Where does energy come from? - George Zaidan and Charles Morton

宇宙中的所有能量是......　—George Zaidan和Charles Morton制作

翻译人员: Yixuan Liu 校对人员: Ying Minako Zhao

Energy is not easy to define.

能量不容易被定义

Things have energy,

虽然所有的物质都带有能量

but you can't hold

a bushel of energy in your hands.

但是没有人可以把

能量握在手中

You can see what it does,

你虽然能够感知能量的作用

but you can't see it directly.

但是不能直接看到它

There are different types of energy,

能量分为不同的种类

but the differences between them

各种形式的能量的不同之处

are manifested only in how they make stuff behave.

表现在它们对其它物体的影响上

We do know that the total amount

我们知道

of all the different types of energy in the universe

宇宙中的各种能量的总和

is always the same.

是守恒的

And, for chemists, two important types of energy

对于化学家们来说，有两种重要的能量

are chemical potential energy

它们分别为势能

and kinetic energy.

和动能

Potential energy is energy waiting to happen.

势能是一种等待发生的能量

Think of a stretched rubber band.

比如说一根拉长的橡皮筋

If you cut it,

如果你剪断它

all that potential energy

它所带有的势能

gets converted to kinetic energy,

便转换为动能

which is registered by you as pain.

弹到你身上让你有痛感

Like a stretched rubber band,

像拉长的橡皮筋一样

chemical bonds also store energy,

化学键也同样储存着能量

and when those bonds are broken,

当化学键断掉时

that potential energy gets converted

它所带有的势能

to other types of energy,

便转换成其它形式的能量

like heat or light,

比如热能和光能

or gets used to make different bonds.

或者是被用来形成另外的化学键

Kinetic energy is the energy of motion,

动能则是跟物体运动有关的能量

and molecules are always moving.

分子都是在不断的运动着

They're not necessarily going somewhere,

它们不一定都在移动

though they could be,

（当然这也是可能的）

but they are vibrating,

但是它们是不断的在震动

stretching,

bending,

and/or spinning.

拉伸，弯曲，或者旋转

拉伸，弯曲，或者旋转

拉伸，弯曲，或者旋转

Take methane,

例如甲烷分子

which is four hydrogens

它是由4个氢原子

attached to a central carbon,

围绕着一个碳原子

as an example.

构成的

Drawn on paper,

画在纸上

it's just a still tetrahedron.

它看起来像一个静态的四面体

But in real life, it's a jiggling mess.

但实质上，构成分子的原子是不停运动的

The kinetic energy of molecules

分子的动能

is exactly the same type of energy

跟人们在活动时

as the energy you have

所带有的能量

when you're moving around,

是同一个概念

except that you can be still

不同的是，你可以保持静止

and molecules can't.

但分子不能

If you suck the kinetic energy

如果从一组分子中

out of a group of molecules,

吸取它们的动能

they'll move less,

它们将会减少运动

but they'll never fully stop.

但不会完全停止

Now, in any group of molecules,

在任何一组分子中

some will have more kinetic energy than others.

一些分子带有的动能会比另一些多

And if we calculate

如果我们计算

the average kinetic energy of the group,

整组分子的平均动能

we'd have a number mathematically related to

我们将会得到一个与温度

temperature.

成比例的数值

So, the more kinetic energy

所以，一组分子的温度越高

a group of molecules has,

也就代表着

the higher its temperature.

它们的动能越大

And that means that on a hot day,

这意味着，天热的时候

the molecules in the air around you

在你附近空气中的分子

are spinning, stretching, bending,

会比起天冷的时候

and generally shooting around much faster

旋转，拉伸，弯曲

than on a cold day.

以及移动得更快

Now, hot and cold, by the way,

不过热和冷

are relative terms.

也是相对的概念

They're always used to compare

我们总是用其中一个

one thing to something else.

来和另一个做对比

So, on that hot summer day,

在一个炎热的夏天

the air molecules have more kinetic energy

空气中的分子比起你皮肤中的分子

than the molecules in your skin.

带有更多的动能

So, when those air molecules crash into you,

当空气中的分子撞到你时

they transfer some of their energy

它们把一部分能量

to the molecules in your skin,

传递给你皮肤中的分子

and you feel that as heat.

然后你就感到热

On a cold day,

在天冷时

the air molecules have less kinetic energy

空气中的分子比起你皮肤中的分子

than the molecules in your skin,

带有更少的动能

so when you crash into those air molecules,

当你撞到空气中的分子时

you actually transfer

你把一部分能量

some of your kinetic energy to them,

传递给它们

and you feel that as cold.

然后你便觉得冷

You can trace the path of energy around you.

你可以观察自己身边的能量转换

Try it at your next cookout.

比如下次野餐烧烤

You burn charcoal

当你烧炭时

and the release of that chemical potential energy

它们所释放出的化学势能

shows up as extreme heat and light.

表现为高温和强光

The heat then makes the molecules

这个热量会使

of your burgers, your hot dogs, or your vegetables

汉堡，热狗，蔬菜等的分子震动

vibrate until their own bonds break

直到它们的化学键断裂

and new chemical structures are formed.

然后形成新的化学结构

Too much heat and you have a charred mess;

如果过渡加热，食物会变成焦炭

just enough and you have dinner.

适度的加热，便给你带来可口的晚餐

Once in your body,

当进入你的身体后

the food molecules in your delicious,

你的可口（或烧焦了）的晚餐中的

or charred,

食物的分子

dinner get broken down,

将被拆开

and the energy released

随之释放能量

is used to either keep you alive right now

这些能量要么被用来维持你现在的身体活动

or it's stored for later in different molecules.

要么被储存在其它分子中以后使用

As night falls,

到晚上

the hot summer air cools

空气渐渐变凉

and the flow of energy into you slows.

而传递给你的能量也渐渐减少

Then, as the air reaches your skin temperature,

当空气的温度与你皮肤的温度相等时

for the briefest of moments,

在这一刹那

the flow stops.

能量的流动停止了

And then it starts up again

然后反方向的能量传递

in the opposite direction

重新开始

as energy leaves the warmer surface of your skin

能量将从相对高温的皮肤表面

to return to the universe around you,

流向你周围的宇宙

that energy, neither created nor destroyed,

能量既没有被创造，也没有被消灭

but ever shape-shifting,

只是不停地在转换形式

the chameleon phoenix of our physical world.

它称得上是物质世界的变色凤凰