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41sfjj | Why does health care in the United States cost more than twice as much as other similar, developed nations? | There's several aspects to it. First, Americans consume a lot of care--people are too often on prescription medication, for example, and many people get expensive tests when the circumstances do not warrant it. One way that countries with centralized healthcare monopolies keep costs low is that they restrict access to healthcare by setting limits on coverage to what the public insurer feels is appropriate.
Another factor is that not enough of that care is preventive. Many (but not all) forms of preventive care are good investments that are cheaper than treatment of the ailments they prevent. This also brings in public health factors not strictly related to health care, such as exercise and diet.
Lastly, hospitals have to cope with a very high percentage of people who do not pay their bills, either because they do not have insurance or because they do not pay the remainder that is not covered. Because whether any particular bill will be paid is a hit-and-miss process, the hospitals inflate the cost of care in billing, hoping that those who do pay will make up for those who don't. Aside from a basic unfairness, there are many additional administrative costs. Any plan that leads to better general coverage will help combat this factor. | af77de15-7bab-4cfe-b41f-55d9f5c34fd1 |
8d7e3m | How Do The Mega Rich Like Bill Gates Have Free Access To Their Own Money If It's Mostly In Investments And Stocks? | Having most of your money in investments and stocks is not the same as having all of your money in it. Gates is worth 91 billion dollars, so even if he had only 5% of his money as cash on hand he would still have 4.5 billion dollars available to him for purchases. | e370b6a3-ed9a-449e-bc46-b98d0cea8df9 |
2zwhv7 | When we are tired, does eating makes us less tired because of the energy provided in food, or the other way round because of the energy needed to digest the food? | Eating and digesting a large meal draws a lot of blood around the stomach and intestines. This can make you sleepy because less blood is perfusing the lungs (picking up oxygen) and taking that oxygen to the brain and other tissues.
Eating *in general* provides you with energy to perform required bodily functions necessary for life.
Tryptophan and melatonin, which were mentioned in another post, are never consumed via food in large enough quantities (even at thanksgiving) to make you sleepy. It's digesting the large turkey dinner that makes you sleepy. A melatonin pill will make you sleepy, but that is unrelated to food digestion. | e5998692-d2cc-4c67-8ab2-25cffe65c78f |
6zfm22 | How did they measure the height of Mt. Everest? | With great difficulty over the between part of a century.
[The Great Trigonometrical Survey of India](_URL_0_) started from the ocean in 1802, and 100 feet at a time, took measurements and did a bunch of math, and worked there way across the sub-continent to the Himalayas, completing in 1871.
It was a great scientific achievement, lead during some of its more important years by George Everest, who received a knighthood for his efforts.
The basic technique is fairly simple. You start with two sticks at sea level, a decent distance apart, and measure their exact longitude and latitude. Then you put a third stick some distance away and inland, making a triangle. Based on the distance between the first two sticks and the angles they form with the third stick, you can compute the thrid stick's exact position and elevation.
Once all that is done, you repeat, planting a stick further inland and drawing a new triangle. The Great Survey did this with better instruments, better technique, and to a greatly scale than had ever been done before. | 7c093a30-59ed-4df9-82a2-b04979b19d01 |
325iym | In MLB baseball they have technology to show if the ball was inside or outside the strike zone, so why do they still have home plate umpires making subjective calls? | Tradition, and what people like. A ref's judgment is part of the game. Consulting a replay or computer to see if a ball was in or out of the strike zone every time there's a dispute changes the flow of the game. | afed5b13-6dc5-4adc-9d69-94cb99970386 |
1btf6s | How do gas pumps know when my gas tank is full? | > This mechanism has been around for a long time, so it is safe to say there is not a miniature camera inside the nozzle hooked to a microprocessor. It's purely mechanical -- and ingenious.
Near the tip of the nozzle is a small hole, and a small pipe leads back from the hole into the handle. Suction is applied to this pipe using a venturi. When the tank is not full, air is being drawn through the hole by the vacuum, and the air flows easily. When gasoline in the tank rises high enough to block the hole, a mechanical linkage in the handle senses the change in suction and flips the nozzle off.
Here's a way to think about it -- you've got a small pipe with suction being applied at one end and air flowing through the pipe easily. If you stick the free end of the pipe in a glass of water, much more suction is needed, so a vacuum develops in the middle of the pipe. That vacuum can be used to flip a lever that cuts off the nozzle.
The next time you fill up your tank, look for this hole either on the inside or the outside of the tip.
_URL_0_ | 147ff625-9a14-44d4-b12e-a16b9b58da7e |
2yo3o9 | Why are most small cars front-wheel drive in favor of rear-wheel? | Additionally, building a rear-wheel drive vehicle is actually far more complex that building a front-wheel drive vehicle. This is for a number of reasons that would take a while to explain, but essentially involve torque, driveshafts, and space to accommodate the driveshaft | 72540869-9357-4497-838e-9615ae5257fa |
1mk8f4 | Important Keynesian Economic principles | He believed that there is a basic relationship between total aggregate consumer spending and the rate of employment; that is when the consumers spend more, there's more employment, and when the consumers save more, there's more unemployment. Many of his policy suggestions stem from this. Whether or not there is a relationship between aggregate spending and employment is contentious and often debated.
Keynesian economics is the most popular economic school of thought at the moment and, for the most part, dominates politics. It is also the most common economic school taught at universities. The governments inflationary policies, stimulus, bailouts, and other policies, are all based on Keynesianism. In my personal opinion, it has been tried time and time again, and has shown to be a failure. | c864ca31-301c-4ea2-bcd5-2f7d60d9beda |
1hxp65 | How is the Gitmo force feeding procedure done on Mos Def different from the feeding tube procedure done in hospitals? | Presumably the people being force-fed in hospitals WANT to be force-fed. | ae6498bd-99b1-4a18-a006-aed9f31e1c9f |
1nsewq | Why are some morbidly obese people given mobility scooters to get around? Doesn't it make the problem worse? | Because with obesity you can reach a point of no return very quickly. For instance, peripheral edema and diabetes can severely impair circulation, causing neuropathy and skin problems, damage that may never be healed no matter how much weight is lost. Joints wear down very quickly, impairing a person's ability. A severely obese person is going to likely have sclerotic arteries, and be chronically short of breath.
A person big and "crippled" enough to use a mobility scooter will need to diet and exercise with the help and supervision of a medical professional. It's much more expensive and has many more issues involved that the average Joe wanting to lose that extra twenty. A morbidly obese person cannot simply go on a jog (as another poster said), they may actually die attempting it.
I'm not saying that a person in that situation cannot improve themselves, but it is much more difficult, involved, and costly than the average weight loss scenario. | 049139d7-74df-44cf-9ca5-8e6968d6a0a6 |
3ghij8 | What is the difference between regular ice cream and soft serve ice cream? | The amount of air in it. To make it "soft serve" there is more air injected by the machine. It's also mixed continuously, to keep the air from separating. Yummy. | 94c11e78-cc12-49de-acee-bd7e686f3bc3 |
64tpbf | what is the best way to go to sleep earlier? | The keys to reduce stimuli that has the potential to keep you awake an hour or two before bedtime. This includes electronic devices or anything that emits any kind of blue light. Once you pick a bedtime and a wake-up time, make yourself stick to it. It will take a couple weeks to get your body adjusted but it's very doable. | 5174399d-9ba1-4bd6-b1c6-62aef399f4a1 |
3oo2hi | Are those almost perfectly curved land forms near Poland and Kaliningrad man made? | They are natural. It's called "spit" according to wikipedia, this image from wiki explains clearly how it forms because of sand carried by water currents paralel to the land: _URL_0_
Mildly interesting fact - Poland is considering making a canal through that patch, because right now ships from Elbląg have to go thorugh Russian-owned strait near Kaliningrad,and Russians sometimes make problems for Polish ships (political issues). | 2f6ead2b-889a-40d4-8d47-a04ea1799244 |
1a0zk5 | Why do we get cold chills when we're sick? | When we get sick, our body begins to produce various chemicals (e.g. cytokines) that travel in the blood to the part of the brain that controls our temperature regulation (in a part of the brain called the preoptic area of the anterior hypothalamus). These chemicals change the set temperature that we normally run on and make it increase, causing a fever. (The fever, as TheDrunkPillow alludes, is to make it harder for the bacteria, virus, or parasites to move around and survive in your body.)
So - this is where it seems backwards - we now have a bunch of chemicals rushing around your blood stream, messing with the part of your brain that usually keeps you at a toasty 98.6F; you are now running a fever of 101F. Strangely you begin to feel cold and shake, when clearly you are not cold at all. This is due to a couple things: one being the altered sense of temperature that comes with messing with your internal temperature. Your body is attempting to get you to run a higher temp, and you will feel cold and begin to shiver until you get your temperature to that new, higher number. (The shivering helps your muscles make heat, aiding in increasing your overall body temperature.)
The second, and more important of the two, involves the fact that once the brain is told to raise your temperature, certain brain cells begin to work on changing your blood flow to your arms, legs, and skin. The blood gets sent to your internal organs helping raise your temperature even more. This is, likely, the main contributor to you feeling cold when you're sick and running a fever.
I hope that helps! Can cite sources if you need it. | 1f3b8720-6889-477d-93d3-c74b8ae7aa7e |
4o89mx | LinkedIn (LNKD) is trading at $191.41 right now, but Microsoft has agreed to buy them for $196 a share in an all-cash deal. Why are they not trading at around $196? | The stock price is adjusted for risk. The sale will not go through for some time, so there is some risk attributed to this and time-value of money.
This means it should be worth a little less than $196. As we get closer to the sell date, assuming the sale goes through as planned, the stock price should rise to near or at the sale price of $196. | ece10810-1251-4e8b-a1bc-bdda3f9357b3 |
5mbtd1 | How have we not found a way to harness lightning | The average American household (with its 2.59 inhabitants) consumes 41 billion (4.14*10^10) joules each year. If your house ran on lightning alone, it would have to be struck more than 40 times per year! There are 114 million (1.14*10^8) households in America. Multiply these two numbers, and you have 4.72*10^18 joules of energy per year. Every lightning bolt on Earth in one year, captured perfectly with no loss of energy, would contain about 4*10^17 joules of energy. Thus, all the lightning in the entire world could only power 8% of US households. At best.
Could this few percent be realistically used? To answer this, we need to look at the practicalities of capturing and using the energy. First, we can imagine that the United States would probably have to restrict itself to domestic lightning sources. This limits us to about 30 million bolts per year. Now we can only power about 0.6% of our households.
How about the electrical engineering required to transform a lightning flash into a spark in a wall outlet? The greatest challenge here is that all of the lightning's energy is transferred in tiny fractions of a second. This means we must have an incredibly large battery (or capacitor) that can charge up instantly when the lightning strikes, then slowly and steadily let out the bottled up power when asked. Devices with these capabilities are both difficult to produce and very inefficient. Physics tells us that we cannot store and retrieve this energy with 100% efficiency. In fact, we lose the majority of the energy we are converting in nearly every process. Compounding the limited total energy and the difficulty and loss in accessing it, we can barely create a tiny fraction of a percent of the power that we use every day from atmospheric lightning.
Sadly, it is completely, utterly unfeasible to use lightning for electricity. But cheer up, it is still beautiful to watch.
[Source](_URL_0_) | 0d67e1a7-8f4c-4d34-95fe-6c2c3209795d |
2hs0df | What is happening when we learn to like something like coffee? | The answer to this actually applies to a lot of things in life.
The thing is by repeating something continuously it becomes part of our routine and we become accustomed to it. As so, it doesn't feel out of place anymore even if it isn't the most exciting thing.
I also said that this applies to other things in life, and here something from mine. Last year I finished highschool and the university in which i started going is in another town. The bus ride was about forty minutes and as many people in my town we made that trip every day. It was really tedious to me at first and i remember complaining about it often. After a while it just stopped feeling weird and the busses were suddenly okay, the road was cool, the people weren't sweaty , etc... I guess my brain just started ignoring the little details that would bother me at first.
This also goes both ways. In the same breath, going to university was a great experience, and i couldn't stop talking about everything. All seemed so special. Then as times passed and all those awesome things became part of my routine it didn't seem that exciting anymore. Not that things got worse but it didn't feel like something else anymore, ot was part of the daily routine. | 2c4596e0-7dbb-40a4-88e4-3fd969e0d386 |
7wxi2w | If hypertension can cause erectile dysfunction, will lowering blood pressure to normal levels reverse erectile dysfunction? | Well one of the main side effects for Viagra is a drop in blood pressure. In fact viagra was originally researched as a hypertension drug. It was only when the erectile dysfunction side effect was discovered that Pfizer realized they had struck a gold mine. | 614e2139-8d77-4e73-95b7-df73e86c9c1c |
2e1bek | Why don't people questioned by ISIS pretend to be Sunni? | Sometimes they can determine likely sect-membership by names and/or addresses/neighborhoods/towns and/or even jobs. But, with more certainty, they ask detailed and possibly obscure questions about religious practices that vary between the sects. Most people raised as Shiites won't know some details about Sunni religious practices. | 360b0228-b934-44bc-b072-b7bc6d2ac07e |
5kpyyy | Why can't car tires be solid rubber? | The "springiness" of an air filled tire helps delivery a smoother ride, and the ability to deal with minor imperfections in a road surface. A solid (using readily available rubber technology) wouldn't have the same ability to deform itself, so every little bump or object on the road would be transmitted to the body of the vehicle. Not only would this make for an uncomfortable ride, it would also affect steering, road contact therefor safety, and put extra stress on the remainder of the vehicle (through shock damage)
There are, and have been, airless tires developed. But, they are not quite ready for everyday use, either due to price or perfromance | 49ce91fb-7baf-41ea-845c-d6dd4cc7b192 |
jkzoq | What my download, upload, and ping numbers mean for my internet connection (picture included) | Simple, lets go off the "Internet works like mail" analogy. You love sending packages filled with jelly bean to your friends. However, depending on who you ask to deliver for them, they might take longer to get to your friend. Some messengers won't take big boxes, some love to bring your trucks of boxes but will hesitate at sending boxes to your friends.
Now this box is metaphorically a lot of things, so to tie in -
Ping - How long the box (or any internet message) takes to get there. If you are playing games, you don't want the Nuke of Death to activate five seconds after you click, you want it NOW. This is why you need a low ping, specially in shooting games. Because seriously, you totally shot him before he hid behind the wall.
Download speed - How many boxes they can bring you over a period of time. Rather simple.
Upload Speed - How many boxes you can send over a period of time. Because some messengers use planes, and some use garbage chutes, this may sometimes be slower. With a garbage chute bring you your mail boxes will come quickly, but do you think you'll be able to send much?
TL:DR; Ping is how long a message comes and goes from your computer to another server, download speed is how fast you download, ditto for upload speed.
Edit: Hurr durr, answer the question: A ping below 200 is expected, below 80 (preferably 60) if you plan on gaming with time sensitive games like shooters. Your down/up speeds are average for the United States, but just don't look around. The kids on the other side of the playground are using teleporters. (50Mb/s and much higher) | d0bfb640-ad06-4b31-9609-f58f7ab4021e |
2b9ekk | What is the reason for the movie clapper, i understand it might help with editing but why the clap? | It has already been answered, but I will add some more detail.
A camera records the visuals, an microphone records the audio, obviously. The problem is, that unlike with consumer cameras, the audio isn't recorded to the same file as the video. So, you are left with a very high quality audio track, and a separate video track. The board, which also has information about each scene, is what joins together the two tracks. On set, the camera man will film the board, and the audio people will record the sound of the board. Now, when the two tracks are brought into the editing suite, they can sync the audio by going frame by frame and finding the point in which the board closes. Then, on that frame they will line it up with the peak in the sound waves. This is a lot easier than someone figuring out how to sync voices up. | 0d79dfb5-d3d5-4eaa-a2f9-077bafe83500 |
3ofgld | At what point is bad grammar considered a new language? | The general rule of thumb is that if people can understand each other, it's a dialect, and if they can't it's a language. I think bad spelling and grammar vs actual rules is just a question of if people are consistent. If you accidentally wrote "teh" instead of "the", that's bad grammar. If you consistently write "ain't" along with all the people in your community, it's part of your dialect. | 52cc496d-9a2d-4041-8423-9713768d674b |
76k8n8 | how do sports announcers know how to pronounce all the players' names? Whose job is it to tell them? | One of my friends is a sports caster out in Nebraska and I asked him the same thing years ago(he casts football games). He said that he spends an average of 20-30 hours studying for every game he calls, from memorizing the pronunciations of players names, the number they wear, stats they are known for as well as interviewing players to get little known facts about their lives. In addition to this, the casters have producers who are constantly combing though a database about these players and feeding this information to that caster though an ear piece. They can give them up to date facts about the players, as well as what was seen in different shots and different camera angels. He let me see the inside camera once from their booth and hear the audio feed from the producers(This is what they use to help themselves get better and even have a breakdown session after each game). It may seem like a great gig from the outside, about the amount of work and stress that actually goes into calling a game well is incredible. Much respect. | ec313182-c5a2-4d82-8233-f74f89f414af |
661ca3 | Why does time slow down in near death experiences? | This is a good starting point.
_URL_0_
Short version, the material near the core of your brain controls sensory perception, reflexes, immediate survival based decision making.
Material further out controls emotions, higher level thinking, etc.
In a life or death situation, blood and vital fluid concentrates near the center. Think of it like diverting power.
The result can seem like heightened perception, better focus, minimized distractions. | 2e998c90-e83c-4c8b-9276-fa0e10db11d8 |
8weof4 | Structurally, how is a GPU different from a CPU? | Vast oversimplification, but you can think of a GPU like having thousands of weak cores while a CPU has a few powerful cores.
When you're rasterizing graphics, each pixel is independent of each other--a GPU can calculate thousands of pixels at the same time.
But not all processes are this stateless. Oftentimes you can't proceed without knowing a previous step. In fact, most tasks are like this, and that's why CPUs are still more important. Only some tasks are suited for mass parallelization. | 05177748-44f5-42fa-81d0-d6b01366488c |
1mpm2x | How can the probabilities of all possible outcomes of an event not sum up to one? In other words, how can there exist a process for which unitarity doesn't apply? | > However, the physicists who came up with the model postulated that locality and unitarity do not hold true at the quantum level.
No, that's not correct. They have a different mathematical formulation where unitarity and locality emerges from first principles. The end result is very much unitary | d0745a67-7ca5-42d6-8dd1-18605e2991bc |
1wma0g | Why (near) perpetual motion car is not possible. | Solar power is the only promising possibility, as you're taking "free" energy from the sun and converting it to useable power. But isn't very efficient yet, and the needed components add noticeable weight. Thus the charging rate of a car completely covered in solar panels still isn't enough to power the motors to move the car forward. It can be a net positive to add to other systems, but it ends up being a very small gain.
Alternators need rotation to make power - where does that rotation come from? If it's tied to the engine or wheels, then you're still gonna make less energy than the engines are consuming, plus adding drag to the engine, meaning it needs more power to move the car forward than it would without the alternators, so you end up with a net loss.
Same with wind power - the wind pushes on the blades to turn them, but that also pushes the entire car backwards, against the direction you want to go. The engine needs more energy to overcome this, giving a net loss.
TL;DR: Theory is nice, but in the real world efficiency, friction losses and heat losses mean you get less energy out in useable power than you put in to make the system work. | 1c758a1a-3289-4647-9262-902d534d5bfb |
5osc8r | Why, as an 18 yo in California, my parents need to sign a waiver allowing me to sign myself out of school or sign anything for myself. | because that's the contract between your school and your parents and you as a minor.
as an 18yo, you can drop out of school, if you don't like that. | 11ba5ad8-fbb9-4b82-8916-9c9b10e75fcb |
79la6p | what’s the difference between emigrate, immigrate, and migrate? | Migrate is general and just suggests moving from one region to another. Emigrate is to move your residence out of your country, and immigrate means to move your residence *into* a new country. So, if I move from Germany to France, I have emigrated from Germany, immigrated to France, and I have migrated from one country to another. | 9d1a44fe-3191-46e9-bd39-b891ca30b22b |
ncknc | Time flow in singularity. | It definitely isn't infinite mass. It's infinite density, which is a critical difference.
The rest I'll leave to others who are more educated to comment. | cf472e03-e342-4f42-bc33-e4ace6cc81a6 |
1kly7y | How do north koreans leave their country? | The show Vice did a documentary following a North Korean refugee who wanted to escape North Korea. The first step was illegally crossing the border into China and meeting with someone who specializes in getting North Koreans out (kind of like a *coyote* who specializes in smuggling Mexicans into the U.S.). These men were paid by a South Korean preacher who devotes his time to getting people out of North Korea. Next, the defectors took a several-hour-long journey across China into Laos. They are still not quite safe because the communist government of Laos does not recognize the refugee status of North Koreans and so would deport them back to their native country. After hiding out for the day, at night the defector and her party crossed the Mekong river into Thailand, which does recognize North Korean defectors as refugees and allows them safe passage to South Korea. Once in South Korea, the defectors go to a processing center that the SK government has established to teach defectors the basic skills needed to live in modern society. The documentary mentioned that for young North Korean women, the journey has an added risk of the Chinese middlemen selling them into sexual slavery. | 7a4b53ca-b07f-40f7-a5cd-610092ae5a66 |
433tau | Why do objects feel colder than the temperature of the air? | Heat transfers faster through conduction (touching it) than through convection (transfer through a fluid, in this case the air). The faster heat leaves your body, the colder you register it as. That is why it is colder in a windy place than a calm place of the same temperature. When it is windy you are in contact with more air in the same time, you lose more heat in the same amount of time, your body tells you that is colder. | 7ba3a767-58cb-4d92-8ca1-10aba54cfb95 |
4bc807 | When people have 'high pain tolerance', do they feel actually feel less pain or do they just tolerate it better? | Pain is in the brain. There is a part of your brain that translates stimuli from nerves into pain. If you would take this part out, you wouldn't feel any pain at all. In fact, there are people who are born without a functioning pain center in their brain. They usually don't live very long because the don't learn to stay away from hazardous situations.
As with everything in the brain, how it works differs wildly between human beings and it also can be trained. When you're gradually exposed to higher doses of pain you can expand your tolerance. So that's why some people have a natural high tolerance, others have it trained.
My experience as a physical therapist is that many people think they have a high tolerance for pain. But this also has to do with the fact that a majority of people think they are above average. Think about that ;) | 32825df5-8589-4943-9b11-f8a615b807bf |
qdnn0 | Why is it such a big deal that Apple has so much cash? | So, one part is because it's just a huge sum of cash....but let's go deeper
A public company's responsibility is to maximize shareholder value. The best way to measure that is growth in the stock price. How does a stock price grow...stuff like ROI, ROE and profits and such.
So the issue here is that that cash is doing nothing; it's just sitting in the bank and in risk free assets...meaning basically 0 return on investment (ROI).
The shareholders are saying, "Give us some of that cash through dividends so I can put it to work!" With the dividends, investors can invest in other securities to get some ROI.
If Apple was constantly using this cash to generate ROI, the shareholders wouldn't care. The problem is that the money is just sitting there and not creating returns for shareholders
Personally, I am torn. High tech companies tend to hold a lot of cash but Apple is just going crazy. Tim Cook recently said there isn't a reason to have *this* much cash on hand. We'll see what happens. | b1cab0c2-3b4b-476f-ae36-8136a24d3740 |
2xntas | How come if I wake up in the middle of the night, I often feel sweaty and gross, but if I wake up in the morning, I almost always feel normal? | You're probably waking up in the middle of the night because you're sweaty and gross. | 94a86f49-362d-48eb-b424-faf1bb1e6661 |
3o9ji4 | the difference between Yiddish and Hebrew | Hebrew is the language of Jews in the Middle East and of Jewish religious texts, it's a semitic language close to Arabic and Aramaic. It had actually died out, before it was revived as the national language for the state of Israel.
Yiddish, by contrast, is an amalgam of German and Hebrew (using Hebrew script most of the time, but as I understand way more German words/grammar than Hebrew). It was the language spoken by Jews in Europe with ties to Germany and Eastern Europe, as well as England and France. Jews tended to be socially and economically isolated for much of European history, and Yiddish was effectively a "ghetto" language that emerged from Hebrew being surrounded by all other languages, but Hebrew's speakers not being accepted enough by the speakers of those other languages to end up committing entirely to using the newer, local tongues. | 15dd551b-4c0e-4e79-a3a8-dd79ccaf80ab |
tw4dy | how the switch on the bottom of the rearviee mirror works. | There are two mirrors in a rearview mirror. That's why it's not super-thin. When you flip that switch you are moving one mirror out of the way and put the secondary mirror in place. The secondary mirror reflects less light and so doesn't blind you at night when someone has their brights on behind you.
To be a bit more technical it's one piece of glass with a wedge shape. The back of the wedge is very reflective (day mode) and the front of the glass is less so (night mode). Flipping the switch moves the back of the wedge out of line so it's no longer in your line of vision. | 1c5e08f5-d79b-4f1a-b17b-d93760c49708 |
2uegi0 | What gives atoms their various properties? | Yes, broadly speaking.
Atoms gain their properties due to their valence. Learning about this is basically most of the first semester of a college chemistry course, but the short version is:
Atoms are basically clouds of electrons surrounding a core of protons and neutrons. The clouds of electrons behave in a way that is random, but overall very predictable, and they try to form a pattern that resembles a shell of electrons composed of sets of four pairs to make an octet.
Bigger atoms have many shells of eight, smaller ones may have only one (or fewer than one complete shell) but it's only the outermost shell that really matters for bonding and chemical properties. When two elements bond, they share an electron or two to fulfil their octets.
Different atoms as you go down a row of the periodic table have different numbers of valience electrons in their outermost shell. These are what make atoms react differently. Lithium, sodium, potassium, etc, have one atom in their outermost valience shell - that means they want to bond very much with something that can fill their shell. If you put sodium in water, it rips the water apart, and causes an explosion as the oxygen and hydrogen heat up.
Likewise, flourine, chlorine, iodine, etc, all have seven electrons in their outer shell - they want badly to fill with things with only one electron, like hydrogen. That's why these elements can make such powerful acids - it's very easy for them to steal a hydrogen from water.
Carbon has four electons. It (and silicon, to a lesser degree) is the whore of the elemnts. It loves to bond with a lot of stuff becuase there's so many ways it can make pairs. Oxygen has six, so it loves to double bond (share two pairs of electrons) with carbon, or one each with hydrogen (to make water.)
Finally the nobel gasses come complete with eight already. That's why they hardly ever bond with *anything*.
There's more to this explanation than just that - radioactivity, transition elements, metals, different levels of valence shells, different types of bonds, subatomic forces, resonance, etc, but that is basically an entire chem course worth of information. But valence electrons are the most important thing overall. | dd0a179e-0b1e-46d5-9388-703033efd5e3 |
28h2o0 | How can Paper Lanterns be safe? Why don't they start fires when they land? | They do start fires. They're banned in 24 US states, according to the article below, because they're such a fire hazard.
_URL_0_ | ec596f8a-3081-4cb4-9a7c-879291244a35 |
5vyq68 | Someone commented on an askreddit thread that you can get drunk off of one shot by dipping your finger into it, and licking the alcohol off your finger over and over without actually picking it up and drinking it. How does this work, and is it legit? | You could consume all of the alcohol out of the glass, yes. Would it get you drunk? Not a single shot, no. They're full of shit. | 1599a1a6-5cb8-4000-aedb-fd27b444d787 |
4ccmpq | If I go without eating in the morning, waking up at 5 am and eating around 10:30 am I usually don't feel hungry. If I eat a banana or something after waking up, about 45 minutes later I feel like I haven't eaten in 3 days. Why is this? | Because eating causes your body to begin the digestive process, beginning before the food even enters your mouth. It starts with saliva production, and you gastric juice fills your stomach before the food is even there. If you eat something small, your body kicks into a digestive process, usually anticipating a larger meal, especially if it was the first one of the day. | 41b325e9-61f8-4ed3-bf0f-e12ec90a9150 |
2y4w7b | What is Cryptocurrency(e.g Bitcoin) mining? | What's happening? Basically, a computer is being used to perform a calculation, which gets more complex each time (each coin is harder to make than the last one). This is what keeps the value, it's a limited currency, there will only be so many bitcoins available.
People are slowly accumulating them. You put processing in to "make" a coin and it's now yours to use as you see fit. You may also join a "pool" of other miners. You share PC power, and get a proportional share of the value of any coins made.
Money is a concept, value for something. Merchants and people accept the value of these bitcoins, so they can be used for purchases as if they were legal tender.
Is it free? Essentially, yes, the software has no cost. The hardware to utilize it does have a cost, but many people already have something that would work (albeit, not well).
How long does it take? A long time. At this point, unless you have a server farm, you'll never get anything substantial from it. A standard computer might take days or weeks to mint a single coin.
Is expensive hardware needed? Not to do it, but it is needed if you want to make any sort of real profit. It only makes sense on a very large scale due to how complex the calculation has become over the years. | 111dc233-b683-46a9-9d37-563ad7af2489 |
17v1mi | How does reverse thrust on a jet engine work? | Most jet aircraft have "buckets". When stowed, these don't interfere with the engines at all. But when deployed, they form a barrier behind the rear of the engine, which directs the jet exhaust forwards, creating reverse thrust.
There's a very good picture of the buckets in their deployed position [here](_URL_0_).
Edit: I've explained how reverse thrust is created. Just noticed that you also said about it being used to reverse on the ground. As another reply has already said, it isn't. It's used on the runway after landing, to slow down. The reason it is not used for reversing is because a) it would blow dirt, stones, etc into the front of the engine, causing damage to the engine, and b) the powerful jet blowing at an airport terminal (if you were reversing out of a nose-in parking space) would likely damage the terminal building, especially if it has glass windows. | 494f174b-570f-41e4-9607-05cb09a3ea1a |
232en9 | Why are steel surfaces relatively inhospitable to bacteria and other germs whereas stuff like acrylic are not? | I believe it has to do with the surface and how porous it is/isn't. Bacteria need tiny holes to hang out in (which also traps stuff they feed on), otherwise they get brushed away easily and there is less available 'food' for them. Also some metals give off ions that apparently kill bacteria. I know silver does, not sure about other metals. | 04b586d0-7e3b-484d-874f-a9926f4510bb |
5tbwzu | It is estimated that some sharks lose over 30,000 teeth in a lifetime - where does a shark obtain the levels of calcium necessary for such rapid tooth replacement? | Well they don't have bones to worry about. We have a whole skeleton to upkeep, and we manage. But sharks eat a lot of things that have bones, and calcium in them, and what's more many calcium compounds can be dissolved in water, there are calcium ions just floating around the ocean, about 400mg/L of water. They don't really need anything to get calcium, they're swimming in a solution of calcium among other salts. | 7fc4c16e-9dbe-46ae-8741-3fe2819d6a78 |
2ta54m | What's the matter with phi and fibonacci in nature? | With regard to plants; Vi Hart has an excellent three part video on when it occurs, how it happens, and why phi in some plants is "inevitable."
[part 1](_URL_2_)
[part 2](_URL_1_)
[part 3](_URL_0_)
In all the other cases; the phenomenon doesn't exist. Or more clearly the only phenomenons are logical fallacies such as cherry picking and confirmation bias. | cb6af3a2-6ddd-46ae-bbfe-9d5f7556c709 |
4x50hm | How do scientists calculate the amount of calories in food? | They light it on fire!
No seriously, a calorie is a unit of measurement that measures the amount of energy it takes to raise the temperature of water 1 degree. In order to measure that, they burn things below a beaker of water and see how long it takes to raise a degree (I believe it is specifically one ml of water, but I could be mistaken.) | ff05110b-7e2b-479c-be09-9ee6620d7d6c |
5fj5kc | Why, as a non-smoker, do I occasionally get the "man, a cigarette would be great right now" craving? | You've probably seen the relief on a smokers face after not having one for a while and your brain has subconciously associated tobacco smoke with relief.
But the truth is every time we light up we're only relieving our need for nicotine. The stress relief is entirely in our heads. | d84a47a0-a259-47b6-9b95-3bd2a0839161 |
2v0pol | Why can schools ban peanuts but not enforce manditory immunizations? | "Do this" is harder to enforce than "Don't do this" | edef14a8-1878-491b-83c4-8bd0a11f8bd7 |
2ds4qm | What exactly are reverse mortgages? | In a normal mortgage, you borrow a large sum of money from a lender to be delivered up-front and repaid by you over a number of years, and the money you borrow is delivered by the lender to the seller of the property as the property is being purchased, but the money is "held" and released only once the mortgage document is signed; you receive a deed to the property, which conveys your ownership, and the Mortgage provides the lender a "priority claim" of ownership of the property, in case you fail to repay the loan.
With a normal Mortgage, over time, as you pay the loan properly, and do not fail to make payments --- your lender's "claim" to the property is gradually reduced, until you own the property 100%.
Your property always has a "fair market value"; this is the price that a buyer would be expected to pay for your property --- if you decided to sell it.
The "fair market value" varies over time and can be affected by many factors, but what's important to realize: as the owner of the property, you control this value.
The "fair market value" which you control as owner MINUS the total amount of money of all Mortgage debts, and other lenders' claims to the property is called your Equity.
If you have no mortgages or debts on the property, then your equity is 100% of the fair market value; you control this equity, therefore, you can offer up your property to secure a new debt, and your property will serve as collateral for the eventual repayment of this debt.
A reverse mortgage is basically exactly the same thing as a normal mortgage, except you already own the property --- if you have no debt on the property (which is pretty crucial), then you can pledge your equity to a lender and sign a Mortgage document providing the lender a claim on your property.
Instead of borrowing a "big sum of cash" all at once, typically how the reverse mortgage arrangement is structured --- you agree to receive a monthly payment from the lender (instead of making a monthly payment to the lender).
In exchange, the lender receives a claim to some of your equity over the property in the sum of the payment the lender sent you PLUS they will be due interest on the loan, until either the loan is settled, or the property is transferred to the lender.
Reverse mortgage payments to you will cease once a certain percentage of the equity has been exhausted, And: this level will likely be at a conservative amount.
In most cases, no more than 50 to 65% of the property's value will be paid out by the lender.
At this point, the mortgage still exists, but no more payments will be received from the bank, and interest on the debt owed to the bank or other lender will continue to accrue.
The typical arrangement is that there can be no foreclosure, and interest will continue to accrue, as long as the person who has taken out the reverse mortgage continues to live on the property.
Following the death of the owner and spouse, or if the owners decide to move or sell the property, the total debt including interest will be due to be immediately repaid in full as a big lump sum of cash to the bank or other lender, just as with a normal mortgage. | 5652fd3b-1540-4028-bf3f-0479f32a89db |
21bqsr | Do most North Koreans truely believe that their leader is a deity? | Obviously some do, likely out in the boonies but North Korea isn't nearly as tightly controlled as the North Koreans or the media would have you believe. It's certainly quite bad but Vice is know to "hype" their stories up a bit to make them a bit more entertaining.
The black market in North Korea is fairly large and the country is very dependent on it to function. This brings in many goods and information from outside the country which the North Korean authorities are largely forced to tolerate out of economic necessity. The average state worker is paid in the official rate and only makes in a month about enough to buy some cigarettes. Those workers make up the difference by working in the black markets buying and selling goods. That should give you some sense of the scale of those black markets. Organizations within North Korea have even begun advertising the black-market rate for goods in an attempt to attract investment. | 50a93622-1bd0-4f3f-9865-b1030f31e000 |
48qor3 | How were live television shows aired nationwide before the internet? | They were broadcast over the airwaves, like radio still is now.
Or they were broadcast by satellite to local stations, who broadcast it over the airwaves.
We were able to do a lot without an internet. Even invent the internet. | 3a2ce6e7-1520-4e99-b65e-968bdd8a0869 |
2p91ne | Why do I get the urge to jump when looking off a cliff or any high object? | > Imagine a person with high anxiety sensitivity. She leans over a ledge of the Grand Canyon. In super fast reaction to her physical sensation of anxiety, her survival instinct forces her away from the edge. Yet when she looks at the ledge, she sees it’s sturdy. There was never any danger. Her brain tries to process an answer to the question “Why did I back up if it was safe?” A logical answer is that she must have been tempted to jump.
>
> In other words, Hames explained, people misinterpret the instinctual safety signal, and conclude they must have felt an urge to leap. Hence the study’s title: “An Urge to Jump Affirms to Urge to Live.”
_URL_0_ | edbb0abf-83d5-43eb-b713-9ece86408f94 |
2a4dsn | Why do couples so often experience a decrease in sex drive shortly after marriage? | There isn't one good answer for that because for one, it isn't the same with each couple and two because it doesn't necessarily always happen.
One common reason though is simply time. A married couple will most likely spend their days working and by the time the day is done, sleep sounds like a much better idea than sex.
Another reason is that after a while, a couple's sex life tends to become a little bit boring. When you first start having sex, you're both willing to try different positions and other stuff to please yourself and your partner. After a while, you figure out what works and it becomes more relaxed and not as exciting.
Third, as you get older, your libido drops simply because that's how your body works.
But really, tons of married couples still have plenty of sex drive, but they often have to actively "spice things up" to keep their libidos up and continue to make sex exciting. | 1809ce4a-acdd-4d6e-83cc-be1197142b56 |
5c4esc | Why cold water tastes better? | I don't think it has to do with the taste -- I think it has to do with the refreshment.
Humans (and all animals) don't drink water because it tastes good, but rather because we need it to survive and cool down when we begin to overheat.
Since cold water is so refreshing, it's more enjoyable to drink. When a drink is more enjoyable, one would automatically assume that it "tastes" better, but I don't think that's necessarily what's going on there. | cb49e33b-5fd1-476d-9de4-46fc0ae9f948 |
39q6i1 | What is a transistor, and why was it's invention so revolutionary? | Transistors replaced vacuum tubes, which perform the same function: they both can take a small electrical current and use it to control a larger current. Both of them can be used as switches (in computers) to perform on- and off- operations (1's and 0's) or as amplifiers. Amplifiers are needed for radios, TV's and so on.
The big difference is that vacuum tubes are large, heavy and many need high voltages to operate while transistors are small and use low voltage. This allowed large, heavy bulky electronics to be miniaturized into small lightweight items like smartphones, PCs, and so on. | 9021d88b-5a3b-49cd-9d09-a3adf557ad0a |
4mctom | If the FBI supercomputer would take centuries to crack a certain password, can't they build several replicas of it and then solve it faster with cluster processing? | First of all, all modern supercomputers are actually clusters of relatively slow processors. So they already do have a cluster.
A properly set up 12 digit password using a standard English keyboard has 540,360,087,662,636,962,890,625 possible passwords (95^12).
China's Tianhe-2 computer holds the worlds record for fastest super computer and does 33.86 quadrillion math calculations a second (they are called Floating Point Operations Per Second or FLOPS). So for the sake of simplicity lets say it checks 33.86 quadrillion passwords a second. It would take 3 months to break the password(on average you'll try half of the possible passwords before getting it).
Thing is the cluster costs US$390 million and that's just buying it, not counting the cost of powering and maintaining it.
So millions of dollars spent, and you get to break a total of 4 passwords every year.
It's far cheaper to get a subpoena and threaten prosecution or just spy on the target, than it is to use super computers to break passwords.
That or just ask google really nicely. | 4c189121-6f30-41c5-94ae-c301a893e203 |
5vw8ng | If passwords are encrypted, why do I need to change my password on sites that use Cloudflare? | The term that's used is *hashed* rather than encrypted. You could argue that a hash is a form of encryption, but I think it's important to mention this because there is a difference - encryption is usually a two-way thing, you can encrypt it but you can also decrypt it to get your original text back. Hashing is one way - you can create a hash from a password, but you can never get the password back. The way that hashes work, on a practical level, is that when you log in to a website, it hashes the password you've just entered and compares it to the stored hash.
Now, being a one-way thing means that it's not possible to break the encryption and get the passwords out, but there's a few things that come into play now.
Best practice now involves *salting* the hashes, which I'll come onto in a second, but for a website that doesn't salt the hashes, what I might see is:
user1 5f4dcc3b5aa765d61d8327deb882cf99
user2 2ab96390c7dbe3439de74d0c9b0b1767
user3 a45da4b59a32dca94e2ffdd1d301c176
user4 2ab96390c7dbe3439de74d0c9b0b1767
The first thing to note is that user2 and user4 have the same hash next to them. Why's that? Because they use the same password. Basically, if I work out user2's password, then I automatically know user4's, and anyone else in the same file.
user1's hash is interesting, too - because you can Google is, and it'll tell you that user1 has simply set their password to *password*.
You can find 2 & 4 on Google too, because they've also used a common password. In fact, you can find useful things like tables full of pre-computed hashes that you can compare against a password database, meaning that you can find the users with that password fairly easily.
So, that's the low-hanging fruit. Once a hacker has got the easy stuff out of the way with pre-computed hashes they can try other techniques. You can try a dictionary based attack, where you start using words from the dictionary, start adding characters to the end and so on - so you might just start your computer calculating the hash of Ocelot, then Ocelot1, Ocelot2 and so on, looking in the file each time to see if the password matches anybody. And that takes a long time, but at least if you've got access to the password database the risk of being caught or locked out while you're doing it is far less than if you had to do it on a live system.
Now, I mentioned salted hashes - what you do with a salted hash is to mix the password up with something else before you hash it. For instance, if I stick the username on the end of each of the passwords that I used above, I get the following salted hashes:
user1 ddc5fba638b1990d84685c666a973de1
user2 26807a25bcaa4e907830debafa8e308a
user3 4bce4ae8996c0fd7352997975a3d5019
user4 f126beac703085c5fe82ed60d2139c3e
These have the same passwords as before, but with the benefit that knowing what one user's password is doesn't allow me to work out the others. Users 2 & 4 still have the same password as each other, but I'll never be able to find it in any list of precomputed hashes, and even if I do manage to work it out through brute force, I won't be able to figure out which other users have the same password.
This won't stop dictionary-based attacks, but it will slow them down because they won't be able to find the same hash used in multiple places.
The user that I've not mentioned here is number 3. They've used a completely random, 16 character password with upper case, lower case, numbers and symbols. According to one site that I checked on, it would take a computer about 2 billion years to get the right combination through brute force.
Now, if you find that your details have been compromised, it's important to think not only of your password on the compromised site, but on other sites. Have you reused it? A lot of people do, and there's a reasonable chance for some people that their e-mail password might be the same as the Reddit password and so on, so it's vital that you go and change the password if it's reused.
I'll mention one final thing, which is that I used online tools to create the example hashes and also work out how secure the random password is. Never, ever, ever put your password into a site other than the one its intended for. Sites that tell you how secure your password is might be benign, or they might be using it for nefarious purposes. I only used fictional passwords in my examples, there's no way I'd put my real password into any of those sites. | 04300ab1-4593-44d9-be2e-d25dadf5ce33 |
8k1bhl | What causes people’s voices to sound funny when they inhale helium? | We are accustomed to hearing vocal cords vibrate in ***air***.
Helium is lighter than air (that's why helium balloons float).
When vocal cords are vibrating in helium, they can vibrate faster, resulting in a higher pitch, because they vocal cords aren't pushing against the heavy air.
Similarly, if a person inhales something *heavier* than air (like sodium hexafluoride) their voice sounds *lower*. | 8ed03fe4-5f76-4bf1-be64-23189ba6d314 |
1p4znr | Why places like fast-food chains support either Coke or Pepsi, but not both. | With big chains Coke or Pepsi will try to get an exclusive contract, and they'll make an offer to sell really cheaply. IIRC Disneyworld gets theirs for free because it's such a big advertisement to have your product all over Disney. | 5f22fd20-381b-4638-b207-f181a2713c64 |
1m81or | Why can women have multiple orgasms while men can only have one? | Wow, I think these comments are way off the mark. Do you guys think that cavemen were running trains on the cavewomen? And "The strongest sperm" != The strongest offspring, considering the first sperm to reach the egg don't fertilize it as they die breaking down the egg wall. Also, human females are better with a single partner, that way paternity can be verified and it's more likely the male will stay to support his own offspring.
If a female can only orgasm once, they might do it before the male has finished and be done with intercourse. The female isn't getting pregnant then, so it is beneficial that females have no refractory period.
If a male orgasms and keeps going, he has a good chance of scraping out his own sperm (the shape of the tip of the penis was designed to do this to other male's sperm). But once he orgasms, his seed his in there and he can pack up. | 217daa15-9911-45a3-b25a-f100ce1da34c |
5pxq31 | Why do some people need to get up in the night and use the bathroom? Isn't that slowed down during sleep? | "Slowed down" is not the same as "turned off".
There are many reasons, from drinking fluids too close to bedtime to actual medical conditions.
Just like when you are awake, though, there is only so much your body can hold until it is time to relieve one's self. If it happens in the middle of the night, it can be enough of an irritant to wake you up and tell you to go... | 50d26fcf-e5df-4c1c-805b-1cef4bc3be93 |
2t48ux | What is happening when my computer, or phone, says I'm connected to the Internet, but it won't load any internet pages? | Depends on what device and how they detect "the internet". Typically, it's done via a simple low bandwidth connection to some sort of "home" server. It can even be as simple as a ping.
Now, remember how I said it's low bandwidth? That means that it uses a really small connection. Snapchat and it's ilk take up significantly more.
Additionally, there can be such a thing as "packet loss". Because the internet checker is so low bandwidth, this packet loss affects it much much less -- if at all.
However, when you use more bandwidth, packet loss starts to add up significantly. | 37f9598c-5be6-40b4-b571-f6189eacb7f9 |
3lwpkj | Soo, if we are flying around the sun flying around the solar system, flying around the galaxy...How are the stars we see at night in the same predictable places? | Because the huge size of space means that even if things are moving quickly (hundreds of kilometers per second), they don't change position in the sky very much. Let's do some quick example calculations.
First, you mention that we're flying around the Sun. That's true, we're moving at about 30 km/s around the Sun. But since we're going in a circular orbit around the Sun, we don't actually travel that far from where we started (relative to the Sun). The furthest we go is to the opposite side of the circle from where we are now, so twice the distance from the Earth to the Sun, or about 300 million kilometers.
Now, for reference, the nearest stars are about 4 lightyears away, which is about 37 trillion kilometers (really far!). If you use a bit of trigonometry (I'll spare the details, this is ELI5), you can estimate how far on the sky that star appears to move because of us orbiting around the Sun. The answer is about 0.4 thousandths of a degree. For reference, the Moon is about half a degree across as we see it in the sky, so the change in position is about a thousand times smaller than the Moon. And that's for the **nearest** stars! A star 10 times farther away will move 10 times less on the sky.
So that's the shift caused by Earth's motion around the Sun. What about the motion of the Sun? The Sun moves around the Galaxy at about 200 kilometers per second, which is 7 times faster than the Earth's orbital speed! But! Most of the stars around us are also moving around the Galaxy in a similar way, in the same general direction, so the velocity between us and the nearby stars is not nearly so high. Actually, it turns out that the relative movement of stars nearby the Sun is also about 30 kilometers per second, give or take a bit. So the change in position is about the same: less than a thousandth of a degree per year, for the nearest stars! There's no way that a human eye can detect that kind of difference. So it would take thousands of years for a star to appear to move about 1 degree (which, remember, is only twice the apparent size of the Moon in the sky). And that's about the amount of movement that you'd need to be able to pick it out with your eye.
Professional astronomers are really good at measuring the positions of stars: these days we can measure accurately even shifts as small as a millionth of a degree, or even less in some cases. So we can measure the change in position of stars over the course of several years, and we can use these measurements to tell us things like the star's velocity, how far away it is, if it's part of a binary star system (two stars orbiting each other), and other cool things. | 20b1dca7-7403-4516-8b75-5385fa75c4b3 |
7wtn3a | If antibacterial soaps are banned, what is ‘hand soap’ actually doing? | You've got a field filled with rabbits, and they're eating your crops.
Antibacterial agents and hand sanitizers are like poisoning the rabbits. The problem is that dead rabbit bodies are still strewn about, and some of the rabbits survive the poisoning, and their kids will also be good at surviving poisoning. And rabbits hold a grudge.
Scrubbing your hands with soap is like flooding the rabbit holes, and physically washing them off of your field. The advantage is that rabbits don't blame you for floods, and their kids don't grow up flood-resistant.
That is the strangest analogy I've ever thought of. | b27d2b5f-e3e0-4e00-a6de-519290b89cc9 |
87ytpr | why is human excrement brown? | There are a number of reason it's brown but the biggest contributor would be the presence of bilirubin. Bilirubin is a chemical that comes out of dead red blood cells. Basically, your poo includes expired blood, and that's brown. | 498e493c-e022-46f1-b39b-881eb8983a9f |
8x5r3i | Why does sunlight make it difficult to view our phone screens? | Because the sun is brighter. The little light particles from the sun beat the phone’s light particles and so you see what the sun’s light reflects, not what the phone’s light projects | 95049c41-ddcc-417f-ab61-f55d94dd68d4 |
4m2i68 | Why are some console versions of PC games not given the same treatment by the developers in terms of updates, patching, and DLC (i.e. Team Fortress 2 and Diablo 3)? | Every update, patch and DLC has to go through certification and quality assurance on consoles. That process takes not only time, but money as well. Depending on much your particular audience is skewed towards PC, it is understandable that some developers will prioritize putting it up on that platform first, and then rolling it out on consoles after a while, if at all. | e1b9f093-0a30-42a2-b55e-c2f06e2b60ac |
331ait | Why do I get so lovey-dovey when I'm tired? | Depends on what you mean by tired and lovey-dovey but probably due to the happy chemicals your brain releases when you're about to fall asleep. Dopamine and such. | 2dd61963-43c5-41cb-a433-88791bd41c16 |
1sbifl | When you're reviewing your research, how the hell do you find the null hypothesis? | The nullhypothesis is a statistical question.
It is the question you ask in order to disprove your hypothesis.
If you cannot disprove it with the data you collect, then the hypothesis must be correct.
(Well, most likely correct.) | 11e71647-db0f-46a8-a2ac-64491b55a40d |
3j0ukz | Why road construction crews don't re-pave bridges? | Because the bridges are likely made of concrete and the crews are re-laying asphalt. They are two different materials with different maintenance cycles. | fcd25374-3e75-47fd-ad92-019f1806ac8c |
2uwmi9 | When games on Steam go on sale dirt cheap, who makes the money, and how do they make profit? | Steam games have no physical product. This means that, once the cost of the development team is covered, there are no further expenses (simple situation, no multiplayer servers, etc). It also means that there is no difference in the cost of producing 500 copies vs producing 1,000 copies.
Game is priced at $50, and sells 500 copies. Total income is $50*500 = $25,000.
Game is priced at $20. It goes onto the "on sale games", and the "$20 and under". This means more impulse buyers, and it sells 1,000 copies. $20 * 1,000 = $20,000. Not quite as good, but still decent.
Now, it hits the $10 mark. Again, it's listed in the sale and the $10 and under category. More casual gamers will see it. Say 3,000 people decide to buy it. $10 * 3,000 = $30,000, which is more profit than the full-price sales.
These specific numbers were pulled out of my ass while I'm at the computer. Real companies have economists and researchers who have real-world data, and use it to determine an optimum price that allows for the most profit to be made. | 90ba5e50-3b57-4e0a-9bde-d98379e66c57 |
22thha | Dependent and Independent variable. | The dependent variable is what you are measuring (e.g. number of correct answers on a test).
The independent variable is what you are manipulating (or think of it like groups you are categorising people into e.g. gender (male/female), age (teenagers, older adults))
This usually leads to a hypothesis such as "There will be an effect of the IV on the DV". | db39103f-9802-4481-b674-1361403b9661 |
1uwinf | Animal House - ELI5 | You sure you're not talking about Animal Farm? | ed0e6ddf-028c-4c05-abbf-55b3cce56c5d |
rpikz | How are operating systems created? | Well, OSes like most software has evolved over time. They started out very simply and over time more and more features got added. Eventually they get to a point where all the new features make the system run too slowly, so that is when they do a larger rewrite, and they may redesign most of the OS from the ground up or they may use pieces from the last version. For example, between Windows XP and Win 7, there has been large rewrites to most of the operating system, but between Windows Vista and Windows 7, they reused some portions of Vista.
If you are wondering how people go about designing and building a new OS, then you have to understand what an OS does and how it interacts with the rest of the computer system. It's pretty hard to describe it ELI5, as OSes are a pretty advanced topic. I'll try to explain some of it and not get too long winded about it.
***How are operating systems coded?***
Like most software, an OS is written in source code by programmers and software engineers. The source code is broken down into many files, so that small pieces of the system can be written separately. The source code is then run through a Compiler, which turns it into a machine readable format and is then packaged into an installer application. The installer is responsible for putting all of the compiled code in the correct locations in memory so that the OS can start.
***How does an operating system start up on a computer?***
When you first turn your computer on, its a pretty dumb machine, its built so it will be able to start with a minimum of hardware attached. The first part that controls your computer is the firmware, often called a BIOS (Basic Input Output System). The BIOS is responsible for making sure all of the necessary pieces are plugged in (processor, RAM memory, hard drive, and the many components built into the motherboard), and it is also responsible for displaying the basic start up info on your monitor and taking input from your keyboard in case you want to go into the BIOS setup (or setup for some other component). The BIOS assigns Addresses/Names to all the components in your computer, it is basically making a map of all of your hardware, later the BIOS will give this map of hardware to the OS so that the OS will know how to access and use all the different components. All of this start up stuff is programmed into the flash memory of the BIOS chip on your motherboard, it's stored on the motherboard and not on a hard drive or in the RAM because all of these other memory locations might be removed from the computer, the basic function of turning on is stored on the motherboard since without that your computer has no backbone and can't function anyways. After the BIOS is done setting up, it has a setting stored in it (that you can change) that tells it where to look for an operating system, it might first look for any USB drives, then CD/DVD, and then a list of hard drives to check (since your computer might have more than one hard drive). If it looks on a hard drive, it looks in a part of the drive called the Boot Sector, which is an area set aside for booting OSes. In the Boot Sector (which is setup by the OS installer) there will be a pointer telling the computer where the actual Boot Loader is for the operating system. So once your BIOS finds the right Boot Sector, it learns where the Boot Loader is for Win 7 (or whatever OS you have). The Boot Loader is a special program that starts the OS, it takes the hardware map from the BIOS and turns it into something the OS can use, it also handles the loading of the Kernel and anything that needs to be in RAM for the OS to start. Once the Boot Loader is done, everything is setup, turned on, and running on your computer how the OS expects it to be, so the Boot Loader passes control over to the OS Kernel and you are displayed your login prompt.
***What does an operating system do?***
The OS is the main backbone program that runs on your computer. It's job is to be the boss of all the other programs you want to run. In order to have many programs running at the same time, it is important to manage what each program is allowed to do and when it is allowed to do it. The OS is responsible for assigning RAM to programs to use, when more RAM is in use than you have physically in your system, the OS is responsible for moving some of the data in RAM into a cache on the Hard drive (called swap space, or a page file). This allows more programs to be running then could fit in the physical memory for your computer. Your computer probably has multiple processing cores, each core can also handle running multiple things at the same time by switching between tasks very quickly, overall processors are very complex and it is the OSes responsibility to manage what program is running where, how long it gets to use the processor and what sorts of things it is allowed to do with the processor. So from your programs perspective, the OS gives it memory when it needs it, schedules it to run on the processor (without the program knowing about it), gives it access to the display for showing graphics, to the sound system for playing sounds, and whenever you touch your keyboard/mouse/gamepad the OS sends signals to the programs/games that are interested so that they know the buttons have been pushed. From the user's perspective (yours) the OS is where you start all of your other programs/games, its how you end programs that aren't stopping on their own, and how you switch between programs since you probably want to use more than one at a time. The OS is also responsible for a lot of security things, it makes sure that programs aren't messing around with the memory that is assigned to other programs (a lot of old hacks/viruses did this), it also allows you to limit which programs can access certain parts of your hard drive, or send information over the internet connection, and the OS tries to make it so that only the programs you choose to install get installed (although malware still likes to sneak in).
So, to answer your question about how OSes are created... Basically some teams of smart people look at all of these responsibilities (and the many more subtle ones that I skipped or don't know about), they look at how the OS is going to start on the system and how it can use the system while it is running and then they design all of the needed pieces. | b530103f-4d4c-4969-8a82-47a3aaa8182e |
3rdcrs | how did vanilla become the "generic" flavor | I'm just guessing, but I'd think that it's because Vanilla is such a strong flavour you only need a little bit of it, and because of that it doesn't impart much of a color to the food.
Look at ice Neapolitan ice cream....it's got pink strawberry, brown chocolate and white vanilla.
A lot of vanilla flavoured things are white (probably because food companies choose not to add food coloring).
But as a result of vanilla flavoured things looking white, it is associated with being 'plain'. And for some reason, people started using the word vanilla to describe plain or regular things.
The more you think about it, the less sense it makes. Vanilla is actually a pretty complex flavour and is anything but plain. | 29e315b0-08a5-4ef2-b786-c8a0fc1b7f1e |
5czcbl | Why are cans for canned goods not square? | Cans are round because it maximizes the volume per amount of metal used and because being round makes them stronger than cubes. | 3df9a50c-dc83-4f50-aa31-4b362d7472b3 |
2beiam | Why cross platform gaming isnt a thing. Like pc to xbox or ps4 multiplayer. Can this even on the smallest chance be possible? | For a lot of games, the controlls are just different between a gamepad and a mouse+keyboard setup. This is extremely noticable with strategy games shooters, but also comes into play with, for example, 3rd person action games. This means that it is very dificult to have a game that is exactly balanced between the different input sets and it's generally not a good idea to design a game in which half of your player base is inherently handicapped. | 82bf95d9-5fe9-4151-9d27-dfb33c65e0f8 |
1lftgl | Why does the north star never move but all the other stars do? | The others appear to move because the earth is spinning on its axis. Directly above either of the poles of that axis, a star will appear to barely move at all, but other stars will trace circles around it through the night.
You can take some cool long exposure photographs by pointing your camera at celestial north and waiting. Stars will smear out into concentric circles around celestial north. | 71c61d32-9108-4e93-bf93-7bcdb6874d0f |
2bg3qa | What makes something a vegetable? | A vegetable is defined as the edible part of a plant, unless that part has a narrower and more specific definition, like say a fruit.
You can tell if your vegetable is a fruit by whether it contains seeds or not.
Spinach and lettuce are vegetables, but your gourd or squash is a fruit. | 46667279-aead-4326-8493-eb3860971acc |
7itnyd | How can we so distinctly remember things that never actually happened? | It is possible to vividly imagine something and then simply re-categorize that mental image as a memory rather than something you imagined. The act of remembering it works just the same. You can see what it looks like, hear the sounds or voices, and so forth. You just have attached a wrong category to it. | 493bd787-b785-498e-9489-80945e52cda7 |
3grbzl | Why do large explosions result in a mushroom cloud? | [Wikipedia says](_URL_0_):
> Mushroom clouds result from the sudden formation of a large volume of lower-density gases at any altitude, causing a Rayleigh–Taylor instability. The buoyant mass of gas rises rapidly, resulting in turbulent vortices curling downward around its edges, forming a temporary vortex ring that draws up a central column, possibly with smoke, debris, or/and condensed water vapor to form the "mushroom stem".
So in ELI5-terms: the hot gas resulting from the explosion creates an updraft which pulls debris/dust from the ground up and forms a vortext at the top.
Check this diagram, because [images are better than words](_URL_1_) | f5008ba4-f8bf-42a3-b540-b732ee64fb3d |
2n2i0v | why isn't there more footage on the Internet of US soldiers in close combat (e.g. clearing buildings) situations? | When you are in close combat, you are at immediate risk of being killed. You have better things to do then screw around with a camera.
Now that cameras are very very small and wearable, and have longer battery life, this kind of footage will become more common.
A separate issue is that many military organizations prohibit sharing pictures or video taken during combat until it is approved by senior command. There is a strong desire to keep operational details secret, and to protect the identities of the people involved in case they are captured later. | 8db9f4dc-e826-410f-9cd9-cb1f0161440a |
2ep9s2 | how come some people have long, pointy canine teeth, which are longer than their regular teeth; and some people have flat canines the same length as the rest of their teeth? | How long your teeth are based on a few things. Mainly its because of the genes (traits) you inherit from your parents and their parents before them. Shapes and size of teeth are different in people from different races which is also a trait thing. Pointy-ness of your teeth depends on how much you use them. The more you use them the more they wear out despite being quite strong. This dulls the point and can make them flatter.
Canines are generally (especially upper canines) large, long and pointy because of the way they have been used by all the animals that have them. Over time they have become what they are to tear and hold onto things (like lions hunting deer). Sometimes they can appear longer if the tooth opposite the canine is missing. Teeth are always moving and growing into the mouth but things that come in the way stop them. If the opposite tooth is gone then usually nothing is stopping the canine from growing longer. | 12914b47-e41e-42b2-9b49-10399608d46f |
285u9d | Why does everyone hate comcast? | They stand against innovation by working in what is essentially a monopoly. They have outrageously high prices for outrageously low-quality products. Other countries have internet that is 5-6 times faster than Comcast for half the price. Why is Comcast able to do this? Because they have 0 competition.
Basically, they are able to do whatever anti-consumer policies they want because there's no other company to give them competition. Customers *have* to deal with it in most cases. This ends up with them raising prices, adding fees, having terrible customer support, having a low-quality product, and overall halting the innovation and expansion that the internet provides.
TL;DR Their company policy isn't: "You'll want buy our product because it's the best available" It's: "You'll have to buy our product because it's the only one available. | 6b59bd8d-7b92-417c-9bd5-a3a02f77105e |
3e37do | Why does amazing art, in whatever form, have such ability to inspire, motivate and evoke such strong emotion? | Hi. Art grad here. Let's begin.
First off, art is subjective. Now there are things such as the Frozen movie that is loved by most, and that is because the general population of the targeted audience enjoys similar qualities in things. What I'm saying here is that not all art will have the same effects on everyone.
About art that might have those effects on someone. There are things in art that artists use to specifically and intentionally activate things such as motivation, emotion, and inspiration. In color theory, there are various colors that are often used to do this. Red can mean things such as hot, fire, hell, burning, and love. Blue can mean the opposite of red, such as cool, water, and sky. These colors can mean these things because on a deeper level, things in life are these colors and we have grown up with that reference. On the psychological level, those feelings are established in connection with the colors.
Outside of color theory, but in the same way, artists utilize things such as the angle of a line, blurring, object placement, scene composition, and other elements because we know how things visually connect with psychology. | 14474832-b58d-4a36-9a66-2faffac66ab1 |
1btrd0 | Why won't printing more money solve economic problems? | Back in the Nixon Administration, all currency was based on the gold standard. This meant that you could take a $1 American bill and exchange it for gold at a federal reserve bank. Because of this, a crisis arose in the seventies because foreign countries would collect American money and exchange it for gold. As the U.S. gold deposits depleted, the value of the dollar went down because less gold backed up the bill.
In response to this crisis, Nixon took the dollar off the gold standard and U.S. currency is backed by the full faith and credit of the U.S. government. Basically, because our government has stability, our currency has value.
Now while this may seem a silly idea, it's the status quo, many nations use this system, so everything is hunky dory. Because some people disagree with this system, it's a motivation for people to buy gold and silver commodities.
To respond to your original question, think if things this way; the holographic Charizard Pokémon card was valuable because there were not very many circulated. But if everyone had a holographic Charizard card, then it'd be like having a regular Pikàchu card. So if more money is printed, it's not as valuable.
As currency loses value, we call this inflation. With inflation, the cost if everything rises and if wages don't keep up with price increases then the people become poor. | 06227a79-38c3-4c09-93be-181ff34a2eeb |
3e48ma | if putting dogs to sleep is such a widely accepted process, why is human euthanization so controversial? | > I understand that there's a difference between dogs and humans.
If you understand this then why are you still asking this lol? In the most formal way possible, the answer to your question is that society doesn't consider dogs to be legal persons entitled to rights while it does consider humans that way. | 5ed053fa-fdb6-40ef-84d4-545f6ed81a9e |
33ztxq | Why do people on reality survivalist shows bring firestarters instead of a lighter? It seams that a disposable lighter would work much easier and last more than the 30 or so days that they are in the wild. | Because if they wanted to do things the easy way they wouldn't be on a survivalist show in the first place. | f31b6679-c73b-4d82-833e-ac20a69c435d |
4hae3n | Why do restaurants have so much trouble splitting checks? | Splitting a check in half, like a 50/50 charge on each card is not too hard.
When three couples split at the end, though, the server has to go back to the restaurant's order system and basically recreate 3 separate checks from scratch, voiding and reentering all the food they already input while sending a separate message to the kitchen NOT to prepare it. There's also the act of figuring out which items are for whom and how they'll be paid. Imagine ringing up a family's groceries and then at the end, they say "can you take all the meat, dairy, and the coffee and put it on this card, then take all the produce and bread and put it on this card, then put the snacks and cleaning supplies on this other card?"
Most servers are running multiple tables, and even with a list of everything ordered they may not remember exactly who got what.
EDIT: depending on the software of the order station, this can be easier or more difficult. It usually depends on the size of the restaurant and how much money the owner is willing to invest in the order system. Smaller restaurants that use paper tickets only and ring you up at the end, it's probably easier. Larger restaurants with multiple order stations spread out over the entire area all talk to an order screen in the kitchen but also double as a register for charging cards, printing receipts, etc. Even the most advanced order system will have you "click and drag" or "copy/paste" orders to create separate checks. This can be time consuming. Add the fact that these order stations need to be used to input orders as well by multiple servers and it's easy to understand why splitting checks can be a problem. Imagine splitting the check four ways for a party of 10 who ordered multiple drinks and entrees but also wanted to split the cost of two different appetizers four ways, all the time your coworkers are lining up behind you to input THEIR tables' orders.
Source: waited tables in college. | e3f91bdd-4373-4e06-8f6c-34d396471eab |
2w0tmy | How do speakers of Japanese, Chinese and other languages with pictographic writing systems organise their dictionaries? | Japanese does have a common way of ordering their sounds. It is the order they use for their hirigana (Ka, ki, ku, ke, ko.) So some dictionaries get ordered in that way. (well, Japanese - english dictionaries do, at least).
Then another way to order them would be by kanji radical. Kanji are made up of several reoccurring pieces called radicals. So if you would come across an unknown kanji, you could use a kanji dictionary and start looking up things on a radical base. Radicals, as far as I know, are ordered by stroke order, from least strokes to most strokes | 9fea55cf-df7a-49f4-b00d-c211ae3175d5 |
7bsh1c | We have vitamin A , B, C, D, E and K but not F, G, H, I and J. Why? | Vitamins A through E were named alphabetically. Vitamin K was discovered later and is essential in coagulation. But when they name it they spelled it koagulation. | 820a4d42-5a2b-4092-9fda-d98a1727e320 |
8keez6 | Why does exercise such as running or cycling feel much more strenuous during the first couple of minutes? | Blood is constantly pumped all around our body to supply oxygen to all our muscles. In the case of running and cycling, we predominantly use our legs, but seeing as though we still have a regular blood circulation, our muscles find it difficult to work comfortably due to the lack of oxygen for the task they are performing. So, our body makes the decision to divert more blood towards those specific working muscles through the contraction and dilation of the blood vessels.
This is why people tend to do a "warm up" before going on a run or cycle as it helps raise the heart rate to a level where your body would be comfortable performing strenuous tasks | 033526ee-4800-4086-b4ee-e68c7dd99415 |
2ze2zy | Why do I feel like I'm going to vomit when calling a stranger on the phone? | While I am not a doctor, not your doctor, and this is not medical advice, it sounds very much like you are experiencing a panic attack, possibly brougt on by social anxiety.
The same thing happens to me, on the phone.
You might wish to seek treatment. | d881f3eb-d22c-4bb1-93ef-c73d174f40b9 |
6jx98a | How is colour and temperature related when something is burning? Also, why does the Sun appear white? | The purple may be an artifact. On some digital cameras, infrared shows up as purple. The blue filter lets some red through. I use the selfie cam on my iPhone 6 to test IR remote controls. The main cam does not do that. | 9b60f02c-4477-4135-9c5a-d94c377eeb4a |
4zfrar | Why were people shown as having pure white skin in ancient asian portraits? | Pale skin was in China, as in Europe at one time, a symbol of the upper class--you cannot avoid being tanned if you perform outdoor labor. It's long been represented in art, dolls and make-up fashions as a beauty ideal. | 32205298-6bd6-4c34-8729-4f1c6587b9bb |
j2tw7 | How does a ponzi scheme work? I'm 5 years old. | #1. you borrow lots of money, and promise to pay it back at huge interest rates over a long period of time.
#2. you live like a king spending money on whatever you like until the money runs out.
#3. you borrow even more money to pay off the original loans.
#4. repeat this until china stops lending you money. | 9f85acfd-bef7-4eed-a549-0ca96745dd04 |
1rejjz | How did BBC get the seemingly impossible footage for David Attenboroughs Life series? | Many many many hours of waiting. You can watch documentaries on how they film those documentaries. It involves cameramen being out in the field for months, being bored out of their minds while waiting for that opportunity to get that perfect shot. | 399f6048-4609-439e-9b0f-aafada5a040e |
6g62z0 | What is physically different about a hard drive with a 500 GB capacity versus a hard drive with a 1 TB capacity? Do the hard drives cost the same amount to produce? | Here's an analogy that a five year old might understand.
Imagine you have a piece of paper. You get your crayon and divide the paper up into squares. In each square you can write a limited amount of information (for this example, let's say one letter), [like this](_URL_0_). If you tried to write any more information in each square, it would be unreadable because the crayon is too thick to write smaller letters.
You can make more storage space by creating a book using more than one sheet of paper. The extra paper costs more money compared to using a single sheet. Another way to make more space is to replace your crayon with something smaller, and more expensive, like a pen. You [can see](_URL_1_) that more information would fit on the sheet compared to when you were using a crayon.
Once you've made your large storage device using multiple sheets of paper and a pen, you might want to make artificially smaller sizes (read about price discrimination for more on why you might want to do this). You can do this by removing some of the sheets, or by painting over some of your squares [like this](_URL_2_).
To get back to your original question: The physical differences are different numbers of platters (the sheets of paper in the analogy), and different density on each platter (the different writing sizes in the analogy). Whether they cost the same depends on how a manufacturer decides to produce their different sizes. If they use fewer platters, it might cost less to make a smaller drive. If there is no physical difference and they just disable part of the drive for their smaller capacity drives (painting over squares in the analogy), then all sizes will cost the same to produce. | 16bf1b17-c540-435b-b097-0ae1de949551 |
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