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SciShow answers ten of the most asked questions by YOU, our viewers, in the past month -- from “What is new car smell?” to “What would happen if you drilled a hole through the planet?”

Watch more of the World’s Most Asked Questions here: https://www.youtube.com/playlist?list=PLsNB4peY6C6L1A74436Ccy3pvDhb33fhi

And don’t forget to subscribe to http://youtube.com/scishow
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 Intro


So Google gave us ten of the most asked questions in the world, ranging from, "What is the meaning of life?" to, "How do I get rid of hiccups?" And we here at SciShow have answered them.

But what about your most asked questions? The things that you, our audience, are curious about. We've gotten a lot of questions in the last few weeks and I'm going to answer ten of them as fast as I can.

(intro plays)

 Why do we close our eyes when sneezing? (0:30)


First, you close your eyes when you sneeze because you do. It's certainly not to keep your eyeballs from falling out of your head, a terrifying myth that we tell to children.

The sneeze response is complicated and it involves a lot of muscle contractions; for some reason your eyelids are part of those contractions. It might have some evolutionary advantage; it might just be that your face nerves are so convoluted, it's simpler for your brain to just contract everything during a sneeze.


 What is new car smell? (0:51)


New car smell comes from the slow release of volatile organic compounds used in the manufacturing of the car. These compounds include paints and lacquers and glue and leather treatments and petroleum-based materials used in upholstery, like vinyl and polyester. One sampling found over 60 different gaseous compounds in the interior of a new car. Their concentration drops by about 90% in the first 3 weeks.

 How do hairs that have a maximum length know when to stop growing? (1:11)


Next, you are one of the few animals that can grow hair in indefinitely, by which I mean there is no maximum length for the hair on your head. No wild animals have hair that grows without stopping, for obvious reasons; it gets matted and tangled and terrible. But our head hairs and the hairs of some animals that we've bred to grow more beautiful or useful hair are the only hairs that don't know when to stop.

Most follicles have a rest phase, during which hairs stop growing and the end of the hair breaks at the root. It stays attatched until the next growth phrase pushes out the hair. But our head hair just dosen't ever rest. 

 If a fizzy drink was poured in zero gravity where would the bubbles go? (1:45)


Hey, fizzy drinks and microgravity! Luckily, NASA has studied this. Check out this bubble of water eating an Alka-Seltzer tablet. Basically, the bubbles just go everywhere and push into each other, creating bigger and bigger bubbles until those bubbles break or are broken. Pretty cool!

 Why is it bad to drink cold water after exercise? (2:00)


Also on the fluid front: cold water is not bad for you. It's just maybe very slightly less good for you. Water is absorbed by your body in the large intestine. Depending on how much food you've got in you, it can take anywhere from five to one hundred minutes for it to get there. On the low end of that time scale, the water might still have some of its original temperature when it gets to your lower GI tract. At that point, if it's still quite cold, it will be absorbed slightly more slowly than it otherwise would be. But really people have made way to big of a deal about this. Do not worry about it.

 Is it even theoretically possible to transplant a brain? (2:27)


Oh, brain transplants, well, we have transplanted heads - monkey heads and dog heads - in experiments that were seen as unethical even when they were done. That's stopped. Haven't happened since the 1970s. Brain transplants are way more complicated than that because of all the complicated set of nerves and vasculature necessary to connect all the stuff together, but I'm not gonna say it's impossible. Just that it's definitely a bad idea.

 Why is hot hot? Why is cold cold? (2:50)


And why do we need sensations? Well, sensing hot and cold are useful because both of those things are dangerous. What we sense as "hot" is higher than ideal temperature, and what we sense as "cold" is lower than ideal temperature. Ideal for us, for humans. Pretty egotistical, but there you have it. As for why those feelings feel what they feel like, that's one of the great mysteries. We know why we feel the things, but we don't know why they feel the way they feel. Probably there is simply no reason.

 How and why do genetic mutations occur? (3:16)


Genetic mutations occur for a bunch of reasons, but broadly, just because your entire genome has to be copied in each of the billions of cells you create every day, and that is a lot of transcription, so every once in a while, something's gonna go wrong. Occasionally it could be caused by some solar radiation or some obnoxious chemical that got into your body somehow, but mostly it's just little accidents, and it really is remarkable that it doesn't happen more often.

 How do you get water out of your ears without jumping and tilting your head like a weirdo? (3:37)


If you've got water in your ears and you don't want to jump around like a weirdo, my suggestion to you is just jump around like a weirdo. Get over it! It's fine!

 If a hole was made going straight through the planet, what would happen if you fell in it? (3:44)


Finally, number ten! If you drilled a hole through the planet, it would immediately fill with magma, and the intense pressure placed on all that magma would cause it to shoot out both sides of the planet in two gigantic volcanoes. If you jumped in before the volcano happened, you would quickly die. If you jumped in after, you would quickly die. Either way, you wouldn't die so quickly that you wouldn't experience a great deal of pain. For a more full explanation of what would happen if you had, like, a reinforced wall around it, you can check out this collaborative video from our friends at Minute Physics and Vsauce, who are awesome.

Thanks to everyone who asked such wonderful and weird questions. You can watch more of the World's Most Asked Questions here, and don't forget to go to youtube.com/Scishow and subscribe.

[outro plays]