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c5xatm | if stars are said to have been burning millions of years ago and we only see the light now, how were their constellations that are still correct today | Constellations are just how patterns of stars appear from earth.
The stars may not even be close to each other, due to differences in brightness.
In the last few thousand years, the shapes of constellations have changed slightly, Anson a few thousand more many will appear different again. | cd56135f-ce5b-49bc-83cc-6d6e5a9e1488 |
c5xcjz | where does the wax go when you burn a candle? | It burns. You just said you are burning the candle, the candle wax is the fuel which burns. The wick is just a way of bringing a small amount of it up to be vaporized where it can burn, it isn't some magical string that burns for a long time.
Burned wax turns into things like soot and water vapor, a complex mix of partially combusted byproducts. Ultimately though the bulk of it floats away in the air. | ac814edc-03bd-4a05-965b-bd283d14019e |
c5xe5y | Besides looking ridiculous, why is it that cars with a lot of horsepower can't tow while trucks with less horsepower can? | All the responses so far miss perhaps the most important thing: brakes. With the right gear ratio, even a weak vehicle can get a heavy load rolling, but trucks that are designed to tow have braking capacity that greatly exceeds that of the vehicle alone. A Corvette has big vented brakes to produce impressive stopping specs from high speed, but it’s not going to stop safely with four times its own weight.
The Society for Automotive Engineers (SAE) has a standard for this. SAE J2807 is defined as “Performance requirements for determining tow-vehicle gross combination weight rating and trailer weight rating,” the standard measures a vehicle’s ability to safely tow by measuring braking distances, acceleration times, passing ability, grade-climbing ability, and physical load-carrying capability. | 52c7affb-3750-4056-94d0-3e4873589a51 |
c5xyac | How can certain foods have so many more calories while being so much less material? For example 3 Oreos have more calories than a whole can of tuna. | Oreos are basically sugar and fat.
Sugar is 4 calories per gram, protein is 4 calories per gram, fat is 9 calories per gram.
100g of Oreos contains 69 grams of carbohydrate, 20 grams of fat and 5 grams of protein. Which means 100g of Oreo contains around 500 calories.
Tuna is mostly water.
100g of tuna contains 0 grams of carbohydrates, 1 gram of fat and 20 grams of protein. For a total of about 90 calories.
Size of food isn’t important, composition is.
This is exactly why so many people over eat. | 654ccf54-cddf-42fe-85e4-d9e6f24af78c |
c5y13n | What would happen in the extremely unlikely event absolutely nobody in the entire USA casts a single presidential vote | it literally can be a coin toss since its a percise tie
"So how would states pick electors in the absence of votes? Article II, Section 1 of the Constitution says that electors are appointed "in such manner as the Legislature thereof may direct"—in other words, they have some latitude in picking these guys. If there were zero votes in a presidential election, the race would essentially be a tie, state-election authorities "would have to turn to the tie-breaking methods that are either statutorily established, or established by custom." | 07d283c7-e061-485b-8be4-3ca69691daf4 |
c5y8b4 | How are dinosaur footprints fossilized? Wouldn't the mud or soil that they were formed in get washed away in rain or some other quick erosion? | The vast, vast majority of footprints do get eroded away. Actually getting fossils is vanishingly rare.
In order for it to happen, some layer of sediment (from a flood, or volcano, or whatever) has to cover over the footprints (which have to be stable enough not to get obliterated by this), and then that layer has to be fossilized into rock. Everything has to wind up just right....but if you consider how many footprints dinosaurs must have left during all those millions of years, it's not surprising we still have a few left. | 32220847-7f4c-4209-a42a-a04b05008622 |
c5yb7t | What is happening to my body when withdrawing from an SSRI results in cold night sweats? | Having some hardcore withdrawals is what it’s doing. SSRI’s are known to potentially kill people that just quit them cold turkey. So if you think missing one dose is bad imaging not taking it for a couple weeks. | 59f8a8ba-bb71-42ab-b28e-07efd04904bd |
c5yhvs | Why is it that say I'm using a gel ballpoint pen (Pilot G2 Gel - not sure if it matters) even though there's ink in the pen, on some parts of the paper, no ink comes out but then after writing somewhere else, there's ink? | Paper was too slick. Those pens need friction to move the ball at the end of the point and transfer ink to the paper. If the ball doesn’t catch on the paper and move, no ink.
Also gel pens have thick ink so it doesn’t always come out at the same pace. | 96193cdf-abda-46e5-8130-0e730327cb31 |
c5yobl | Indo-Aryan people and Indo-Iranian people | [Explained visually](_URL_0_)
There's a person named Proto-Indo-European who had many children:
* Proto-Balto-Slavic (ancestor to modern Russian, Polish, Latvian, etc.)
* Proto-Germanic (ancestor to modern English, German, Swedish, etc.)
* Proto-Italic (ancestor to modern Spanish, French, Romanian, etc.)
* Proto-Celtic (ancestor to modern Irish, Scottish Gaelic, Welsh, etc.)
* Proto-Greek (ancestor to modern Greek)
* Proto-Armenian (ancestor to modern Armenian)
* Proto-Albanian (ancestor to modern Albanian)
* Proto-Indo-Iranian (let's discuss below)
Proto-Indo-Iranian, had 2 children:
* Old Persian
* Old Sanskrit
These two children each had their own descendants. Old Persian's branch is called the Iranian languages and Old Sanskrit's branch is called the Indo-Aryan (or Indic) languages.
Modern Iranian languages include:
* Farsi (Persian)
* Kurdish
* Pashto
* Balochi
Modern Indo-Aryan (Indic) languages include:
* Hindi/Urdu
* Punjabi
* Gujarati
* Bengali
Fun fact: the Roma (the derogatory term is Gypsy) people in Europe speak Romani, an Indo-Aryan language. This ethnic group originated in modern India/Pakistan.
Languages, related or not, borrow words from each other all the time. Much of South Asia was ruled by Persian speakers and because there was so much linguistic diversity in the region, Persian became the lingua franca so people from many linguistic backgrounds could understand each other.
The local languages also took on many Persian words. The more northern or western these languages were (Sindhi, Punjabi, Gujarati) the more they were influenced by Persian, compared to those in the east and south (like Oriya, Bengali, Assamese).
It's important to know that Indo-Aryan languages do not include those spoken in South India, such as Tamil, Telegu, Kannada, Malayalam. These languages are part of the Dravidian family and thus not related to any Indo-European languages. In other words, Hindi is more closely related to English, Ukrainian, Italian, and even Yiddish than it is to its neighbor, Tamil. But like I said above, languages, related or not, borrow words from each other all the time, especially neighbors.
My family speaks Gujarati and I took Farsi in college. Picked it up pretty easily, especially because of the many shared words and grammatical structure. It just made sense to me and I hadn't really spoken (but still understand) Gujarati since I was 6. If you say the numbers in Gujarati and Hindi and compare them to Farsi, it's like comparing the numbers in French to Spanish. It's like 80-90% the same.
I had an Armenian math teacher in high school who taught me 1-10 in Armenian. Not that dissimilar from Gujarati. | 66cb5e0e-269e-44e8-883b-047af7a3fa74 |
c5yuqq | Why are electric car battery estimates so much more accurate than laptop and phone battery estimates? | Have you edited your laptops critical battery settings? They tend to toss themselves into hibernation when they hit a predetermined critical level of battery by default, usually 4-7% at factory setting. | a9532b41-4af2-41ab-8192-4a7e3b541192 |
c5ywmi | What does it mean to “seek asylum” and does it justify people crossing the US border illegally? | Asylum is a legal request to stay in another country because you fear violence in your original country. It was originally intended for persecuted peoples (eg you would be killed for racial or religious reasons.). However, in the US the Supreme Court established precedent that a woman fleeing domestic violence could ask for asylum. This established the principle that anyone could come to the US and request asylum for fear of any kind of criminality or violence. Combined with bureaucracy and due process concerns, it is very easily to exploit the system.
An asylum seeker has no reason to cross the border illegally. Asylum claims are a request made to the host country’s government. Therefore, the asylum seeker’s claim must be made to an agent of the government so that their case can be adjudicated. If a person gets caught crossing illegally and THEN claims asylum, that’s a good sign that they are liars. | f6bd4a7b-53b9-4506-acb6-ecab497d309c |
c5ywz8 | What is the purpose of the eyes iris and why does it's colour vary among individuals? | The iris controls the amount of light let into the eye. When it's brighter out, the iris is larger making the pupil smaller and letting in less, but light. When it's dark, the iris is smaller, making the pupil bigger and letting in more light.
& #x200B;
The color is due to melanin (a brown/black pigment that also affects skin color) interacting with blood vessels, connective tissues and other stuff in the eye. The color has a little bit of an effect on vision. Lighter colors tends to be a bit better at night vision and darker colors tend to be a little better in bright lights. I don't know why though.
Edit: added more about why eye color is different and effects | 3f0103b3-0c6e-4983-ad45-7725b16dc35d |
c5yyu4 | How do people depict dinosaur sounds despite not knowing what they actually sound like? Or do they just guess and just go with it? | So animal sounds, like the human voice just rely on air running past/through some kind of resonator or 'voicebox'. I remember in a highschool biology lesson we got a pig's lungs and heart to dissect as a class demo, and the teacher showed how the squeal /grunt could be replicated by using a hand pump to pass air through it .
I'm sure I recall you here being an attempt to recreate the 'voicebox' of a fossil in a similar way [link to a similar article, but not quite the one I was thinking of](_URL_0_) | bac05ce8-f24d-4724-a590-8bd94612cebf |
c5z47a | Why is it that the planets in our solar system were formed very quickly (within 1/2 a billion years) but we havent had any new planets formed since then? | Because the matter in the protoplanetary disk got used up. | e3a7e85c-e88a-4fa3-abd0-2e9e7a159e37 |
c5z493 | When a large company is broken up via anti-Trust litigation, how is it decided who owns the new, smaller companies? | The same people who owned the larger company get an equal percentage of each of the smaller companies. | c26221f0-0a6f-40e6-8267-bf9dc5bbad52 |
c5z5nc | Why do organisms that live in prolonged darkness slowly lose their vision? | You mean as an individual or as a species?
Individually, an animal born into darkness can permanently lose their vision. Their brains never develop the ability to process their visual stimuli. There are some sad but interesting studies done on cats about this. If an animal learns to see correctly but then spends time in darkness, they may lose their vision temporarily but not permanently.
As a species, an animal that lives in darkness can lose their eyes because they are no longer selected for. In the above-ground world, an animal with good vision is likely to avoid predation and out-compete an animal with poor vision. A blind animal is likely to die. But inside a dark environment (eg lizards or fish inside a deep cave) it does not matter whether an animal is blind or not. An animal born blind or with an eyeless birth defect is just as good as a sighted animal, and therefore equally likely to pass on their non-sighted genes. | d4a077b1-949d-435e-a373-5585ffda2201 |
c5ze53 | Why are birds attracted to shiny objects? | The general theory is that birds are not attracted to shiny objects as a whole but a couple species have a higher tendency to find shiny things and use them to attract mates.
The idea of "thieving magpies" has more or less Been proven not to be true. | 7d9fed0d-3fbf-4691-9de6-8fab1fe0f88f |
c5zeif | Why when we do a relaxation / meditation before sleep we feel a tingling in any part of the body that we want and, at a certain point, we stop feeling the body and the relative position of each part of it? | I think you're describing your body paralyzing you in preparation for bed.
So in R.E.M. sleep (if you don't sleepwalk), everything except your face (and breathing muscles) is paralyzed. There can be a sort of tingling sensation during this process (can vouch as both a wake-induced lucid dreamer and a frequent experiencer of sleep paralysis) but it usually passes as you fall deeper into sleep (or gets worse as you wake up with sleep paralysis).
However, meditation might be stimulating that process to happen faster. I haven't meditated close to sleep lately, so I don't recall the exact process, but it seems the most likely explanation. | 21fe2cd6-d445-4623-b42a-8c1d269d9f7a |
c5zkl7 | when you get surgery or any other kind of major cut on your skin, how do the blood vessels and nerves know how to line themselves back up when its healing? | They don't really. There is some angiogenesis, where new blood vessels are built. They may or may not cross back across and connect with other blood vessels. If they do, it's just them growing until they bump into other vessels. It's not like a bunch of hoses that have to get reattached to all their other halves. And nerves don't always grow back. Lots of of lacerations remain sort of numb after the scar forms. Sometimes peripheral nerves will grow back, through a process called Wallerian degeneration. It's pretty cool, and there are some good youtube videos about it.
Your blood vessels aren't just a loop that can be cut and have to be repaired. It's more of a vast network that has general direction of flow through it. | cb29ebe1-ab1c-47e1-94b5-8f946dd2af84 |
c5zm70 | How do they know when it’s time to repair a highway overpass or bridge before it’s too late? | Proper and timely inspections are the key. You check for metal stress and deterioration. It’s easier to do minor repair than to build a new bridge.
Unfortunately, there’s “never” enough money or resources to keep up maintenance but you can better believe there’s enough resources to float a bond election to pay for the replacement of a bridge and the general contractor for the replacement just happens to be the governor’s best friend. | f63c150c-7d50-4900-a934-f1d21f5a6b67 |
c5zqxm | How were 2 countries able to discover and build nuclear weapons from scratch, simultaneously during the 1940s but most countries today can't build them without decades of effort? | The US threw an assload of money and resources at the problem. The Manhattan Project budget was over $20 billion (2019 dollars) and employed over 100k people. The US also had the advantage of not having to worry about other countries boycotting or embargoing them for building the bomb. Countries these days can face severe trade sanctions if they get caught building a bomb. The major nuclear superpowers are also the ones happening to sit on the large uranium reserves, so if you want to build a nuke, you need a fuel source and the big boys just aren’t going to hand over a ton of ore for you to play with. | c4123875-cf81-46f6-819a-68461a903594 |
c5zrz7 | Why do offshore oil rig leaks take so long to stop? | So part of it is that Taylor energy basically lied about the amount of oil still leaking. Taylor Oil said it was leaking 3-4 gallons a day, but the government is saying it could be close to 4,600 (or 71,000 I don't know).
Oil wells in the ocean need pipes to bring the oil and natural gas from far below ground to the surface where it can be processed. During a hurricane these pipes were broken. Because the broken parts are so far under the water, it's just really really hard to actually get down there to actually do anything. And once you're down there it's really hard to fix anything because it's underwater. In some ways, it's easier to do stuff on the moon than deep underwater. | 338b10e0-ad90-43b5-ba68-2b85e767412c |
c5zssj | Why for most sports Olympic gold is the top achievement, while in boxing Olympic games are considered an amateur level? | Because most Olympic sports don't have the potential for their athletes to earn hundreds of millions of dollars.
If a top pole vaulter could make $80m by going head to head on pay-per-view with another top pole vaulter, nobody would care about Olympic pole vaulting. | bd4a9497-69a8-4b0b-be88-9f8e834f3cde |
c5zxnd | Why can steak be pink/red inside when you eat it, but chicken can’t be? | It's a matter of foodborne pathogens - bacteria, parasites, etc. The types of pathogens in chicken (particularly salmonella) only die at higher temperatures, helping minimize the risk of foodborne illness.
In theory, you *can* eat chicken - or almost anything, for that matter - raw. There is even a particular area in Japan that has a traditional preparation of chicken sashimi (thin, raw slices), which uses only specific chickens harvested locally and freshly to minimize the risk of illness. Even then, it's still probably not a great idea to eat raw chicken. | 9cf49e38-fa1b-4171-b10c-a35e8f50fe13 |
c5zz4f | How are mobile check deposits accepted by banks if they never even get to see them up close? | Essentially they use an ACH system to “cash” the check before you are given the money.
If the check were fraudulent they would know before it is fully deposited into your account. | 1ad47ef5-d6f3-4ec7-8dbc-3847ee74e674 |
c60a2l | Credit Card interest | A credit card is basically a short term high interest loan to you. The average rate for a new cardholder with no credit history is 19.24% APR (annual percentage rate). So if you buy something with a credit card, that money is being loaned to you, and that interest rate is applied every month that you go without paying it back (based on the number of days in each billing cycle that passes). If you go a full year without paying, the full interest applies to the amount from that first month. You're required to pay a certain minimum amount each month that you maintain a balance on the card, this amount is not enough to keep interest from building up, but keeps the card issuer satisfied while you get deeper into debt. | 0fe9eb6f-eb07-4d3c-86cf-24c8d6a42573 |
c60pcn | Why did people come to the conclusion that smiling in photographs was the best way to take a picture? | When photography was first, um, _developed_ it was a sloooow process. So the best way to get a non-blurry photo was for the subject to sit as still as possible while the exposure was made. That “still as possible” posture would have likely included a closed-mouth, reasonably somber face.
As the speed of the process increased, it got significantly faster to take photos, and it would have been simpler to get photos of more fleeting moments, like people smiling.
And people enjoy looking at happy photos more than at somber ones, too. | 04d29a5c-2303-45dc-b9e5-2cfae2d89002 |
c612ju | Are human beings still evolving? | Yes. Just in different ways now. What used to be considered a quality of survival is different. What is “weak” and “strong” has changed, so the process of natural selection is not the same as adaptive animal species. We have medicine. Technology. Public health management. Big muscles and tall height don’t inevitably lead to procreation anymore since our drive as a species is more complex than furthering our genetic lines. | b5455a7d-9f6c-4dc4-a344-12465fa98d67 |
c616rk | How do insects breathe? | It's pretty varied, across different insects.
The common characteristics are that air enters the body via spiracles (basically holes in the exoskeleton, sometimes valved) and then flows through trachea (a network of breathing tubes) to the entire body. Entirely separate system from circulation.
& #x200B;
This is what limits the size of insects, they need surface area for spiracles, but body mass increases far quicker than surface area as they get larger. During periods with greater oxygen concentration in the atmosphere, you got REALLY big bugs like 9 foot millipedes... | 188a1e27-d2be-4f39-84e1-bd6f4878d9d6 |
c62tap | Why does your body not allow food to come in when you’re sick? | If it's viral, the lining of your stomache will likely be irritated. Eating and digesting the food would only irritate it further so your body expels the food.
It's your body's way of protecting you from harm down the road.
Imagine a small cut on your arm as the irritation in your stomache, and eating/digesting food as rubbing the wound with your hand. | 7f34ed47-69b0-4e0d-ae11-98805c5cdfbe |
c62u4n | why is it when a person feels a lot of pain and/or sudden coldness/hotness their immediate reaction would be yelling/shouting? | Just guessin here. But as humans are social group creatures. When you are in a group and you get hurt sitting there quietly isnt going to net you any group assistance. I can imagine the ones that didnt cry out wouldnt get the help they needed to survive, thus removing them from the genepool?
Not an expert on the matter though. But it sounds plausible in my head. | 0a1ee7ba-1f0c-46fa-8656-731e5b9dfa12 |
c62wez | if someone is a citizen of 2 different countries, do they have 2 different passports? | Yes.
Passports are issued by each country separately, there's no such thing as a "multiple country" passport. | 9c78d574-6252-4edb-9fe2-a823f8de12f8 |
c637gp | Do people with bigger heads have more brain capacity than those with a smaller head? | Not really.
The brain capacity is much more decided by it's structure than it's size. Early hominids had growing brains when they developed more intelligence but that's not really important between individuals. | 53fa2b5d-5229-4378-aa9d-05180af77eaf |
c63g57 | Why does it sometimes physically hurt when bright light hits your eye? | Pain is just your brain's way of telling you something needs to be addressed.
you cut yourself:
*ouchies*, better get a bandaid
get too close to fire: *ouchies*, better move my hand away
with that in mind, bright lights can damage your eyes. especially if it's sunlight. the physical pain is your body's way of telling you to stop staring at such a bright light.
and as with most health stuff, everyone is different. some people are more sensitive and can barely go outside without sun glasses. others could stare straight into a projector bulb and not think twice about it. | c9fdad66-fff6-4813-b2c1-cabad84fe273 |
c64by5 | Why does it take 24 hours for muscles to start hurting after a workout? Why not straight away? | This is called [delayed onset muscle soreness](_URL_0_) there are basically 3 theories 1. Micro-trauma and muscle fiber breakdown from the exercise itself that hurts and then causes the muscles to rebuild stronger. 2. Lactic acid buildup that damages muscles in a delayed fashion. 3. Enzyme damage which damages muscles in a delayed fashion.
However 1. Things that are injured usually hurt right away. 2. This doesn’t happen. 3. This isn’t proven.
Basically we don’t know. | 1041b5ed-c8c4-42b7-9dac-f488c29c60a4 |
c64cqm | What are shepherd tones ? | Shepard tone: sound loop made by a series of multiple sine waves rising one after another, eventually one of them reaches a point where it drops an octave, leaving the others to continue rising, they then follow the same pattern (drop an octave, rise again), creating the illusion of a never ending pitch increase. Pretty neat trick. | 529734c0-74ee-4e05-80dc-bea8c4f83c24 |
c64p9c | Why is it common amongst animals to give multiple births but not in humans? | Basically quantity vs quality. Animals that give birth to multiple babies because more babies means a better chance that some will live to reproduce while animals, like humans, tend to be much more involved in the growth of the child ensuring they live on to reproduce e through care and protection. | db6bc3cb-90c8-45fb-a016-f122dce123fd |
c64xkv | How does that toy spin left, after I spin it right by itself? | It think these toys are made in such a way that it will spin smoothly in one direction and wobble when spun in the other direction. So, it was made to spin in one direction only. When you spin it in the ‘wrong’ direction the toy wobbles side to side and more surface area of the toy touches the desk the toy is on. This causes the toy to slow down the wrong side rotation. Once the toy is slowed down to a pause, the energy of the wobbling causes the right side rotation. You can see the bottom has kind of an irregular shape from the light reflecting off the bottom. | dacc1199-c210-4e21-bb9d-c8ad22a02469 |
c64zh5 | why does your skin make lumps when your come into contact with something your allergic too and what is it trying to do? | What you're describing is hives, or urticaria. Come into contact with an allergen > histamine is released under the surface of the skin > inflammation and fluid accumulate under the skin > said "lumps" form.
As far as what it's trying to do.. the intention of the histamine release is to help the body deal with the irritation the allergen is causing. Kind of like by acting as a messenger. Funnily enough, the histamine released actually causes allergic symptoms, and as I'm sure you're aware, can be deadly if the allergy is severe enough. | 80c713c8-a626-4de8-8063-ad29a8e7e0d6 |
c658o8 | Why are prices/value in developed countries (US, almost Europe, Qatar etc) higher than other places? | In simple terms it's simply what you can afford. They're not going to charge $5 for something when that's the weekly wage.
The price difference varies I a single country too, take the UK for example, go up north and a Mcdonalds meal is cheaper than places down south. This is also the same for fuel prices. | e4ad8dde-8a14-4bf2-bdf8-bd78b2650a64 |
c65bbr | Why do humans live longer than most other species on earth? | Interesting trivia related to this. Almost all mammals get about 1 billion heart beats per lifetime, humans excluded (we get 2-2.5 billion.)
_URL_2_
_URL_1_
_URL_0_
> Among mammals, there is an inverse semilogarithmic relation between heart rate and life expectancy. The product of these variables, namely, the number of heart beats/lifetime, should provide a mathematical expression that defines for each species a predetermined number of heart beats in a lifetime....These data yield a mean value of 10 x 10(8) heart beats/lifetime | 371b794b-237c-4e65-85cd-5f67649ad6f7 |
c65lpc | How do those electronic scales work that calculate your body fat percentage, water weight etc as well as your weight? | Fat, water, muscle, etc all have different levels electronic resistance. These scales send a small electronic shock (so small you can’t feel it) through the pads you stand on. This shock travels through your body and are read by the pads on the other side. Depending on how much fat/water/muscle is in your body the ending signal is changed from the original. The scale reads this change and calculates the percentages based on the change. For the weight portion, it reads that the same way as most other scales. Just pressure on the scales sensors. | d2c51da4-5e7e-4386-b84d-a1ab04307089 |
c65o92 | Why do some pills taste sweet and others taste like chemicals and gross, could they not make them all tasteless or sweet? | lots of medicines have a taste to them (fish oil, claritin, some asthma inhalers), so they cannot be made tasteless. Others have to use fillers that don't react with the primary medication, so they can't be made sweet.
Mostly, it's about the size and cost of the pill. You could dilute the taste of some pills, but they'd have to be ridiculously large.
Also, if they taste bad, little kids are less likely to eat them and poison themselves. | 6186987e-dc0c-477e-bcae-f9334bee2e7b |
c65ttx | How does a reddot/holographic sight work? | The sights significantly reduce parallax.
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By having the dot appear to be over a specific point. The light for the reticle is projected on a reflective surface that keeps the dot over a specific point no matter how it is viewed (with a small margin of error at the extreme edges).
The dot is emitted from a laser or LED emitter in the base point up into the window that the user looks at.
A red dot is zeroed with height and windage controls like any other kind of sight. It will always stay where you put it, but that spot in the window needs to be calibrated to a desired distance for the make/model/ammunition of gun you are using.
In practice, most dots are 2-3 MOA wide, meaning that if a target appears to be in the center of the dot, even with shifting to the side and invoking some parallax the shot will still be on target.
With a functionally parallax free single point, the dot does not need to be aligned with a second aiming point as you would do with old fashioned iron sights. Instead it stays on the target no matter from how it is viewed.
Unlike a traditional gun scope, the window in a red dot doesn’t have a magnification lens, this means that there is no specific distance from behind it that you need to be for it to be clear. Traditional scopes are not parallax reduced either, and for maximum accuracy require the shooter’s eye to also be centered in addition to being at the correct distance.
Because red dots have no eye relief distance you can also optionally magnified them by putting a magnifier behind the the red dot. Functionally turning it into a magnified scope. Less precise than a proper scope for a variety of reasons, but still an interesting application that can extend the functional range. | 2053eefb-2657-483f-8866-4994a7f19e53 |
c65zs7 | What makes a vehicle a PZEV (partial zero emissions vehicle)? | It's actually an administrative category that got turned into a kind of cringy marketing term.
PZEVs are a kind of weird netherworld of varying powertrains, including hybrids and alternative-fuel vehicles. In particular, they represent vehicles that may be net carbon-neutral, but which emit other compounds (e.g. so, for a car fueled on biodiesel, they'd be net carbon neutral, but would also generate and emit NOx to the atmosphere). PZEVs end up qualifying for some zero emission vehicle credits, which is important because an automaker has to get a certain number of ZEV credits in order to actually continue selling their vehicles in a given state.
Whoever decided to roll it into the branding of the vehicles, though...bad idea, given the seemingly obvious contradiction in terms. | 9e8140ec-e1fa-47a4-905f-a6e3ccaaef2d |
c660i4 | If we have the ability to cultivate and grow our own food as well as being able to create it in laboratories, why is world hunger still a problem? | There is enough food right now to feed everyone in the world.
Hunger is a local issue caused primarily by distribution problems, and the main cause of these problems is local disorder, such as wars and bad government. | 58366662-b17a-4a0c-ac1a-a5cd878f6a48 |
c664ov | why do animals like birds and chicken have twitchy head movements but humans can move theirs smoothly? | [Actually birds can certainly keep their heads very smooth](_URL_0_). Much smoother than humans I'd say. Their eyes dont move so they rely on the position of their heads to maintain a clear picture. | aa65ec5c-7017-426d-a4b0-515b04c469b0 |
c668q7 | During the Emergency Broadcast Systems "This is only a test" that we all hear on our tv's and radios from time to time, is there an actual purpose for those loud, buzzing tones? | Yes, to get your attention. They are distinct and annoying so will be more easily noticed if you weren't already paying attention to the broadcast. | a70286f0-2174-446b-9f52-f5153cb8b975 |
c66cys | why can you not get the same cold/virus twice, how are antibodies so powerful? | What we see as "being sick" is often the body's way of getting rid of diseases. This is part of our innate immune system, but it doesn't always work so well.
Once your body makes antibodies, that's part of the adaptive immune system. The antibodies "tag" the virus so that killer T-cells can get rid of them. So instead of trying to flush it out (runny nose etc.) or make it uncomfortably hot (fever), the adaptive immune system grabs and destroys the virus.
You could see it as the difference between having an alarm system and having someone on hand to arrest the thief. Both will stop your stuff getting stolen, but the alarm system won't stop your window being broken. | 8ba2d297-cb53-4eb5-ba9e-af5285d51c18 |
c66frt | How does moisture wicking clothing work? | As far as riding without it, everything I have underneath is polyester and I have a vented jacket. Also wear lightweight pants and lighter gloves than my normal road race level gloves. And every vent in my helmet is open.
I have a very faired bike, great in the cold but can be a pain in the heat. Windscreen down all the way and if I'm on a road trip, I carry 2 full and cold bottles of water and a large squirt bottle (It's a Gatorade brand thing I got at a sporting goods store for $3, I use them when I work out also). But that squirt bottle gets filled up with cold water at a gas station and I periodically get a drink of it from my tank bag and squirt some down my front and down the back of my neck. Quite the eye opener but helps keep me cool for 15 minutes or so. | 1593c5e4-bcdf-45d2-8b20-7b2576e62ac1 |
c66glk | When working out, is it good, bad or no impact on the result, if you get lactic acid build up? | Generally bad. Lactic acid buildup causes muscle cramping. It's usually as a result of anaerobic exercise, such as weightlifting, but it can be caused by poor condition and muscles being starved of oxygen due to the lungs not working as well as they should.
It will have a direct impact on the outcome of your exercise if you cramp, because you will have to stop sooner, and you can also physically damage the muscle tissue, preventing workouts in the immediate future. | e0bbf793-dc4b-4bbc-80cd-9eff57fa16ab |
c66gpb | about ghrelin: how did the human kind manage to develop this sort of scheduled hormone production if our ancestors were basically opportunists their whole lives and ate only when the food was around which was random and wasn't easily available back then? | Because food was easily available during human and proto-human evolutionary history. Humans were hunter-gatherers and only a few hours of searching would yield each day’s food. | 5ca98013-b8cc-4bbd-9bc4-dadfb8f1e9e8 |
c66nl0 | - Why did humanity create new languages when they migrated? If we all spoke the same language wouldn’t international communication be much easier? | It's not as though they did it consciously. Language is always in flux, the English we use now is very different from that of 100 years ago even. Of course, in the past groups in distant places would have had very little contact with each other, so language naturally diverged over time to the point where even if there was one root language in the cradle of civilization, they have since diverged to the point of being unrecognizable. | d5f3ba70-52cb-4b89-8d6c-080fdb695d13 |
c67754 | How does anxiety medication work? | Ssris aren't really for anxiety, but are prescribed for it. I'm gonna ignore them though and skip right to benzos.
So benzos or drugs in the benzodiazepine family work by increasing the output of gaba in the brain. Gaba is an inhibitory neurotransmitter so it inhibits activity in certain parts of the brain. For anxiety this is really important because anxiety is caused by unnecessary activation of the amygdala. Your amygdala keeps you safe, but it was designed for a world with many more dangers than the world we live in so sometimes it's working more than it should. When it's slowed down because of gaba it's less likely to trigger a fear response that would in turn trigger the hypothalamus into a fight or flight response which is basically an anxiety attack. That's about as much as you can say about it without getting into the more sciencey chemicals and reactions and stuff. | 7bce26ab-ba85-4cde-adac-c6b96f94c01e |
c67esw | why is gasoline prevalent on lighter engines (cars, motorcycles) while thicker fuel is prevalent in bigger and heavier engines (trucks, ships)? | Because in compounds, energy is stored in the bonds between atoms. In carbon chain fuels, the lighter the fuel, the less the amount of carbons are in one molecule of the fuel. This means that less energy can be gained from only seven bonds being broken for example when the fuel is ignited. The thicker fuels have more carbons in the chain per molecule and this produce more energy when ignited, to power a bigger engine or a bigger vehicle with less amount of fuel. To gain the same energy using a lighter fuel, they may need four times the amount. | fc677063-c904-4469-8470-ca327ad61bd3 |
c67oar | How do you 'debug' an apartment building? | Figuring out why a structure fails is a combination of reverse engineering and experience with other buildings in similar situations.
When a building is made, it isn't just thrown together haphazardly, but fully designed - so all of the elements of the structure will have been specifically designed to do certain things. By looking at how the structure is failing, and what elements of the structure should be resisting that failure, we can figure out what has gone wrong.
As a simple example, if you have a masonry house and see cracking in one corner - we know that masonry doesn't bend, so when it cracks that means something has moved. One common problem would be settlement of the ground supporting it, so if there is cracking only in one location, we could look there for causes of movement - a leaking gutter or drain could cause the soil below to be washed away or weakened, or a tree or large plant nearby (or where one has been recently removed) may cause roots to affect the structure.
If the cracking was just over one lintol, we might consider that lintol having failed and deflected - so we would look for rot or damage, or where the loading has changed (such as removing a load bearing partition inside changing how the structure is held up).
Big concrete buildings are considered in a similar fashion - by considering what the problem is, the position, shape or size of cracks, we can determine which elements of the underlaying structure would be likely to have caused this pattern of problems, and then consider ways to fix this.
It is also worth remembering that most construction is logically done, and will also follow standard guidance that is in place to ensure buildings are safe, so while every building may be slightly different, most share a set of common features and design elements. | 8c06357e-ff03-4a9e-892b-512bee36e6f3 |
c67tpx | What are imaginary numbers and what are they used for? | Squaring a number means taking a number and multiplying it by itself. So two squared would be 2\*2 = 4
The reverse of this is to take the square root, When you take the square root of a number, you're asking: "What number can I multiply with itself to get this solution?" So if I ask for the square root of 4, I'm asking what number can I multiply by itself to get 4. Which as we saw is 2.
What happens if we toss negative numbers into the mix?
Well, a negative times a negative is a positive (for reasons not discussed here) so (-2)\*(-2) is also 4. This means the square root of 4 has *two* answers, 2 or -2 (though usually we default to the positive answer).
But what if I ask about the square root of a negative number? Like, the square root of -4?
Well, we want a number, multiplied by itself equals -4. But it can't be any positive number, because a positive times a positive is a positive. It can't be any negative number, because a negative times a negative is also a positive. No number times itself can equal a negative!
We might think this is the end of line, but it turns out the square roots of negative numbers exist and can be used! When we were looking for solutions to certain kinds of math problems, they involved using the square roots of negative numbers. These square roots eventually cancelled out in the end, but it was clear that getting from point A to point B required using them.
Eventually, we codified them and labeled them. They were called "imaginary" in a derogatory sense and unfortunately that label stuck, because they are no more or less "real" than any other number.
The most fundamental imaginary number is *i* which is defined as the square root of -1. All other imaginary numbers can be represented as some multiple of *i* such as 2*i* or -4.5*i.*
Mathematically they are used any time you need the square root of a negative number. They can also be used in various types of engineering fields to represent electric currents and signals in convenient ways. | 2ce8803c-ffdb-49d8-9b99-9633efd7634c |
c67xa2 | Why does it look like other planets get hit by meteors/asteroids a lot more than Earth? | The Earth and Titan are the only planetoid with a significant atmosphere. The reason is that most of them are either too light to keep an atmosphere, or doesn't have a magnetosphere to protect the atmosphere from solar radiation. The Atmosphere will create friction with any asteroid which gonna decrease their size. So only the larger asteroid can reach the ground and of course those are rarer. That said each year on average an meteorite the size of a car hit the earth.
& #x200B;
In addition, the Earth surface move enough that most of the impact become hidden over time, and this doesn't happen as much on other planet, so we can see impact that are much older on those planet. On Earth you have water that can hide an impact, erosion from water and wind that make the impact crater smaller or less apparent, you have flora that can cover it, you have tectonic plates or volcano that can remake the surface or cover an impact. | 135e7949-e714-46e8-b870-a1a364212851 |
c685ac | Why is syrup sticky? | Syrup is essentially comprised of a mixture of two molecules: water and sugar. Both water and sugar (sucrose) are polar molecules - that is, their molecular structure is such that they have both a "positive" and and "negative" end, like a magnet.
For example, in school you may have done an experiment where you hold a statically-charged rod close to a running faucet, and it "bent" the flow of water towards it. This is evidence of the polarity of water, as it will be attracted to the static buildup in the rod.
Now, this polar structure makes these things sticky. Water has a relatively low viscosity, so it's molecules flow pretty quickly past one another in a liquid state. Water will stick to your hand, but other water molecules will slide easily off so it's pretty easy to wipe away with a towel. Sucrose/sugar is solid at room temperature, so at any one time only a few of the individual molecules can "attach" themselves to another surface at one time.
However, when you combine sugar and water together, the sugar molecules begin to attach to some of the water molecules, dissolving into the water. Add more sugar and eventually you'll get to a point where *some* of the sugar molecules attach to other sugar molecules as well as the water. This is when sugar-water begins to become more like syrup.
Now, you have a relatively viscous liquid with lots of exposed polar molecules that can stick to other things (like your hands). This is the main reason why syrup is so sticky. | 8087e46f-00a2-45af-aa4e-4de60c3da111 |
c68an2 | Sometimes when we look at a clock, the second hand looks like it just went backwards and then move forwards again. | It's called saccadic masking. Basically, your eyes go blind throughout the day and you don't even know about it.
This guy explains it better than I can: _URL_0_ | c2cf94eb-5fa9-4b3f-ad33-e805bf92d7e3 |
c68d9q | Why does a little pee fall out only once you've done your pants back up? No matter how long you wait, wiggle or dance? | Your urethra has a little U-bend in it near the base. Try putting a finger down around the back of your testicles and your thumb over the top of the base of your dick and gently pull it forward. It will straighten out the U-bend getting the excess urine out. You'll probably still dribble urine in your pants because fuck you that's why. I hate it. I've tried shaking my dick off before and there was still urine in there. Also sitting down helps. | 76f3dd1d-bff8-40c7-9ee6-08b0808a2f5c |
c68hrl | How hot can you drink? | Two answers for two questions.
Question A: What’s the hottest liquid temperature that a human could consume without hurting themselves?
Answer A: About 104-122 degrees Fahrenheit (AKA 40-50 degrees Celsius). At around 47 degrees Celsius, you’ll feel it, though.
Question B: What would happen if a human drank a liquid hotter than 122 degrees Fahrenheit/50 degrees Celsius?
Answer B: You’ll damage the interior tissue of wherever the drink came in contact (so the mouth, throat, food passage, and stomach). | d992cfe2-c074-4433-bfc3-a356758b78d2 |
c68j5i | Why does the color black go with everything? Is there a scientific or color-theory explanation for this or....??? | Black is considered a neutral color. Grays, whites, browns and blacks are neutral and tend to go with most colors. Typically certain neutral values look best with either corresponding or completely opposed values, but since black is just one value, it can go with everything. | bb0de504-03fe-48e7-b8e2-b71b3dcdc727 |
c68n40 | how are seashells formed | They are made by animals. For certain animals, the shell is literally a part of their body. They make it by the same biological processes that you make flesh and bone, and other parts of your body... which is to say, the animal basically just does nothing but stays alive, and the shell grows as they grow. | f4adfb31-97e8-489d-871c-2acf7fef0e0b |
c68qwn | Why do all the other rocky planets in photos look covered in craters from meteors, yet earth doesn’t seem to have any? | Thinner or lack of atmosphere and no precipitation/flowing water on their surface.
First, anything that is smaller than one of those Extinction event asteroids that are larger than a bus burns up in our atmosphere. There are several factors (size, speed etc.), but to generalize. Anyways, most of the meteors that hit Earth burn up/explode harmlessly in our atmosphere and don't make it to earth to _make_ a big crater.
Second, water precipitation and erosion. There ARE lots of asteroid craters on earth, but where there's sufficient rainfall, the natural course of erosion has worn down the crater walls and filled in the rest. [That one in Quebec is a good example.](_URL_0_).. imagine how big that impact must have been. | f8e597fd-a19b-4954-b5c9-9313313dc739 |
c69kpv | How the poison in/on an animal doesn't harm the animal itself? | It's not usually located in a place that can be damaged by the poison. Humans are the same way, we have germs and other things in our digestive system that if they made it back up to our stomachs, we would be seriously ill. But our bodies are designed to keep things separated.
& #x200B;
That's why getting stabbed or shot can be extra dangerous if certain organs are punctured....things start to spill into places they really shouldn't be. | 7a1fab75-7603-44d9-9ce2-73b435f9a8f6 |
c69zb3 | What happens neurologically when dominant hand is switched? | So... The science isn't 100% clear on this one, but the short answer is that handedness is a habit, just like driving or typing. If suddenly your keyboard gets rearranged, you'll feel really weird using it until you eventually get used to it. Neurologically? I'm not sure what you mean. Your brain doesn't flip backwards or anything. You just get used to living a slightly different way, and establish different habits. | f0e42fdc-0b39-4afe-bb29-079513867d3d |
c6arj8 | why are solar-powered cars not a thing? think of the battery recharge on a sunny day sitting in rush hour! | There is not enough energy in the sunlight to make that efficetn
Sunlight is around 1000W/m\^2 but solar panes have around 20% efficenecy so around 200W/m\^2 in full sunlight tilted toward the sun.
A Tesla model 3 is 1.9mx4.6m so it cover a area of 8.7 m\^2 but lest say it is 10m\^2. So you would get around 2000W= 2kW of power from the solar panels.
The batteries of the model is 50,62 or 75 kWh so it would take between 25 hours and 37 hours to charge the batteries.
The range of the batteries is 220 miles (354 km) for the 50kWh and 325 miles (523 km) for the 75kWh
If you assume that it is at 90km/h (55mhp) you can drive for 4h or 6h but the recharge time is 25h and 37h. So in the ideal case for sunlight the solar panel would provide 4/25=0.16 that is 16% of the power you need.
So you can power a regular electrical car by the sun even in max sunlight condition with tilting solar panels with the same area as the car. It practice they panes will be tilted towards the sun and you get less power. In low sunlight condition the extra mass of the solar cell will decrease the range of the car.
Building solar panel that cover the whole car would be increase the cost of the car and the weight and power use for the car so it is in general not a good idea.
Is is a lot more cost efficient to install fixed solar power on buildings and use them to charge a battery that you can charge the car with when you are home.
There are prototype design this [like this](_URL_0_) that provide 12km of range per hour in the sun. So you can do that but they are expensive and the the more economical option is solar panel on the house and a battery
You can build [Solar\_car](_URL_1_) that only use the sunlight but the are not like regular cars because you need to keep the mass and the drag down. So that do not provide enough energy for a car for everyday usage. | 659d3517-d679-46d4-bb87-9c65472b4471 |
c6atan | How do languages in the same "family" split off from one another? | There are a few things at play: physical distance, new people learning a language and dropping more complicated elements, interaction with other nearby languages, and a corollary to that last point, takeover of an area by an outside force.
Modern English, of the Germanic family, has had a lot of contact with Romance languages of western Europe, most notably French. This is thanks to the Norman conquest of England in the 11th Century. During this time frame, Anglo-Norman, a dialect of Old French influenced by Old Norse, became the language of the English ruling class. Many of these words entered the English language used by the populace, and today, despite its Germanic Heritage, about 50-60% of the total words are derived from Romance languages - either French or Latin. (This does include medical/scientific/legal terms). | 01d25510-e34b-4cd5-adb5-c260cc5c668c |
c6auqt | What are the practical implications of a city or country declaring a “climate emergency”? | Emergency declarations allow some procedural steps (it varies wildly) to be skipped, primary with funding and resource allocations, to face an emergency.
If there was, say a tornado in a town, a town could declare an emergency to be able to have more money on hand to keep first responders working without worrying about pay budgeting.
For a climate emergency, it could yield money or speed up approval of projects and programs. It additionally could allow a municipality to expand their regulatory powers. Such as how a water usage restrictions can be imposed during a drought/wildfire emergency.
The downside is that it reduces oversight and accountability, particularly from legislative bodies. | ed48c9b7-5406-4d7f-afdc-3d0b02086ccb |
c6avcf | How do vinyl records play music? Like how does a needle spinning on grooves give off a specific lyric or song? | A sound is a vibration. If you can vibrate the air exactly the same way, it sounds the same.
& #x200B;
Your vocal chords are vibrating the air that passes over them when you speak. Now take a speaker on a stereo. If it vibrates using the exact same measurements as your vocal chords, it can replay exactly what you said in your voice.
& #x200B;
The needle is spinning on grooves that make it vibrate. those vibrations are amplified so we can hear them. | a68e5256-2fe1-401d-9e4b-3dadb0ea6d00 |
c6b35i | Why does a popcorn pop while others corn do not? | Popcorn is harder than other corn kernels. The outside keeps water from escaping, causing kernels to explode. Other grains like sorghum and quinoa will pop though! | eb64cf15-2a05-45cb-86dc-723b1391183c |
c6b99i | Why are there “acquired tastes”? Why do some things, like beer, whiskey, and food delicacies take a few tries to become palatable? | These are my observations. It might be different for different people, and for different foods or beverages, but in general you can just get used to anything.
Sometimes it also just takes a little while to get over the initial shock of an exotic taste that might be unpalatable or even painful, like in very sour or spicy foods.
The tastes of people changes over time and as they grow, which can also lead to developing appreciations for things you didn't like before incidentally, not directly. | e2c97200-ab7a-4ec4-b39f-1caa90e94e08 |
c6b9un | Why is is that sometimes we'll say a word so much it starts to not sound like a word anymore? | Anything can start to sound like gibberish if you say it enough. The redundancy of saying the same sort of consonants, vowels, syllables begins to twist our tongues.
And that is the birth of tongue twisters!
She sells seashells down by the seashore | 4fd68ef5-829b-470c-b3fd-e74395292c55 |
c6biha | How can manure/hay self combust in hot temperatures even though they're nowhere near 200+ degrees celsius? | hay is more than just dried grass... it’s actually undergone a natural curing process which locks in nutrients and makes it keep better. This happens because grass doesn’t die the moment it’s been mowed...its cells (and certain microbes on it) continue to respire, and this creates some heat.
now imagine this grass is a little bit damp... it gets made into hay bales and theyre stacked sky-high in a sealed barn. the middle of each bale has little chance to cool down (low air flow) and the cellular respiration... and maybe even now some fermentation... go on and on. this is like having a pile of oily rags in a hot room. the temperature inside the bale can climb to the tipping point where it starts smoldering. nobody notices. it’s packed can’t-reach-it deep in a barn full of fuel. ay yi yi. | cdbec53f-99f9-4f83-ac9a-8e1ddb3f2da3 |
c6bowu | how does cancer kill? | 3 ways (predominantly):
1. The cancer cells themselves: cancer cells (malignant ones) are incredibly resource-intensive. The worst parasite you can imagine. They gobble up all your body’s nutrients (i.e. glucose - which is actually how a PET scan detects cancer, by seeing which cells are “eating” the most glucose). There’s no way you can keep up; you’re literally being starved from the inside out. Couple that with metastatic cancer (when pieces break off and latch somewhere else), and you’ve got multiple parasitic growths. And boy do they grow. So even if you cut out one of the tumors, they’ve already seeded elsewhere.
2. The cancer cells as a “mass”: most evident for solid tumors, not only are they eating your resources, but their growth will invade nearby tissues. A big enough lung cancer will grow into your trachea, and you die. A big enough colon cancer will perforate your bowel. And you die. Really sad story of a patient who has a cancer of the neck, wrapping around the carotid artery; inoperable (ie the operation would kill them), and it’s just slowly growing. One day, without warning, the cancer growth will rupture the carotid artery. And...you get the picture.
3. Leukemia/lymphoma as immunosuppressants: cancers of the blood especially put patients at risk of immunosuppression - that is, only mutated, cloned and non-functioning immune cells are created. The patient is basically left with a very weak immune system, leaving them vulnerable to some quite dangerous bacteria, viruses and fungi that we would otherwise be able to fight off but can in themselves bring about the demise of a patient
Bonus way: cancer cells are incredibly thombophillic (“pertaining to the love of clots”), meaning they can create blood clots that shoot off into your lungs or heart. And you die. | e921bb8e-83a1-40fd-a99d-f29b33f7c4ce |
c6bppr | what constitutes how "full" you feel? | There are actually a number of different hormones and enzymes that affect satiety. These are released and picked up by the nervous system, causing your brain to cease the feeling of hunger. Release of these hormones/enzymes happens following physical stretching of the stomach, when certain pH levels are reached, etc. | 5bb98d55-d799-46e5-a37c-6928813a4361 |
c6bwz8 | Why do baby deer have spots, but adult deer don’t? | Baby deer are left alone while their mothers find food. The spots on their back help them blend in and stay safe from predators because from a distance the spots look like sunlight filtered through trees. | 43600541-81c2-4225-9165-c0b2fdebe9f5 |
c6byr0 | Why do flies keep trying to sit on you when you swat at them and don't see you as a threat like most animals would? | I flies brain is very small. Think of it like a video game A.I. the fly has default reactions to any given sensory input and can and will repeat its actions over and over until different sensory readings cause a different sequence of actions. Flies sense things like chemicals/moisture emitted from your body as well as motion, like your hand coming to swat. They have set actions programmed into their simple brains to react to such inputs. Their brain tells them to fly towards moisture and fly away from motion. However those commands never changed so they will fly back towards moisture/chemicals over and over again | fcae6d01-e384-46a4-b34b-7e0d22a0aefa |
c6c12m | Is it just a coincidence that maps and globes wernt originally drawn upside down? Why is North considered up? | The explanation it that is is easier to draw for the northern hemisphere if north is up and the today dominant map making tradition is the one from Europe and in some ways start with [Ptolemy](_URL_0_) On the northern hemisphere you can see that we rotate around a point in the north and if you then draw a map of what was known to be a globe it works better if the point of rotation is up.
Ptolemy used a coordinate system with latitude and longitude and create a map like [This](_URL_0_#/media/File:PtolemyWorldMap.jpg) where you can see that the latitude merge to a single point and you can dra the with a fixed there.
& #x200B;
Globes have north up because the was first made in Europe and people like to see where they live as easy as possible. Most people still live on the northern hemisphere so most globes is made that way.
Most exploration to map the work was done by European countries so that keep that north is up maps. | 18d49d60-7acc-4beb-b5d2-aa1a41aaa45e |
c6c914 | Why do you have to refrigerate eggs from the grocery store but you don't have to if you get them fresh from a farm? | There is a membrane that comes out of the chickens that cover the egg. In the US, its standard to have the manufacture plant wash and sanitize them, but in places like the UK, they don’t so they can leave their eggs on the counter or shelf for a while. | fb59ef39-6e97-4b4f-aa40-84248f2e288a |
c6ckbv | How do birds know how to build a nest? Do their parents teach them or do they just watch fellow birds and copy them? | Instincts, it’s beaded into their genetic code that they have to have a shelter and they build one out of whatever is available, some are different based on species like how some birds find hollows and others make nests. | 08652060-fb78-4b14-a51b-4af31cd0ad28 |
c6cy25 | Why an opt out tax for socially divisive services like planned parenthood is a bad idea. | I’m no politician but I’m guessing enough people would opt out simply to save money that programs like planned parenthood would not have the funding necessary to continue operations. | e3f71c37-161b-44dd-801a-df4bbc09c550 |
c6cz0i | Why do gyroscopes remain upright, instead of falling or twisting in the direction of the spin of their gyro wheel? | Gyros do not, strictly, stay upright. I'll give you an answer that sort of makes sense, but it will not be perfect by any stretch. If you imagine pushing on one side of a gyroscope, you're pushing on one part of the disk. Now that you've pushed it down, that side of the disk is going to move down a little bit. However, it is still also moving sideways, so it isn't under your finger anymore. Now, you're pushing a different part of the disk - one that you haven't pushed before - so it hasn't moved down yet because it hasn't been pushed yet. This all means that the wheel doesn't actually have a chance to move all the way down until it has rotated way past your finger - one quarter of a rotation of the wheel, to be exact. This means that when you push on the wheel, it actually rotates in a different direction that the direction you pushed.
Now, for why a spinning gyro doesn't fall down:
Gravity is trying to pull the gyroscope down. It has to rotate in order to fall down. But it rotates in a different direction because of what I told you before. This means that instead of falling down, it slowly rotates in circles. You can watch a gyroscope spin for a while to see what I mean. | 7494cef8-d0de-4994-a91e-0fdf0c2b95af |
c6d7tq | Why does water get 'stale' after leaving it out for a while? | Water has a lot of other molecules inside it besides H20. Water is also a good solvent for gases like carbon dioxide which is absorbed thru the air. When the cardon dioxide mixes with the H20 it forms something called carbonic acid. Which will lower the pH level of the water giving a slightly musty taste.
Temperature can be another factor. If you poured the water while it was cold or had ice cubes in it, coldness acts as a flavor supressor due to the molucules moving at a slower pace. Once it warms up you can taste all the little impurities inside it. | 44d2153d-d974-4179-99b6-7a6ad83cff69 |
c6dd6k | Do bugs know/care if we transport them far away? | Flies and ladybugs probably don’t care as long as they can get food.
Ants, bees and wasps that have somewhere to go home to at night... they definitely care.
Some spiders are territorial, and would care a bit, others are opportunists.
Beetles and sow bugs? No idea. | 202fb9be-abd9-47c9-92c5-017d1075a799 |
c6deel | Why does 75 degree water feel a lot colder than 75 degree air. | The temperature we “feel” has to do with how quickly the heat is conducted away from the surface of our skin. We normally have an envelope of warm air around our body, so that protects us from temperature variations in the air. When we step into the water, we instantly lose that protective layer of air, so we feel colder as the water conducts away our body heat. | 7876693a-23e9-4693-af9c-f28f62cce5bd |
c6dpg9 | How do growth spurts actually work, and why does such a drastic jump in height/size not happen at any other point during human development? | The surge in hormones during adolescence affects the brain as well as the body. In adolescence, growth spurts prepare people for reproduction, like by making female bodies better able to support a baby, etc. And male bodies stronger probably for evolutionary hunter purposes.
Babies develop even faster for their first few years | 56658662-640f-4981-9025-f2f27b2a3dec |
c6e6qc | Why do some credit card machines require you to remove your card quickly then decline your card if you’re not quick enough? | Because it is the act of moving the magnetic stripe past the reader that allows it to be read. The mag stripe is made of magnetized particles, with the orientations in different directions. The act of moving the "tiny magnets" past the read head induces a current in the head which allows it to be detected. The faster the movement, the higher the current. If you move it too slowly, the data can't always be read reliably and there are too many read errors for correction. | 5cd9e37f-4c7b-41d8-a315-3500dad298fc |
c6e99q | What is the 'Frostbite' engine in gaming and what does it do? | Ok, so Toyota designs a car and the spend most of the time working on the internals. They make a frame, engine, and a transmission. All the internals that make a car go. One of the last things they do is the body style and interior. The cosmetics if you will. They will change the body style and interior each year but the main working parts will stay the same. That way for all the research and engineering they do they can have that car for 5-10 years, maybe more.
& #x200B;
Well video game companies do the same thing. They design an engine. EA has Frostbite but there are others. Unreal and Source are others. They make them solely to handle physics in game as well such as Havok. These companies put a lot of time and effort into that engine and therefore they use that engine as often as they can and license that engine to other companies. Companies than build their games using those engines. The engine contains most of the core of the game. Think of it as an engine/transmission/frame of a vehicle. So now you as a game developer can use that and build your game around that adding your cosmetics and mechanics without having to code the other things. You can modify this engine to suit your needs within reason but most of it you won't do much to.
& #x200B;
The really popular and well done engines tend to be bragging rights and companies want to broadcast what engine they are using. Car companies do the same thing. You know what a Hemi is right? Thats a type of engine. When you see a truck or car with a hemi badge you think certain things. EA does the same thing with Frostbite. | c586565f-3065-4b3b-b090-e6634745f145 |
c6e9ps | Why are black Americans so much more prevalent in the news and in pop culture, compared to Latino Americans, the largest minority in USA? | The ways latinos are portrayed in tv and movies are really cringe worthy so the less the better. However if you want to see more latinos watch the Marvel shows on Netflix, there's plenty. | c49220fd-fa54-4f8d-b84e-fc66cfc1fa21 |
c6edz9 | Can you heat an object until it turns blue? | The color of a flame is not always indicative of its temperature. The color is indicative of the chemical composition as well as the temperature. If you heat a piece of metal with a blue flame, it won't glow blue. That's because its glow is due to what's called black body radiation. A black body is an ideal opaque, non-reflective body. All things emit black body radiation, even very cold objects. The black body spectrum has a peak near its shortest wavelength, and a long tail reaching into radio spectrum. As the temperature rises, its peak wavelength eventually reaches infrared, red, orange, yellow, green and blue. Why don't we see green and blue? Because when something is hot enough to emit green or blue light, it is also emitting yellow, orange, and red. Those colors mix and the hottest color we see from a black body is a bluish white no matter how hot it gets. See the [Planckian locus](_URL_0_) | e2817b4e-dcab-4612-8200-dc09e81ea5b0 |
c6efdi | What determines the (often very high) cost of medical procedures and technology, and how do countries that cover that cost afford it? | Countries that cover it don’t hike up the prices many many times over the actual cost. They most likely pay fair market value for supplies, and pay the people involved their direct salary
In the US, hospitals can charge nearly anything they want to, and insurance companies often do not pay full value either. Medicaid, which is a federal insurance program for many people in poverty, isn’t even accepted by many private practices for this very reason. The doctor would only be paid the actual cost of the procedure, which would cover IT, but not a new boat. | 69b280ac-d659-4252-a771-f508a73a2519 |
c6eg2c | Why do medications for mood/depression (Zoloft, Celexa, etc) take weeks to "kick in"? | We don't actually know for sure why that happens. Its kinda annoying. But for SSRIs like the ones you mentoned, the most recent research suggests that the chemicals don't bind directly to the serotonin transporter. Instead it binds to DNA, slowing the creation of new serotonin transporters.
You already have a whole bunch of them stored in your brain when you start taking the medicine, and you have to keep taking the medicine as the amount goes down. This process takes a few weeks, and if you stop using the SSRIs before then it just goes back to producing the normal amounts again, and the depression continues. | 14ae5e59-2c11-485c-8675-f13e281222d1 |
c6eg2d | The Thammasat University Massacre | Like you’re actually 5?
From what I remember learning;
All the kids decided they didn’t like the principal so they got together and showed how unhappy they were.
Supposedly some of the kids put on a play about the principal being killed.
Principal got very mad and used his forces to kill like 60 people and wound over a thousand | de207efd-7b2b-47e6-95d7-43e2e2e9eef5 |
c6ejlf | Why do different kinds of alcohol make you feel different kinds of drunk? Or make you feel a different kind of hungover? | Alcohol is alcohol. There's no proof that there's any real difference, meaning it's most likely just all in our heads. | 49c2cba6-2945-4f07-a980-f8cecd63d66d |
c6evii | Why is the current weather in Europe much more dangerous (at least as reported in the news) compared to other locations at similar latitudes? | Because air conditioning is not common in many parts of Europe, and people are not used to the hot weather. It is especially stressful for people who are old or sick. | cd9da8fa-efae-4033-912d-560786976e6f |
c6ew85 | why would the death penalty cost more per year than a system of life (in prison) without possibility of parole? | When we sentence someone to death, we have to house them in a maximum security wing, basically solitary confinement but with some privileges like visitation, while they await trial. That trial can take a long time, compared to other crimes, because there is a higher burden to get it right.
They then get automatic appeals, starting in the state courts and going into US district courts, all the way up to the Supreme Court, depending on the specifics.
Then they have to wait their turn to be executed, with delays coming in the form of running out of execution drugs, new evidence or circumstances coming up, or other issues.
And every time they go to court, there is extra costs on transporting and guarding back and forth from the prison, which can last days or weeks at a time, every day.
With a life sentence, the automatic appeals are out the window. They can only appeal if they have new evidence. They don't necessarily need to be segregated from the general prison population. They don't need to go to the courthouse every day for a few weeks twice a year. | a0ebe0e8-2162-400a-b713-5b8a45068926 |
c6f2nw | How do drinks stay carbonated? Why doesn’t carbonation just bubble to the surface and leave water the way air does? | Carbonating drinks is actually adding carbonic acid to water. This substance is unstable in normal conditions and tend to split into water and CO2, the latter is chemically inert and safe for us. But being under pressure and dissolved in water carbonic acid stays well acid. So we have a closed bottle of carbonated drink where carbonic acid started to excret CO2, which rises pressure, which stops decomposition of the acid. When we open a bottle, pressure drops and we have nice bubbles. | 3cbff254-729e-4023-93bb-2f18ff602864 |
c6f47k | how scientists counted numbers of electrons on each shell (energy level) of atom? | tl;dr : Electrons exist in predictable energy levels that we can measure by seeing how much energy it takes to remove each of those electrons (ionisation energies) and graphing it.
& #x200B;
This is a great question! and unfortunately requires a long answer in order to fully explain it, Id argue this is more of a chemistry related question, so I'll answer it as if im a chemist:
& #x200B;
Ionisation energy is the energy required to remove one electron from one mole of gaseous atoms. The first ionisation energy is the energy required to remove the valance (last electron) in the outer shell from one mole of gaseous atoms. (here is a graph showing the first ionisation energy for each element)\[[_URL_1_](_URL_1_)\] and from this we can already start to see a pattern.
& #x200B;
There are multiple factors that affect the ionisation energy
1. **Size of the atom:** The bigger the atom, the further away the valence electron is, and therefore less energy is required to remove that electron
2. **Nuclear charge:** The greater the charge of the nucleus, the more attracted the electrons are, and thus harder to remove and requires more energy
3. **Shielding effect:** The greater number of electrons between the nucleus and the valance electron, the weaker the attraction to the valance electron and the less energy required to remove it.
4. **Electron configuration:** This one is a little harder to explain;
& #x200B;
In school we are told: The first shell holds 2 electrons, and each consecutive shell will be able to hold up to 8 electrons. Lets take a look at a single element and discuss this further.
(A graph showing the complete ionisation of Neon)\[[_URL_0_](_URL_0_)\] Neon is a good example here, as it contains 10 electrons total and has 2 shells.
Unfortunately, its not as simple as school makes it out to be. Within shells, there are also sub shells and each sub shell contains orbitals. Neon has the electron configuration of:
1s^(2) 2s^(2) 2p^(6)
* First number being the shell number/ Energy level
* Electrons come in pairs in orbitals but with opposite spins. Electrons will half fill orbitals first, before pairing up.
* S/P being the sub-shell type. ( S holds 2 electrons= one orbital, P holds 6 electrons =3 orbitals)
* The last number being how many electrons in the overall shell
& #x200B;
Lets go back to the first graph.
First ionisation energy increases across a period. This is because the nuclear charge is increasing, but the electrons aren't moving further away from the nucleus, just increasing in number (until they fill up shells) This means these electrons are more attracted to the nucleus and require more energy to remove.
& #x200B;
**Why does lithium have a lower IE than Helium?**
& #x200B;
Lithium config: 1s^(2) 2s^(1)
Helium: 1s^(2)
\- > the valance electron in lithium is further away than the s electron in helium, so it is easier to remove.
\- > Shielding from the 1S electrons reduces the attraction of P electrons to the nucleus.
& #x200B;
!! **The big difference in energy between 1s and 2p is why we determine the first shell to only have 2 electrons.!!**
& #x200B;
**Why does nitrogen have a higher IE than Oxygen?**
& #x200B;
Nitrogen config: 1s^(2) 2s^(2) 2p^(3)
Oxygen config: 1s^(2) 2s^(2) 2p^(4)
& #x200B;
P shells fit 6 electrons, and have 3 orbitals. Nitrogen has a full shell of half filled orbitals, this is stable compared to oxygen, which has 2 half filled orbitals and one paired orbital. This paired orbital contains two electrons which are repelling each other. This repulsive force means it's easier to remove the valance electron of oxygen over nitrogen.
& #x200B;
Why does Sodium have a lower IE than Neon?
& #x200B;
Sodium config: 1s^(2) 2s^(2) 2p^(6) 3s^(1)
Neon config: 1s^(2) 2s^(2) 2p^(6)
& #x200B;
The same reason as why lithium has a lower IE than helium.
\-- > 3s is further away than 3p, reduced attraction to nucleus (nuclear charge)
\-- > Increased shielding from other shells reduces attraction
& #x200B;
**!! The big difference in energy between (2s/2p) and 3s is why we determine the second ( and consecutive) shells to have 8 electrons. !!**
& #x200B;
This pattern continues.. until you get to transition metals, that's a whole other head spin and doesn't follow these traditional rules because chemistry likes to make life difficult for us! | 50a36936-b633-44bb-a4cf-3ab6e0585158 |
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