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  • Hey, Vsauce. Michael here.

  • And today, we're going to talk about this. Just kidding.

  • We're going to talk about this. Left.

  • What's left? First of all, 90% of humans, regardless of

  • culture or language are right-handed. And we choose a dominant hand before we've

  • even left our mothers. That's right.

  • When a baby inside its mother's womb is seen sucking its thumb, it is sucking the right

  • thumb 90% of the time. Animals do it too.

  • In fact, horses take longer strides with their right legs, which is the entire reason racetracks

  • are run counterclockwise. Left-handedness is so rare that across most

  • cultures there has been a historical stigma against being left-handed.

  • In fact, the word for somehow who's good at using both hands is ambidextrous and "dexter"

  • comes from Latin for "right." So when you call somebody ambidextrous, you're

  • not saying that they're good with using both hands, you're telling them that they have

  • two right hands. And if someone is unable to use either hand,

  • they're called ambisinister, because in Latin "sinister" means "left."

  • But why do we have to have a dominant hand in the first place?

  • Why can't we all just be awesome with both hands?

  • Well the fault lies in the brain. Now, brain wants to be efficient, so it divvies

  • up tasks to specific regions and it tends to avoid sending too much information between

  • both hemispheres, because doing so would require using the corpus callosum, which would take

  • more time and energy. Now, the way the brain works is kind of funny.

  • The left side of the brain controls the right side of the body and the right side of the

  • brain controls the left side of the body. So it makes sense that the hand you're best

  • doing precise stuff with would correlate to the hemisphere of the brain that does the

  • most precise processing. In 95% of right-handed people it's the left

  • hemisphere that deals with precise language thinking, like definitions.

  • But when you're left-handed, there's about a 40% chance that you're using the right hemisphere

  • or both. And this is where things get interesting.

  • Now being left-handed or ambidextrous does not mean that your brain works in one way

  • or the other. But it may help explain why across averages

  • ambidextrous people sometimes score lower on IQ tests, or why a greater proportion of

  • schizophrenics are left-handed or ambidextrous than the rest of the population.

  • Now that said, there are giant benefits to having a brain like that.

  • By sending information back and forth, more novel connections are made, more creative

  • ideas are made. Albert Einstein was left-handed.

  • And 5 of the last 7 US presidents have been left-handed.

  • There's something else left-handed people have an advantage with - keyboards.

  • On a QWERTY keyboard, thousands and thousands of English words can be typed using the left

  • hand. But on the right side of the keyboard you

  • can only write maybe about a 100 or so. On the left side of a keyboard the left hand

  • all on its own can type pretty long somewhat common words, like stewardesses, reverberated

  • and desegregated. But on the right-hand side the longest common

  • word you can type is "lollipop." Oh look, a spacebar.

  • When people go to space, they have left Earth. The first person to leave Earth into space

  • was Yuri Gagarin, a Soviet cosmonaut. But the one I'm interested in was the fourth

  • man into space, Gherman Titov. He may have only been the fourth person into

  • space, but he was the first person to have left Earth and simultaneously left wakefulness.

  • Titov was the first person to sleep in space. And here's what's really fun.

  • He was 25 years old when he did it, which means that to this day Titov is the youngest

  • human who has ever been to space. You know what else leaves Earth?

  • Helium. That's right.

  • Helium gas that we use in balloons is lighter than air and so molecules of helium rise all

  • the way to the very tip top of our atmosphere, where they get picked off by solar wind, meaning

  • that they leave us forever. In fact, there's a little bit of a concern

  • over how much helium we have left, because the only way helium comes into existence on

  • Earth is through radioactive decay. Alpha particles are essentially helium nuclei

  • and we find a lot of helium inside natural gas.

  • But right now we're using a lot of it and helium is quite cheap, so there's a realistic

  • concern that within the next 30 or 40 years we may have no helium left.

  • Thanks for watching.

Hey, Vsauce. Michael here.


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還剩下什麼? (What's Left?)

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    林宜悉 發佈於 2021 年 01 月 14 日