money-making opportunity. Companies have only ditched the headphone jack when they are successful in selling their own wireless earbuds. | 1 |
j7lxct | Technology | How does CGI work? Do you have to draw whatever it is frame by frame? | "CGI" is an incredibly broad term. It is imagery produced by computers, which can be anything from cartoon animation, 3D stills and animations, digital effects in conventional movies, and a bunch of stuff I can't think of right now. All that said typically a major benefit of using computers is that you don't have to manually draw every frame. A cartoon animation for example might be able to take a line an animator placed in two different locations and extrapolate where it should be in intervening frames. Or a 3D animation uses the models/textures/paths produced by the animation team and the computer renders how it actually looks. "CGI" certainly isn't just a bunch of guys painstakingly painting every pixel on their own. | 1 |
elhkyq | Chemistry | What is half life, and why is it important? I’ve been through both high school and college chemistry and yet I still don’t quite understand what half life is, why it happens, or what it’s used for. I know it involves radioactive elements and decay and stuff like that, but I don’t really get what that means either. | Half-Life is a FPS game developed by Valve and published by Sierra Studios for Windows in 1998. It was Valve's debut product and the first game in the Half-Life Series. Players assume the role of Gordon Freeman, a scientist who must find his way out of the Black Mesa Research Facility after an experiment with an alien material goes wrong. The core gameplay consists of fighting alien and human enemies with a variety of weapons and solving puzzles. Unlike many other games at the time, the player has almost complete uninterrupted control of Freeman, and the story is told mostly through scripted sequences seen through his eyes. | 5 |
io2wdg | Biology | Why does saliva taste like blood when you exhaust yourself? Why does your saliva start to taste like blood if you ride your bike up a hill or run fast for a while? Edit: Thanks for the Awards and the nice Comments. Also blew up bigger than I thought! | I have low potassium and magnesium and it tastes like penny's, I get muscle weakness, it feels like my legs are cooked noodles, and they get very heavy. Talk to your doctor about a blood test. But its probably something else. | 22 |
ex2c5m | Other | Why do they send fire trucks with ambulances when there’s no fire? | firefighters are trained and equipped for extractions and rescues. Paramedics are not. I don't understand either why fire trucks and firefighters show up to a routine medical call (heart attack, broken leg, stabbing) but for any sort of accident they may be needed. | 6 |
6qp8az | Chemistry | Why is a 2 degree Celsius increase in temperature on earth considered dramatically dangerous. Every time I read about climate change, many articles talk about the year we will reach a 2 degree Celsius increase, but I’m not sure why that number is so important. What happens at that point? | Try to imagine all the matter that makes up the surface of the Earth. All that air water, earth, rock, etc. To increase the average temperature of all that involves an immense amount of energy. It's the air in particular that's a cause for concern. Air that's 2C hotter is more energetic and can hold more water vapour, which means that storms will be stronger and rain will be heavier - or both at the same time, in the form of more and stronger tropical storms and cyclones. There are millions of people in situations that are highly vulnerable to this, such as just about the whole of Bangladesh and its > 160 million people. [It's happened before] ( URL_0 ). | 2 |
7ge1zl | Economics | If I sell stock, who buys it? | Whoever wants to buy it. If nobody wants to buy X stock, you can't sell it. There's just so many transactions going on constantly, unless you're trying to sell a large quantity of a stock (especially not a popular one), you'll never run into a situation where you don't have a buyer. | 2 |
k4ufy0 | Economics | Why do companies have different names depending on their geographic location (i.e. Hardee’s vs Carl’s Jr, Dreyer’s vs Edy’s)? | Hardee's tried to expand to Canada where there is already a nationwide burger chain called Harvey's. They were forced to use the Carl's Jr. brand, as the name was too similar. | 2 |
jmx3ad | Biology | How does the body recharge itself after sleeping? Basically, how do we regain energy/ recharge so we aren’t tired throughout the day after a good rest? | When you sleep, your body switches certain systems to “low power” mode while ramping up others. The main system that powers up is called your parasympathetic nervous system. Very briefly summing it up...this system works on healing any damage you sustained during the time you were awake, as well as allocating resources to be prepared for use the next day. The more you sleep, the more healing is done and the more energy resources your offline system has had time to put in place. Thus, you feel awesome the next day. | 4 |
mktjfd | Chemistry | -Why do you feel that 'coldness' after using hand sanitizer Self-explanatory | because alcohol evaporates so quickly, when it evaporates it cools your hand or the surface its on using evaporative cooling. | 4 |
ar7u1o | Physics | Why are rubber gloves almost impossible to put on with wet hands when water usually makes things slippery? | Because of [wet friction ]( URL_0 ). Rubber and latex are soft, flexible materials, as they stretch out, surface area increases, increasing friction. Normally with dry hands. The rubber molecules have few places on the skin to bond to as it slides past so there is little friction. Water on the hands fills all the little cracks and lines on the hands, bonding to the skin. The rubber then bonds to the surface molecules of the water, as the surface area of the rubber increases, so does the friction, until you cant slide your hand any further upwards and have to peel the glove off | 1 |
jkv03f | Biology | Why does working out stops overthinking/rumination? Since I have started working out and I have noticed that all of my overthinking stops and I stay more in the present moment and not in the head.But when after sometime I stop working out I again get in the fantasy land/overthinking/negative thoughts.Why is that? | So one hypothesis is that when you aren't doing anything your brain has this cool feature where it will replay mistakes you made or embarrassing moments. To remind you of them so you improve on them to not make that mistake again. It's like in the past if you walked in the woods and got attacked by a bear and survived. Your brain will replay this so next time you will notice that there were paw prints and claw markings so you don't make that mistake again. Like how in sports they rewatch the tape of their games to learn how to improve. And this is why many of these thoughts happen at night because you aren't doing anything in that moment so the brain thinks to turn on the replay to make use of that dead time. But now you are improving, you're working out. Now instead of replaying the past it's focused on recovering from your work out and getting stronger and healing and adapting to the new activity you're putting it through. | 2 |
8vxefc | Economics | Why do some manufacturers print their own prices on items? | Arizona does it because it's one of their core marketing points. They're trying to place pressure on retailers to sell it at that price. Other companies, like chips , do it for convenience. It's a lot easier for them to print a price on the bag than it is for the store to put a price tag on it & crush all the chips. A store can always mark other prices or buy unpriced merch. | 3 |
8e107d | Biology | Why does water have a relatively neutral taste? | Taste researcher here. There is some debate over whether we have a specific way to detect water. Clearly we can tell water apart from other liquids, which is clearly useful... Water is essential to life. We may be able to detect water because when water enters the mouth, it dilutes the concentrations of the ions in our saliva, which we might be able to detect (e.g. when the water dilutes our saliva, the sodium concentration decreases, causing sodium receptors to be less activated than they would be when there's only saliva in the mouth). Fundamentally, however, it could simply be that we simply can detect water because (almost) anything other than water will have a taste we can identify. So anything that we drink that does not have an identifiable taste/odor is assumed to be water. | 4 |
hmxw4j | Biology | Why are powerlifters not lean? Wouldn't lean mass be more beneficial for lifting heavy? | When you lose weight, your body burns fat and reduces muscle at the same time, because it takes a lot of calories to maintain the extra muscle mass. So while dieting to lose fat is done by most people who lift weights to look good, people who care just about maximum strength don't do that because they will lose strength in the process of dieting. | 2 |
enyoiu | Biology | Why are there no horned predators? Unless theres some I havent heard about, but no preds (or at least carnivores?) seem to have grown horns. Why is this? e/ I appreciate people who pointed out fish but I was mostly talking about land animals, shouldve been more specific oops | Horns are defensive, predators need weapons that are able to be rapidly deployed for maximum damage. A predator with horns chasing down a rabbit for example would be hindered by the horns getting caught in branches etc, or scraping on the ground whereas an animal being chased by a predator can use the horns for defence. | 4 |
flrxaw | Biology | How can cows eat nothing but grass but still grow to be hundreds of lbs of muscle? | Grass, like all things made of cells, has fats and proteins and carbohydrated and basically everything else we need. Nothing on earth can be alive without being built from hydrocarbons and amino acids. It just happens that grass is much harder to digest. It's the same reason why celery is a "negative calorie" food. It HAS calories and carbs and proteins, but it takes too much work to extract them. | 17 |
bddr6h | Biology | How do people imagine things in their minds? | I have no problem “seeing “ things in my mind, I also have no problem visualizing -or- vocalizing stuff mentally like books or lyrics...but I can’t hold numbers in my mind ☹️. Mental math, even simple 3 digit addition is pretty much impossible for me. It’s like dyslexia but for numbers. I managed to make it through school with it not making a major impact but it has very much affected my life. I couldn’t do my current job if I couldn’t mentally picture things then recreate my vision. | 20 |
6ot9dw | Biology | why does water sometimes feel like it's stuck in your throat when swallowing so it actually hurts, then the next swallow is normal? | You have 3 anatomical normal constrictions in your gullet and if you swallow an amount of water that can't pass directly thru the first of these constrictions, the muscles of the gullet are contracting normally and try to pressure the water thru this constriction. And because it can't pass all in the same moment there is a big pressur on this constriction which is causing the pain | 2 |
o8rjy9 | Physics | Some insects and animals have the visibility range that includes IR and UV Rays. How can we imagine the visibility to look according to humans even though we can't see them? | Some humans don't need to imagine. We have cells in our eyes called "cones" that are sensitive to different ranges of wavelengths (which we perceive as colours). Broadly speaking, some detect red light, some green light, and some blue. Combinations of these give all the colours a typical human can see. Ultraviolet light can be detected by the cones, but it is blocked by the lenses of the eyes. Some patients born without lenses (a condition called aphakia) or who have had operations to remove cataracts, in which the lenses are replaced, report being about to see UV light and say it looks whitish blue. As an aside: all humans with regular eyesight can see UV light... sort of. Laundry detergents that contain optical brighteners convert normally invisible UV light to visible light, and so make white clothing literally "whiter than white". | 3 |
617d3d | Repost | Why were prehistoric creatures so much larger than creatures of today? | There are a couple of theories. In the Paleozoic Era, there seems to have been more oxygen in the air which allowed for massive insects. Being larger also can have evolutionary advantages. Larger animals are harder to predate. But as a result, the predators also grow bigger. A third theory is that shifts in temperature has some effect on size, as temperature has an effect on metabolism. | 1 |
8v7eme | Economics | How can companies afford to do things like sales and clearances? Don’t they just lose money? | Also most items are incredibly marked up.. They receive those goods for a MUCH lower price than what they sell it.. | 3 |
f20v6s | Other | from the moment my town picks it up, what happens to the soda can, glass bottle and stack of papers I’ve recycled? | Cleaned, broken down to base material and remade into new products. Glass and aluminum would be melted, while paper probably shredded and soaked, pressed, and dried into new paper. | 9 |
akgpya | Other | why are more people depressed today than ever before even though life's quality has never been better( at least in western countries) | Hunger and anxiety work in a similar way. When your stomach is empty there is a nerve at the very top that senses pressure and tells your mind "I'm not full". It's okay to not be full. But over time, if not satisfied — you get hungry. And if you don't fill your stomach for long enough, you will get hungrier and hungrier. This evolved system was designed for people who mostly eat low calorie stuff like plants they find. Your stomach doesn't know *what* you eat. It just directs your mind to be concerned that it isn't full. So if you eat a large salad, you can satisfy the full feeling. But if you eat a lot of very small, high energy things with a lot of sugar, you can get fat while still feeling hungry. Anxiety works the same way. Your big brain burns a lot of calories. So we evolved to make good use of it. We evolved to use our brain to worry about things attacking us, or worry about whether we have enough food for the winter. Or worry about whether our neighbors are plotting to kill us and take our food. We have a sense in our brain just like the sensor in your stomach that detects when your concerns are empty and says "hey you should probably be worried about stuff". So you start filling your mind with things you really do need to worry about. And you feel satisfied. Worried, but also satiated. But if you don't actually have something satisfying your mind can find to engage itself in worrying about, you never activate that concern sensor. You never feel full in a satisfying way. If you never satisfy the impulse, it grows louder and louder. That worry about things to worry about is called anxiety. This is one reason TV shows require conflict. It's satisfying to watch other people's problems. It satiates our desire for things to worry about. **So what does anxiety have to do with depression?** Habituation. Depression is *habituated* anxiety. *Habituation* is a term that describes something our nervous system does in response to overwhelming, constant stimulation. Why don't you feel your clothes pressing on your skin nerves all day? Habituation. Ever get that sudden ringing in your ears—that high pitched tone that starts and then maybe a minute later begins to fade away? That's one of the small hairs in your ear the ties to a sensory nerve dying and falling out. Upon falling out, it triggers the nerve permanently. That nerve will signal your brain to hear that tone forever. The reason it stops is because your brain adapted to the constant signal by turning it out forever. And it works on more complex signals and patterns too. "Anxiety". Repeat it 10 times. Anxiety. Anxiety. Anxiety. Anxiety. Anxiety. Anxiety. Anxiety. Anxiety. Anxiety. The word sort of falls apart doesn't it? It loses its meaning when repeated often enough because your brain is beginning to tune out. Normally, hearing a word triggers thousands of nueral circuits to activate. As your brain gets over exposed to it, even these complex reactions can get habituated. This is called **Semantic satiation**. And it happens on even more complex systems like our concerns. Constant anxiety signals will habituate us to them. And over time we will learn concern satiation. We become numb to all our concerns. Remember, depression isn't just sadness, it's a lack of interests. *Anhedonia* is the condition of having no interests and concern and interest are very closely linked. So eventually our inability to satisfy our concern appetite leads to concern satiation. And that's why people with fewer instinctive concerns are the most depressed. | 6 |
8jb7v7 | Mathematics | Why does 360° make a full circle? Why isn't it a round number like 100? | Circles are also inherently related to 6. 6 circles equal circles will fit around a circle of the same size, and some cool tricks can be used from there to define the Platonic solids. Look up Metatron’s Cube to see how that works. 3 was once used as an approximation of Pi, which is another number that will divide 360 but not something like 10 or 100. | 16 |
hz5duj | Physics | How does a thawing tray help to speed up the rate at which food defrosts. Or does it only convenience it with then clearing of water. | A thawing tray essentially allows heat to transfer into it from the atmosphere so that it can transfer into the thing you're trying to thaw faster. Air is a poor conductor of heat, so it doesn't really allow the heat from it to transfer into a steak or chicken breast that quickly. Metal is a better conductor, so it allows the transfer much faster. The material of the tray also allows the heat to transfer within itself much faster. This means that when the center gets cool, it almost immediately starts spreading to the edges. You now get to take advantage of the whole surface area of the tray to pick up heat from the air so that it can continue to transfer it into the frozen food. | 1 |
bemxo8 | Other | Clouds are made up of water that has evaporated, in Summer when it is hotter and more water is evaporating there is often far less clouds than in Winter when it is cold and there are lots of clouds. What causes this? My head hurts trying to think about this... | Water vapor needs a surface to clump around and become a liquid rather than a gas. The relative humidity (how much water is in the air) needed changes with temperature. You need more water in the air to make clouds in warmer weather. The process is called deliquescence | 3 |
5wd2d1 | Culture | How did the color blue and pink become associated with masculinity and femininity (e.g. newborns are wrapped in blue or pink blankets from the get go)? | From the Smithsonian, [When Did Girls Start Wearing Pink?]( URL_0 ). The article provides sources for many of the comments others have provided. | 17 |
ck265w | Technology | What are neural networks? | The term is used loosely to describe a variety of schemes by which large amounts of data are mathematically manipulated to perform classification. Imagine for a moment there's a large stretch of woods surrounded by various homes and businesses. Now, no one really wants to walk around the entire stretch of woods just to grab a Slushie. So they walk through the woods instead. When they do so, they trample the soil and bend the brush out of the way. As more and more people take their own route through the woods, you'll quickly see 'paths' develop along the most common routes. Those paths are actually a form of information. If you find a path in the woods, it's connecting one thing to another. The existence of that path tells you something about the relationship between its two endpoints (even if that something is nothing more than "Bill likes Slushies"). That's basically what happens in a neural network. You have complex mathematical structures that are trained in some fashion to have such 'paths' through them that allow you to feed a large amount of data in the front end and get a classification out the other. | 4 |
f3w3df | Economics | What's Wrong with Negative Interest Rates So I've been reading an article on AP about negative interest rates and it really didn't seem so bad. There were a bunch of quotes in it that basically sounded like "NEGATIVE RATE BAD!! SCARY!!" but without actually having any content pertaining to the possible risks. It seems totally intuitive to me that you would do this if you wanted to punish people for huddling up avoiding investment and keeping every cent in the bank instead of stimulating the economy. It also seems like an efficient tool for battling capital strikes. What is the massive risk that people are afraid of there? Edit: I am talking about a negative interest on excess reserves. | With negative interest rates there are no incentives for banks to lend money since there is no return this unless is is government funded. But if it is not banks will lend no money at all and there will be less consumption/investment in the economy worsening economic growth and unemployment etc. | 3 |
lp4t4o | Engineering | The Texas power grid was supposedly seconds away from a months-long power outage and complete collapse of the power grid last week. What does that mean, and how is that possible? | It's important, in a grid power system, that the generating capacity and the electrical load are balanced to one another. There's a scenario called "cascade failure" which is very bad. If one of the stations on a power grid fails unexpectedly and stops providing power, then all the systems that are plugged into that system are still trying to draw the same amount of current, but they're drawing it from fewer generators. This loads those generators more severely. And if they were already operating at the edge of their capacity too, then it's more likely that one of them will respond to the load spike, by failing too. And the more stations that fail, the worse the load imbalance becomes for those still online. Like I said, this situation is very bad. In the best case scenario, failsafe systems will just shut the generator down when overloading like this. But if that doesn't happen, there can be all kinds of damage to the system and it might not be safe to start up again until that damage is addressed. To avoid this situation, one of their last resorts is called 'rolling blackouts', where they simply disconnect bits and pieces of the grid to try and keep the load balanced. | 5 |
mg7l1h | Technology | How are metal forges made if you need to forge the metal they're made of? Or rather how can equipment that's made to work with very high melting temperature metals be possible to make? And if there is some non metal material that is used for forging high temp melting point metals, why not just use it for everything? | It's only until people start smelting iron that forging is needed. Metals like copper and bronze can be melted and cast into forms in order to get hammers, anvils, and other metalworking tools. Iron has to be forged though since melting it to make tools is impossible if the best heat you can get is charcoal. The first iron workers already had bronze tools to work the iron metal that came from the smelter. That works just fine since even though bronze loses strength and melts at lower temperatures than iron, the hammering and shaping isn't done in the heat of the forge and the tools aren't in constant contact with the hot metal which keeps them from heating up. The same idea is how we can use steel machinery to shape white-hot steel into whatever we want. The steel rollers, cutter, etc don't continuously touch the hot steel. Technically, the roller as a whole does, but any one part of it spends most of its time not touching the work material which limits how much it heats up. | 5 |
jfyq2u | Chemistry | How do scientists calculate half lives for the elements that have super long ones that we can’t observe? I’m sorry this is probably dumb. I’ve just always wondered :) | We can't observe it decay by half but we can observe it decay a little bit and with some math we can then figure out what the half life must have been to go from Quantity A to Quantity B over X days If you start with a hunk of a material and measure how many particles per second are coming off of it, then wait a week and measure it again. You can rearrange the standard half life equation (Amount at time t = Initial Amount * (1/2) ^( t/half life) ) to get HalfLife = 1 week * ln(2)/ln(First Amount/Amount at 1 week) For things with really longggg half lives you might need to measure over a couple months to get a big enough difference between the two amounts to get a reliable answer, but the point of modeling things with math in science is so you don't need to observe a complete event to know how it will turn out | 4 |
6a98k3 | Other | How does flash flooding happen? I always hear stories of people dying in flash floods. Does the water really come that fast? How do people not know? | Here in Las Vegas, the land is baked by the sun for most of the year (we receive about 4 inches of rain per year, with only 21 days out of 365 with rain). It's very hard because there is no moisture, and the little that does fall tends to make it like hard clay, rather than topsoil. We're also in a "bowl" with mountains on all sides sloping down into a valley. Rainfall here tends to be like 10 minutes of torrential downpour, and then it stops, rather than just sprinkling all day. So this large amount of rain in a small amount of time doesn't soak into the soil at first (remember, it's hard like clay), and it all runs downhill into the valley like an avalanche. As far as people not knowing, you should be aware if you live in a flooding area. An insurance company could tell you, and cities are constantly shifting where the flood zones are. | 1 |
drocpq | Technology | How do big companies like Amazon that have customer support Twitter accounts handle all the tweets that they get by the minute? | My fiance does this for a living for one of the huuuuge companies (she does mostly Instagram, but the software does Facebook, Twitter, insta, YouTube). Her company runs CS phone banks and email services which they contract with corps to handle on their behalf. Social media team's are considered the advanced positions since they have more latitude with responses. Basically there is a team that gets the incoming messages in a program, and her team's full time job is to tag each tweet, and send an appropriate canned (usually) response. Different brands have different "voices". They have authority to hand out coupons as apologies and such to a certain extent, have to do medical documentation for medication complaints, and refer to specialists when needed. Mostly it's just fun feedback (i.e. " your baby is soooo cute!" or "sorry to hear that, here is a coupon for a new item since that one was faulty"). She has a video conference with each brands marketing team on a regular basis, and works from home on her laptop. Pay is in the teens per hour. | 3 |
o5ht5x | Other | Why do spices in your cabinet get hard?? And what’s the best method to soften them back? | If ground spices accumulate moisture, they will form clumps and harden. The best solution is to keep them in the fridge so they will not break down. | 3 |
5u9ry1 | Engineering | Why is there a little bulge on top of the positive terminal of an AA battery? | It's so you can get the best contact with both sides in the simplest way. Since the negative side is flat, you can place a spring of some sort on that end and not risk it slipping off. Because the positive nub is smaller, it's concentrating the force applied to the back end by the spring onto a smaller area, ensuring good contact on the positive end without needing a second spring. Since there's only one spring, it's a lot simpler to load than if you had two springs pointed opposite directions. Also it's easier to show pictorially that "the side with the nub goes here" than "the positive side goes here" to someone with zero knowledge of how electronics work or that there are positive and negative charges. | 1 |
m0zwb3 | Engineering | What is the entire process of my connection to a website with a server halfway around the globe? I know that we use radio waves to connect to the modem, but then do the wires run ALL THE WAY across the country, through the ocean, and to the country halfway around the world? And if so, how does that happen in 1-2 seconds? | There are cables under the oceans that can communicate using light. The speed of light is able to circle 7.5 times around earth in 1 second and that's how it is able to communicate in seconds. An simplified overview would be Your computer WiFi- > LAN to your Internet provider - > underwater cable to the Internet provider for the website - > LAN to the Website's building - > Website's WiFi Edit: Typos | 3 |
8q5rcq | Biology | How come some zits build back up with puss the next day, even after you squeeze everything out | Puss is primarily dead white blood cells that have died in service killing an infectious bacteria. If you squeeze it out and it fills back up with puss it's because the infection isn't contained yet. If it's a black head then it refilled with oil/dirt before the pore closed up | 2 |
7e5kk3 | Biology | What is protein folding and why does running simulations of it take so much compute power? | Proteins have various structural layers. * Primary structure is the sequence of amino acids that make up the protein * Secondary structure consists of so-called 'motifs' like alpha helices, beta pleated sheets etc, which are how local regions of the protein fold together * Tertiary structure is the overall 3-dimensional shape of the protein * Quaternary structure is used when proteins have sub-units and refers to how they fit together There are lots of different types of proteins but I'm going to use enzymes to start off with. Enzymes are proteins that cause another chemical reaction to happen or to happen faster. They mostly have a part of themselves called the "active site" which is where the interesting chemistry happens. The Holy Grail of protein chemistry is being able to predict the tertiary structure of a protein from just the primary structure ie. given the sequence of amino acids, what does the final protein look like. If we could do this, it would have huge implications for drug design and treatment of some diseases. The problem is that there are lots of different ways that proteins can fold because the amino acids themselves like to interact. One of the simplest is the formation of disulfide bridges between cysteines in the protein chain. The primary structure might contain many cysteines but only a few of them actually link up and the cysteines that link up might not actually be close to each other. So the more cysteines you have, the harder it is to predict the final structure. But that's not all. There are many, many other ways that proteins can fold. They can form hydrogen bonds between amino acids, the secondary structure can constrain folding or there can be subtle Van der Waal's bonds between portions of the chain. What this all means is that the folding of proteins is an incredibly complex process that is not easily predicted at all and becomes virtually impossible once you get to a protein of any significant size. On top of this, some proteins actually have multiple stable folding states. Often these proteins can change their tertiary structure based on some internal chemistry eg. an enzyme can change its structure at low pH to expose the active site while at higher pH the active site is closed off. So even if you can predict the tertiary structure, it's hard to know if you've predicted it correctly. | 2 |
6dpt0s | Engineering | Does cambering your car wheels actually have any benefit? I understand that the extreme camber that is the new fad probably doesn't do anything beneficial and most likely is counter productive. But is there a reason to camber your wheels more that required to keep them flat on the road? | A tiny amount of negative camber helps during high speed turns where all the weight transfers to the outside wheels and the tyres deform by a degree or two. F1 cars typically run with 1, maybe 2 degrees of negative camber to keep the tyre wear from cornering more even (and hence last as long as possible before needing a pitstop). If you're not driving in a way that involves tons of lateral G-force then it's not worth it. | 2 |
ahhg0f | Mathematics | What’s keeping weather forecasting from being a highly accurate science? We’re expecting snow where I live and forecasts vary wildly. So, what’s the roadblock keeping meteorologists from being far more accurate? (No snark or judgment on the profession here, truly curious) | Weather is a chaotic system. Small changes tend to produce large differences in outcomes. The models that meterologists use take this into account and provide an error margin. This is what you see in storm tracks with the cone of uncertainty. The farther out, the less reliable the predictions become. Since they cannot collect enough information to accurately measure every single variable, they are estimations and the accuracy of those estimations can produce wild swings in the predictions. Weather services are constantly updating their models with newly gathered information to refine the predictions. Those new predictions can be accurate to about 3 days with good confidence. Past that, confidence goes down and more uncertain predictions result. If you want to know more, you can look up Chaos Theory. | 3 |
id6tea | Physics | Why are air and water transparent? | The air is not completely transparent, it's the vision that has formed to see [wavelengths it is transparent at]( URL_0 ). Also, since air contains water vapor and oceans contain dissolved atmospheric gasses and only get lit by the light that has already passed through the atmosphere (bioluminescense doesn't count), their transparencies correlate strongly and the creatures who developed vision before walking out of the sea were able to see through the air as well, not just the water. | 2 |
hclxbh | Technology | Why do black and white pictures that were take like 40-50 years ago look so clear(like an hd image) | You ask about black and white pictures, but you don't mention color images from the period. I don't know if you are contrasting the black and white pictures from the color pictures of the time, since they are often faded. If so, the reason for the fading of color pictures is that the color is provided by special dyes or inks in the paper, which interact with the light. Dyes and inks are fairly complex chemicals and can break down over time when exposed to ultraviolet light (from the sun, for instance), causing them to fade. This is the same thing that can happen to fabrics or paints that are left in the sun for a long time. Black and white photography does not use dyes but instead uses silver. Black and white films and papers have a chemical compound of silver in them. When exposed to light, this compound would change so that, when it was developed, the compound would leave behind tiny grains of silver. Where it wasn't exposed to light, the compound would just wash away, taking the silver with it. The silver left behind looks black to us. Since it's just silver, it doesn't fade over time because there really isn't any way for it to break down. | 8 |
9xtzrr | Other | How can you visualize something if it's higher than 3 dimensions? | You can't. Hardly anyone does in its natural state at least. What we do is, transform a higher dimensional object into 2D and see only some parts of it at a time using some reasonable geometric features. | 1 |
5ofteo | Chemistry | Can you predict the time it will take for water to change to a certain temperature, based on the temperature around it? If I have a gallon of water in a glass jar that is 100ºf and I leave in in a room that is 70ºf, is there a mathematical formula that can tell me how much time it would take for that water to reach a specific temperature? | Yes, you would use [Newton's law of cooling]( URL_0 ), set it equal to the temperature you want, then solve for the value of t. The constant *k* is something you would either need to look up, or solve for yourself by taking two temperature readings at two different times. | 1 |
7sosjz | Engineering | why we can't (easily) convert ocean water to fresh water? | We can, but it is fairly expensive to setup and maintain, and would also only help areas right along the coast without also investing in infrastructure to transport this water. Desalination plants do exist, but taking the salt out of water through normal means (typically by boiling most of the water which leaves behind a salt-rich brine while the water vapor condenses into pure water) is really rough on the pipes (the salty brine is fairly damaging due to the salt deposits it tends to create). So they require a lot of maintenance. | 2 |
a7q4v0 | Physics | How exactly do we know how old the universe is and when the Big Bang happened? | When we look at a star at one point in the year and plot it’s position, then look at it again in six months and plot it’s position, we know how far away the star is from us because of geometry. When we look at that same star, we can see what color it is, and we see how certain colors of light are absorbed by gasses surrounding it. We know hydrogen absorbs light of a certain color, maybe blue (doesn’t matter). But the characteristic “absorption line” doesn’t show up as blue, it shows up as purple. That’s weird - the light is shifted towards red. That redshift happens because the star is moving away from us. We can measure the redshift and calculate the speed of the star. With position and speed, we can sort of mathematically “rewind” the stars motion, back to right before “the beginning” - we call that starting point the Big Bang. We don’t know how large the universe is. We know how far away the oldest light is that we can see. So we know the size of the *observable* universe. | 1 |
8puido | Other | What would happen if theoretically an astronaut was to die in space at the beginning of their trip but the rest of the crew was still alive? | Real answer: They're not sure. NASA puts a lot of energy into making sure astronauts are healthy and they don't seem to have a plan for what to do if someone dies unexpectedly. URL_0 Probably they'd send the body down to burn up on rentry like they do with waste. | 3 |
8jb9bj | Technology | How do store shoplifting detectors know you are stealing an item that you haven't already paid for? I am referring to the devices you walk through upon leaving a store like the ones in Target, Walmart, Walgreens and the like. | Modern versions are often using an RFID chip under a sticker somewhere, a few years ago they would have been a small bump but now they're undetectable from a normal sticker unless you see the backside of it (usually metallic). | 3 |
ies9vp | Other | The difference between Athiest, Agnostic, and Secular | 1. no God 2. who knows if there's a God? 3. group, person, or organization operating independent of religion. | 3 |
63zfls | Culture | How "psychics", mediums and other frauds know specific personal information | What such people are is very good observers. Your body language tells them more than you can imagine, they see a ring or the tan line of a ring on your finger, they know you are married or maybe divorced lately? They listen to their surroundings. And when it comes to the typical conversations they use phrases that hit bulls eye with 75-90% of the people they talk to. In the case of your colleagues working in a cancer ward: Most people who work there care about others, have specific character traits...as you said superstitious bunch. The bread and butter of such fraudsters is to know their prey. | 35 |
gqlmoy | Other | What does "Kafkaesque" mean? | Kafkaesque is usually a reference to The Trial, which tells the story of a man being persecuted for unclear crimes by a very non-transparent, non-cooperative institution. Basically, saying that a process is Kafkaesque implies that it subjects the people to unfair rules for unclear reasons without any recourse. | 4 |
d00wyr | Culture | How did people learn foreign languages in the old time, when there were no dictionaries or teaching books? | \*Spanish speaker holds up an Apple to an English speaker\* "Manzana" \*Spanish speaker points to a tree\* "árbol" | 18 |
b6wmms | Technology | How do over the air transmissions (tv,radio) know how many are listening/watching to gauge the popularity/success of songs/programs? | Upvotes for both of you! That seems crazy to think if that wasn't tested properly they could be broadcasting to no one or tons of people. In addition it would be hard to quantify pricing structures for advertisment. Obviously the more listeners/watchers the more advertising is going to cost. Very interesting guys thanks! | 3 |
66465t | Mathematics | Why we learn such advanced math in school but most of us never do more math than counting as adults My kid asked why she has to learn how to find where parabolas cross the y-axis. My best answer was so she could teach the quadratic equation to her own kids one day. ._. As a secondary ELI5, why do schools not teach things like filing taxes which *everybody* has to do? **Edit** I talked to my wife last night, and she is a teacher. She suggested a few things, that she prefers being in elementary school because methodology change more easily--she has kids that learn better while they bounce, and she feels that as the kids get older the schools become more rigid. Further, kids heading into hands-on positions like your tradespeople, clerks, sales, don't need higher math like in high school. Even going to high school 80 years ago meant you were going to be something prestigious, like a lawyer, an engineer or something like that. I get that education, generally speaking, is great. Qualifications are getting more important as time goes on, too. I worked a camp job where they paid the 55 year old carpenters 4th year apprentice rate for not being ticketed and 28 year old me the full rate for having it. Those I ticketed guys knew SO MUCH MORE than me. That being said, I appreciate your comments and input but my opinion is still the same: math past grade 6 or so just isn't needed for the vast majority of jobs. | Math is an important skill to learn because of problem solving. You have to identify what information you have, what you need, and how you are going to get there. It is also great for physics, statistics, and business classes. Now I get why many people say taxes should be taught, but let us look at what taxes are. They are a set of instructions with **extremely basic** math instructions. Being able to read (English), and using those simple operations (elementary math) should be able to be accomplished by the time you are an average high school student. | 11 |
8vv1ug | Culture | How do character based written languages work? (Such as Japanese, Mandarin, etc) Is each character a word? Do multiple characters make one word? Does each line stroke related to a sound? When you learn to read, do you just have to memorize every single character there is, or is it like learning to read English where you learn the fundamentals and then can figure out how to create other characters? When you name a child, do you create whatever character you want? | Chinese characters (hànzi) represent words, or independent bits of meaning (termed morphemes). A lot of them correspond to English words, like *apple* or *car*, and morphemes: *un-*, *anti-*, *-ness*. Also grammatical markers which don’t really exist in English. To give an example *do you like apples?* could be represented as *you like apple & amp;amp;amp;amp;lt;question marker > *, you might notice the plurality is not actually marked (in Mandarin this is implicit). The characters graphically aren’t completely arbitrary. The simplest characters historically represented exactly what they looked like, and over time they became more abstract and kind of refined. Whether or not these simplest possible units can stand by themselves as characters, they can be used to represent more complicated things and concepts. The character for person or people is 人, or as a radical you might see this variation亻. By putting the person character next to another: 从, you get the character for *to follow*. That illustrates how characters are constructed and perhaps visualised for learning and such, but it doesn’t normally tell you the pronunciation and meaning on its own (only incidentally). It’s a little bit too abstract to rely on, so people normally learn the characters by rote, for the most part. It works similarly for Japanese kanji, but with some more historical context. Actually, many characters are similar or the same - lifted from the Chinese characters. Especially simple characters often have the same meaning. Sometimes they are used differently though, and very often represent different things altogether. A substantial minority are Japanese in origin as opposed to Chinese. A big thing to note for Japanese is that they don’t use kanji exclusively. The hiragana system maps syllables to symbols, so they can be used to write how something is pronounced for instance - or more generally alongside these kanji for grammatical inflections and young children’s books (who will not have a very large inventory of kanji yet). They have a third system called katakana but this is all but completely analagous to hiragana - with a different use case. Korean has a system of symbols similar to hiragana, or our alphabet which can reasonably be used to represent pretty much anything by pronunciation. You will sometimes see Chinese characters, but not in common usage. | 1 |
mdyqsi | Technology | How do they record Voiceovers for movies? Like how do they put the actors on mute, but still keep the sounds in the background? How do they manage to keep all the other sounds (special effects, music, etc.), while changing the actors' voices? | Im not an audio engineer myself, but my friend is and he’s done audio for some small movies and tv shows (although his primary work is music). Native voice audio for movies is often isolated with boom mics so the audio can easily be replaced with a voice over in the final mix. A lot of the background audio you hear is done by foley artists because isolated sounds give you the most control over the final product, especially since a lot of sounds wouldn’t be possible to record without foley (ie. Punching doesn’t make a big whoosh, nor does it make much of a sound in impact). | 4 |
9mccl8 | Economics | How come Americans can be fired (or layed off) for little reason and on short notice? | It’s a “right to work” state. People are tricked into thinking that this means you have the right to work for whoever you want. This means you can quit at anytime because no contracts and it also means they can fire you for no reason. People are stupid and let themselves get used. | 30 |
cc6e8b | Technology | How do places like Churches or MacDonald's avoid losing internet over illegal download copyright strikes from ISP's due to random folks who use their net? | Think more about schools. I work school IT. A thousand kids all accessing everything all over the place. Maybe filtered, but filters are far from perfect. Maybe logged but trawling through logs is hard work and more often than not ends up with "oh, it can from this chromebook alright, but the kid says he lost it days ago when someone took it from his locker"... so even identifying the device and user doesn't tell you who actually did the bad thing they're alleging. Generally, they don't even bother to try to shut us down - it's the people running \*services\* they are after, and you wouldn't be able to run a massive download service from our connection. The individual torrent, etc. users? Small fry and they don't care. I haven't had even a notification of such in over 15 years. I know it goes on, it flags on certain reports, and it's more often than not staff and guests with things running constantly in the background on their laptops (e.g. uTorrent). When you do get one - and I have had a couple in my working life - you literally just write back and say "We're a school, we operate public wifi, hundreds of devices and don't keep logs going back that far that we could reasonably analyse. Additionally, even if we identified the device or account in question, there's no way we can identify the actual person who sent the packets in question". That's the last you'll hear of it. If anything, the smokescreen of being a public wifi point means that you're more protected than if, say, you were doing it from your home account where only a few people live or could ever possibly have connected to it. But even at home, you just write back and say "Sorry, we don't keep logs, I have no idea who did that and no way to tell. I'll have a word with the family about this." EU law, especially, has pretty much established that even if it happened on your "connection", that's not identifying enough to prosecute, fine or pursue a single individual. An IP address isn't a person. You can't sue an IP address. You can't even sue the bill payer of an IP address at a certain time, they might be completely innocent (and a terms-and-conditions breach is civil so you can't really do much about it). Sure, if it happens enough, the ISP might well put extra monitoring on your connection, send you some warning letters and terminate the contract - that's about all they can do. And they really don't want to do that, so the evidence needs to be pretty hefty for them to even bother. Mainly because you'll just say "Okay, I'll just use another ISP". It's not like you have to take out a "pirate credit check" when you sign up to another ISP. Generally speaking, in schools and other places offering public wifi, things classed as "civil" infringements (copyright, private prosecutions, someone random "suing you" etc.) just fall by the wayside and nothing really happens (I might find the user that I suspect did it and give them a slap on the wrist, but that's about it). It's only "criminal" infringement (i.e. the police want to track an terrorist message, determine who hacked a website, etc. etc.) that actually gets any action whatsoever. Generally criminal infringements either demand the information from the ISP and then demand it from you (so the ISP really has no dealings with you in it, they are just required to comply), or they deal with the IT team direct in order to preserve evidence. Neither of those is likely to lose you your connection, unless the whole company is literally knowingly party to the same crime. There's a reason that you've probably never been to a cafe or a public airport and had all your website accesses replaced with a "This connection has been terminated because of repeated copyright infringement" notices. It just doesn't happen. | 2 |
mi8bs7 | Biology | why do headaches go away after you sleep? | i think it might be because if you’re headache is caused by eye strain from looking at a screen for too long or tension in your neck, sleeping will calm it down | 4 |
npbmms | Biology | How after thousands of years without shampoo and soap, we survived, and now we can't even think in a life without it? I just don't get it, I was trying to not use shampoo or use less of it, but when I train I really need it the same with soap, I don't understand how our ancestors clean themselves without chemicals that now we have, and I don't know if it's a thing like washing your teeth that actually increase your life expectations. | There's three benefits to hair care: cosmetic oil control, pest control, smell control. Speaking on America's history of shampooing: In the 1700's, lice was absolutely rampant, especially in the wigs men wore. The powder in wigs was partially supposed to act as insecticide but it rarely worked. Women's hair was also regularly lice infested. Women took care of their hair cosmetically by brushing their hair. This distributes the oil evenly from scalp to tip, and since women didn't cut their hair, there was plenty of hair to take the oil. They washed their hair perhaps once every other year. Hats were also huge! In the late 1800's and 1910's, with the advent of plumbing, white ladies would get their hair washed maybe every other week and set in style at a salon. Otherwise they would brush the oil out. Men's hair was short and oiled or waxed. This controlled the scent and made it harder for lice to get ahold of ladies. African ladies were sometimes forced, by law, to wrap or cover their hair. Sometimes they were also forced to relax their hair. Kinky hair is dryer than straight hair, so oil buildup is not as much of an issue. The harsh chemicals that relaxed hair would deal with bugs, but at this time fleas and lice were common issues for all poorer folks. Once World Wars happened, mass produced shampoos became the norm, since lice is a big deal with massive armies. After World Wars, soldiers took the habit home, plus home plumbing was more common so frequent hair washing could be done more often. | 4 |
88xxou | Chemistry | Why does club soda taste salty when bubbly and sweet when bubbles run out? | Carbonic acid. Club soda is water plus CO2 (carbon dioxide) bubbles. But flat club soda is not just water. Dissolved carbon dioxide actually changes the water. Water with dissolved CO2 is called carbonic acid and like it's name suggests, is mildly acidic which gives it a slightly bitter or vinegary flavor. Club soda also often has non-sugar sweeteners added for flavor that can remain. | 1 |
o2nb4p | Engineering | Why are diesel car engines so much louder than petrol, they sound like tractors? | 1 bar is atmospheric pressure. Remove the air from a steel oil drum - 1 bar is plenty enough to crush it. In petrol cars the explosion in the cylinder reaches about 20 bar under low load, and about 70 bar full load. In diesel engines the pressure explosion would be around 80 bar at light load, and potentially almost 200 bar at full load. This higher pressure makes the characteristic loud chugging sound. Also the fuel injectors which work at a crazy 2000 bar (!) make a characteristic clicking sound each time they inject fuel. This makes the characteristic click. Also tractor engines are generally diesel. Incidentally lots of small, compact European diesels aren't particularly loud nowadays since they are very effectively isolated and shielded. | 2 |
62km35 | Biology | Why can we not just plant a TON of trees to help reverse the effects of global warming? | I'm not sure why no one has touched on the obvious yet. Plants are part of the carbon cycle. CO2 gets pulled from the atmosphere and is used to create carbon chains like woody tissues, sugars, starches, etc. When they die, fire/decomposition releases the carbon back into the atmosphere as CO2. Planting trees is certainly a good way to pull excess CO2 out of the atmosphere, but there's a problem. We've been pulling carbon from deep underground (out of reach of the normal carbon cycle) for the last 100 years and releasing it into the atmosphere. We've effectively added carbon from an outside source to the system. For us to reach CO2 levels from 100 years ago, we would actually have to plant MORE trees than existed back then to suck up all the extra new carbon. | 27 |
913bav | Biology | Why even if you’re full are you still able to drink water and other liquids without it making you feel more full? I don’t know if there’s a scientific answer or not, but there will be times where I had just finished eating a whole meal and be super full, but if something like ice cream comes, I’ll still be able to eat it. Other things like soup have that affect as well. I thought maybe it had something if to do with the fact that they’re liquids but I wasn’t sure. | Fill a bucket with stones until it is full. The pour water into it. The water fills the empty space between the stones. Same thing happens with water. Also your stomach can stretch a fair amount. | 1 |
ltbuyv | Physics | how do UV shielding windows work? | Normal glass (used in windows and such) is not transparent to UV light. It mostly absorbs the wavelength,(it reflects some), the same way say asphalt absorbs almost all wavelength or your blue T-shirt absorbing all wavelength but blue. Absorbed photons transfer energy to the material (usually electrons) and turns into heat. | 1 |
g3rmdn | Technology | How can robots not beat captchas when some are as simple as clicking a button? | The button clicking captcha is deceptively complex. It's really a masterpiece of design to be so simple for a human and yet still be effective. With the button clicking captcha you've already 90% passed the test before you ever see the button. They've looked at the various metadata that your computer sends, like what your browser is, and seen that it matches patterns associated with real people. They've seen that this is the first request from your IP address, or perhaps they check that you're logging in from an IP address that's already associated with the account you're logging into. By the time you see the button they're already pretty sure you're a human. Then you click the button, but it's not just a click. They watch your mouse motion. They check to see if the mouse jumped straight to the button and issued a click event. They check to see if the mouse moved in a perfectly straight line, or with other improbable uniformity. Ultimately the button clicking itself isn't that hard to design a robot to beat, but it would take some time. Once you perfect the button clicking robot and start using it you start failing all the checks that led to you getting the button clicking problem in the first place. Perhaps you make a simplified web browser that doesn't register properly as being Chrome/Firefox/IE/whatever. Perhaps you make too many requests in a short period. Perhaps you try too many times to log into accounts that don't actually exist. You quickly wind up flagged as probably a bot, so you get sent to the "hard" captcha like image labeling. Image recognition is one of those fun problems where the software to do it is increasingly well understood (it's an active area of research, but computers have been out-performing humans for several years now). The challenge in making an image labeling program is that you need a lot of human-labeled data to train it off of. It's costly and time-consuming to gather that data (which is the other service that companies like recaptcha offer—they're using your clicks to help big companies train machine learning algorithms for tasks like self driving cars). In the end the process for developing a bot to defeat captchas is straightforward enough, but the effort it would take to do so is greater than the effort it would take to just hire a bunch of people to solve the captchas for you. That's the threshold for "good enough" for a captcha. | 2 |
jbosax | Technology | Why are beakers made of glass? Is there a special reason for why lab containers like beakers or test tubes are made of glass besides the fact that its see through? | Glass, particularly borosilicate lab glass, is highly resistant to chemicals. It's also temperature insensitive, so it doesn't crack when heated or cooled. | 4 |
69k3zl | Technology | why does switching website players from flash to HTML5 take long time? iirc twitch and crunchyroll are in the middle of this process isnt it basically just uninstalling/reinstalling plus writing some code changes? they dont need to remake their websites or anything right? | A flash site is actually a large amount of custom-written software specifically designed to work with the flash system. It has to be completely rewritten to work with HTML5 instead; the two systems are not very similar. Consider switching a Shakespeare play from English to Chinese. You need to redo every word, and even though software can help you with parts, ultimately you will be completing the whole job, meticulously, by hand. | 2 |
5mjbbf | Technology | How do we connect a prosthetic limb so that it can "feel"? And on top of that, how can we connect the brain to the limb allowing for our brain to control said limb? | We don't need to. If the brain interprets that limb as our own, it will go on to fabricate sensations based on other sensory input. [Watch this]( URL_0 ). > And on top of that, how can we connect the brain to the limb allowing for our brain to control said limb? Cybernetics. Stick wires into the brain. Learn the rest through practice. | 1 |
bwnjps | Biology | nightmares? Why would your brain scare you? | It doesn't know it's scaring you. The brain has a fluke whereby when it's processing data and sorting it, it actually has to access it to see what it is. This makes your conscious self experience the thoughts. It's like if you were a library assistant to audio books without any titles. Well, the Librarian would have to listen to every one to figure it out, and you have to manage to do your job through every dumb noise. | 12 |
7wylu9 | Biology | doctors of reddit, what is the difference between intrvenous, intra dermal, and intra muscular injections ? | They’re all different routes of administration. Intravenous is into a vein, Intradermal is into the dermis, and intramuscular is into the muscle. Many different factors go into deciding what route to administer medications. | 1 |
8mnqkv | Biology | How does an ant not die when flicked full force by a human finger? I did search for ants on here and saw all the explanations about them not taking damage when falling... but how does an ant die when flicked with full force? It seems like it would be akin to a wrecking ball vs. a car. Is it the same reasoning as the falling explanation? | Because they are light. So they are easily moved instead of deformed. If you flick against the ground they will get squeezed and die, but if you just flick them in the air, most of your force is directly translated into movement, which is not dangerous. | 13 |
l6yx7j | Economics | Why wouldn’t raising the minimum wage result in a proportional increase in consumer goods pricing (nullifying the wage increase)? | Because labor costs cannot be completely passed off to consumers in a functioning market. The milk company can't just charge whatever it wants. Other companies will cut costs to undercut it if it just raises prices. Likewise, even in non-competitive markets, willingness to pay for milk and all other goods doesn't just increase on a 1:1 basis with your income. Whether you make $7.25 an hour, $15 an hour, or $500 an hour you probably still wouldn't be willing to pay $10+ for a gallon of milk (unless you live in Hawaii). Willingness to pay for most goods does increase with income, but not anywhere close to a 1:1 ratio with income. | 2 |
60nomu | Biology | When we get sick, why does our throat randomly get sore overnight? | Normally your body does a good job of getting rid of your everyday bacterial infections. You might have several colonies of harmful bacteria thriving inside your body but you won't even notice. However, when your immunity system is busy dealing with a widespread viral outbreak, like the flu, bacteria might take advantage. To deal with throat infection I recommend mouthwash. Once you feel your throat getting dry/sore, that's the bacteria settling in. Apply mouthwash several times to get rid of them. It will be over before it becomes a real nuisance. | 1 |
htvhvs | Biology | Why do humans like music? | We enjoy music because it makes us feel good. Using MRI scans (magnetic resonance imaging) scientists showed that people listening to pleasurable music had activated areas in the brain called the limbic and paralimbic areas, which are connected to euphoric reward responses, like those we experience from good sex, good food and addictive drugs like heroin. | 4 |
8ldbwi | Repost | ; If the court orders your to pay a ludicrous sum ($37m) that you blatantly cant afford... how do you pay it? | First of all, if there's a judgment against you in the US, the court doesn't care if you can pay it. You either pay, or you don't pay. Depending on why there's a judgment, you might be able to declare bankruptcy and get rid of it. Secondly, if you really can't pay, then you can still negotiate with the plaintiff. "You know I can't pay you $37m. But, how about this: I pay you $10 a week for the next 20 years. If you don't accept that, then you're going to have to execute on the judgment, which will cost you time and money. And, if you try that, then I'm just going to declare bankruptcy." Third, the plaintiff can execute the judgment. He/she can order the bank to give him the money in your account, get the sheriff out to your house to grab your TV and your car, garnish your wages, etc.... (The exact remedies depend on what state you're in and how you got the money. Garnishment, for example, is typically limited to a percentage of your income. Social Security benefits are immune, etc....) | 24 |
9obvtq | Culture | Is Islam really as violent and mysogynic as people say? | Islam is not really as violent as portrayed, as 99% of muslims want to live their lives in peace and wealth, generally minding their own business. There are a few dozen muslim countries in the world, but all violence we hear of occurs in a handful of those countries. However, I dare claim that most Islamic countries are generally less stable than their western counterparts and might have higher murder/violence rates etc, but it's not that every arab dude is heading out with his sword on the daily, for others to behead. The conflict zones in the Jemen, Syria, Iraq, Afghanistan are definitely among the most violent locations on the face of Earth, but then again, I'd say Istanbul is about as safe as Los Angeles. & #x200B; Let me also add that in most Islamic countries, there is a lot of socioeconomic tension, with a large margin of the population being extremely poor and thus desperate, so that a clueless tourist stepping into the wrong district of Cairo at the worst time may lead to awkward situations, especially if he has a wallet full of dollars. But that applies to Rio de Janeiro as well, so it's not related to Islam. & #x200B; Also, there are anti-american and anti-european sentiments throughout the Islamic world, especially in the levant as we fucked them over politically for decades, one example being the Israel/Palestine conflict that partly stems from British/French imperialism. & #x200B; & #x200B; Islam is quite mysogynistic, as women have fewer/no rights by law, but that differs from country to country. That applies to the arab world, but not to Turkey, which is pretty progressive in comparison and countries in Central Asia might be a bit more progressive than arab countries, but I don't know much about those. & #x200B; & #x200B; | 7 |
6x9p6b | Biology | What do people really mean when they say things like "your metabolism slows down after 30"? I realized that I take this saying for granted. Is there actually any merit behind it? I am starting to think that people just become more sedentary after 30, and maybe this is the reason so many people tend to gain weight (aka 'a slowing metabolism') as they approach middle age. | You start to lose muscle around that time and less muscle means you need less to eat less or get larger. | 2 |
c4cjoj | Biology | How can one feel someone staring at them? | Its not. Numerous studies have been done on this and its shown people are about as accurate as flipping a coin. You just forget the times you were wrong because it doesn't matter. | 2 |
btk5in | Physics | Why is it portrayed in movies that if you get bigger to smaller people you look like you're moving slowly | When we walk forward, we are actually falling over forwards, only to stop ourselves with a foot. Gravity is the same value even at the larger scales, and so their limbs would fall at the same rate, but since they are so big there is much more distance for the limbs to travel before they hit the ground. With regards to the booming voice, their vocal chords and mouths now have lower resonant frequencies. It's totally legit that they might speak louder and deeper. | 1 |
6wbi5v | Repost | Why do most men go bald, in spite of all the testosterone? I'm 25, I have a full beard, I have new hair coming out on my back and shoulders but the hair on top of my head have started falling. What's up with that? Are the rules different for that part of the body? EDIT: What the hell? Ads about hair products started showing on reddit. Ads do get smarter. | It's because of a genetic mutation that causes a specific area of the scalps follicles to be sensitive to DHT - a preprogrammed pattern. It takes a long time for the follicles to respond to the onset of it but eventually it gets ya. I am bald on top and it actually initially started with me when I was 17 at the very edges of my forehead! So minor it was back then, but 18 rolled by and it wasn't too bad, then 19 it got slightly worse, creating the more defined M shape (no spam at the back first, thankfully), then 20 it progressed quite a lot on the tops of the left and right of the forehead and by 21 it got so bad at the left and right of my forehead that I started shaving my head completely. Realistically I could have just had short hair but meh. Through 21 to 28 it thinned out on top completely so I now have the definitive horseshoe shape if I don't cut my hair, but I shave my head completely anyway. If I run my hand across my head through the middle there is still a quite a few bristles but no where near enough to grow it - I am fortunate my hair is a mousy blonde colour so it doesn't show as much. Fortunately I don't look too bad bald/shaved and kind of suit it. Some people are very unfortunate and do not. So yeah, testosterone encourages hair growth, but a messed up genetic mutation is why a predetermined pattern of weakened hair, sensitive to DHT is why we lose it. Like all of these things, just like other genetic inheritance of, say, diseases, the onset is unknown but expresses itself within a certain time frame - this is why some of us get hair loss at varying times, some very late, some super early (like me). For example; my Dad is bald and his Mother, who he heavily takes after, her father was bald. I take heavily after my Dad but he had decent hair till his mid 20s, I didn't. It was a lot more pronounced on my forehead earlier on than on my Father. My Grandfather, who I don't take after much, is bald but that didn't affect him till his 50s. So the genes are all there. My Brother however takes heavily after my Mother, whose father isn't bald nor is my Mother's father (as far as I am aware). So while my Brother is whining about his receding hairline at the corners, left and right of his forehead, and has been moaning about it for years, his hair receding is so minor it seems to me, ridiculous. My brother is 9 months younger than me and he has almost all of his hair. He is at the stage I was at 19/20! (We are currently both 28, but I will be 29 in February). Blah, rambles. My apologies. A lot of shit will happen if you cherish your locks... Or not. Look at your family history and try not to worry too much. There are ways of slowing hair loss, even if it is genetic Male Pattern Baldness (MPB). However do not go spending fortunes on trying to cure the inevitable. There are cost effective solutions that can slow the process but it isn't a guarantee for everyone. Or, you may be lucky and it may not progress heavily till you are older. You may experience a roller-coaster of emotions or you may be more chilled about hair loss like I was. There will be moments in your life where you get pangs and thoughts or wishes of having hair or doing something about (transplants, research, etc) but the best way to be is to be accepting of yourself and not trying to please everyone else. My brother once told me that the new people you meet will not find you ugly or weird looking because they have only ever seen you with your head shaved... So yeah that helped me when I had my doubts about going out. If you are worried and it appears to be progressive, instead of clinging on to hair like it is all there is to life, experiment with shorter hair styles gradually over the years until eventually cutting it to 0.5mm with a trimmer - this means it is a less drastic or shocking change to people you are around rather than going from longish hair to slap head, because stark differences, whether it be hair or anything else is always going to draw attention. You don't have to go cue-ball style. In fact, I never even started using a razor on my head until a couple of months ago! You really don't need to use a razor. Short and tidy 0.5mm hair will show a faint outline of where your hairline is, but because it's very short it looks good, not old man style. Embrace le bald when the time comes, it is not as bad as you think. All the best dude. Remember, don't worry! (งツ)ว (Edit: added info, corrected mistakes - forgive me, I was having a hypo :D) | 24 |
6acqky | Technology | How does international phone calls have almost no delays(Zero ping) but internet voice chat lags a lot, and wouldn't even connect if the distance was big between the called and receiver. | Fundamentally there's not a lot of difference between the two. With a long distance call, your voice is fed into a computer are the exchange which digitizes it and breaks it up into packets (which is basically the same thing skype voice does). These packets are sent as data via a fibre optic network to the other end of your call. Services like skype differ only in that they use the regular old internet for transport and long distance calls use a purpose built network. On some level the internet adds extra layers of protocols that increase overheads and make it slightly less efficient but that probably isn't the main reason. The deeper answer is engineering. Long distance calls certainly aren't zero ping, but the data networks they use are designed, purpose built and optimised for low latency when used with a low data rate, intermittent stream of packets. The internet that acts as the data network for services like skype on the other had is designed and optimised for general purpose traffic, plus it tends to offer various connection speed options to every customer on the way through, all of which might not suit the kind of data that your skype call generates. | 2 |
6udxmd | Biology | When you get a massage, the masseuse seems to push the knots to specific spots to make them disappear. Where do they go? | There's a ton of misinformation on this post. Sorry for that but really we don't know what causes them or why they go away. The current theory is that the motor neuron that controls the muscular contraction is malfunctioning and secreting too much acetylcholine, which is the chemical that allows a muscle to contract. So the muscle is just in a steadily contracted form. A mild contracture. Manual therapies are meant to "reset" this malfunction by sort of tricking the neurons into relaxing. The neuron is accidentally sending a signal to your brain that says that this is the most relaxed state for this muscle. What we do is gently force that muscle into a relaxed position. Edit: i do hope more people see this. Some of the top comments on here say that there's no scientific evidence that massage does anything. Well yeah uh. There's no scientific evidence of anything if you don't look it up. Massage is proven to stimulate RNA synthesis to the massaged region. It helps rebuild your tissue in the aid of recovery. URL_0 | 20 |