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  • As you probably know by now, weve been working with Google and YouTube to answer

  • ten of the most popular science questions asked on the internet.

  • And I gotta hand it to you, because there are few questions that are as confounding

  • and complex and fascinating and inspiring, as this one the collective consciousness has

  • spewed forth:

  • What is energy?

  • I'm Hank Green, and this is the World’s Most Asked Questions.

  • [Intro]

  • Energy is everything. It’s everywhere. It’s one of the true constants of the universe,

  • because as long as there’s been a universe, there’s been energy.

  • And while it comes in lots of different forms that can seem different to us, they all amount

  • to the same thing: Energy is the ability to do work.

  • And work is just the act of displacing something by applying force.

  • So, say you stomp on a stomp rocket. The force of your foot hitting the pedal is turned into

  • the force of air leaving the cannon -- sending your rocket sailing.

  • Or maybe you're enjoying a nice patty melt -- the energy from that food is broken down

  • for all of the quadrillions of cells that you have to do all of the things that they

  • have to do -- make copies of your DNA, assemble and repair proteins, transport materials from

  • one place to another, make muscle cells contract -- you know, all the stuff of being alive.

  • That rocket sailing, your cells toiling away, your phone or computer being on right now

  • to watch me -- that’s all work being done.

  • And the ability to do these things is inherent in everything around you. Even things that

  • look inert, completely lacking in energy. Like this log.

  • This log, for example, is chock full of chemical energy because it’s made up of combinations

  • of carbon and hydrogen and oxygen formed into lignin, which is the stuff that makes up wood.

  • All of the bonds between all of those atoms, in every molecule of lignin, contain energy.

  • How do I know? Because if I were to apply enough extra energy, like as heat, to break

  • those bonds -- it would release that chemical energy as fire.

  • That chemical energy also the kind of energy you get from that patty melt -- your body

  • is fueled by the chemical bond energy in sugars, fats, and proteins.

  • But this log also contains nuclear energy!

  • Each atom in this wood has a nucleus, made of protons and neutrons, and the energy that

  • binds them together is one of the most powerful sources of energy in the universe.

  • If you could split one of the atoms of carbon or hydrogen in this log, and rip those protons

  • and neutrons apart, it’d release some of that energy. There’s so much nuclear energy

  • in each atom that, if I could unleash all of it that's in this log? There’d be a giant

  • smoldering crater where I’m standing and everyone in the town of Missoula, Montana

  • would be dead.

  • So, everything that’s made of atoms has nuclear energy locked up in it, but also,

  • it turns out, that mass and energy are the same thing!

  • You might have heard of this little equation that a German patent clerk came up with about

  • a hundred years ago: E = mc2.

  • And there are SO MANY OTHER KINDS of energy that I’d love to get into if we had the

  • time ...

  • .. but even though they may seem different, they can all be used to do work, whether it’s

  • driving a turbine, or moving a engine piston, or allowing the screen on your tablet to glow.

  • Or, if it’s that most mysterious of energies, dark energy, causing the universe to expand

  • more than it seems like it should.

  • But here’s the thing to remember.

  • Once the work is done, the energy isn’t done.

  • Because energy never goes away.

  • It can never be destroyed, and in the same way, it can never be created.

  • It can only be transferred from one source to another -- like, how the energy in the

  • plants and animals that were in the patty melt were transferred into you -- or it can

  • be transferred from one form into another -- like the chemical energy in the wood being

  • transferred to light and heat as fire.

  • You could think of the universe as a constant flow of energy, and we are just little pit

  • stops along the way.

  • Everything your body is doing right now -- whether it’s your lungs absorbing oxygen, your heart

  • pumping blood, your brain cells firing as you watch me and learn things -- all those

  • things are using recycled energy that’s been around since the origin of the universe.

  • And by simply being alive, youre releasing that energy back into the environment around

  • you, to be used by other things in other ways.

  • So Internet, to answer your question: Energy is everything.

  • And for those of you who answered our questions on our SciShow survey, where you feel like

  • you get your energy may be keeping you up at night. Survey takers who have a hard time

  • falling asleep nearly every night get their energy from knowledge first, second from purpose.

  • Least likely? From exercise.

  • Of all the fascinating questions in the world, what question do you want to see answered

  • most? Let us know on Facebook or Twitter or down in the comments down below and we will

  • aim to answer those questions in a new video at the end of the month.

As you probably know by now, weve been working with Google and YouTube to answer


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B1 中級 美國腔

世界上最常見的問題。什麼是能源? (World's Most Asked Questions: What Is Energy?)

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    阿蘭 發佈於 2021 年 01 月 14 日