What happened to antimatter? - Rolf Landua

Translator: Andrea McDonough Reviewer: Jessica Ruby

翻译人员: Tianshu Wang 校对人员: Mingyu Cui

Is it possible to create something out of nothing?

凭空造物可能吗？

Or, more precisely, can energy be made into matter?

更确切地说，能量能转化成物质吗？

Yes, but only when it comes together

可以，但它需要和它的兄弟——

with its twin, antimatter.

反物质相遇。

And there's something pretty mysterious about antimatter:

关于反物质，有件很神秘的事：

there's way less of it out there than there should be.

它的实际存在量比理论上要少得多。

Let's start with the most famous physics formula ever:

让我们先看一个 迄今最著名的物理学方程：

E equals m c squared.

E=mc^2

It basically says that mass is concentrated energy,

它主要是说，质量是浓缩的能量，

and mass and energy are exchangeable,

质量和能量可以互相转化，

like two currencies with a huge exchange rate.

就像两种汇率差距巨大的货币。

90 trillion Joules of energy

1克质量

are equivalent to 1 gram of mass.

相当于90万亿焦耳的能量。

But how do I actually transform energy into matter?

但我具体该如何 将能量转化为质量？

The magic word is <i>energy density</i>.

关键是：能量密度。

If you concentrate a huge amount

如果你在一个狭小的空间中

of energy in a tiny space,

浓缩一大股能量，

new particles will come into existence.

新的粒子就会产生。

If we look closer,

如果研究地更仔细些，

we see that these particles always come in pairs,

我们就会发现，这些粒子总是成对出现，

like twins.

就像双胞胎。

That's because particles always have a counterpart,

这是因为，粒子都有个副本，

an antiparticle,

也就是反粒子，

and these are always produced

正反粒子的产生

in exactly equal amounts: 50/50.

总是精确的1比1。

This might sound like science fiction,

这听起来很科幻，

but it's the daily life of particle accelerators.

但却是粒子加速器中的日常。

In the collisions between two protons

欧洲核子研究中心CERN的 大型强子对撞机中，

at CERN's Large Hadron Collider,

两个质子相撞，

billions of particles and antiparticles

每秒能产生

are produced every second.

数十亿粒子和反粒子。

Consider, for example, the electron.

拿电子举个例子：

It has a very small mass and negative electric charge.

电子的质量很小，带负电荷。

It's antiparticle, the positron,

它的反粒子，正电子，

has exactly the same mass,

与它质量完全相等，

but a positive electric charge.

但是带正电荷。

But, apart from the opposite charges,

不过除了电荷相反，

both particles are identical and perfectly stable.

两种粒子完全相同，也都非常稳定。

And the same is true for their heavy cousins,

比它们更重的粒子， 质子和反质子，

the proton and the antiproton.

也是如此。

Therefore, scientists are convinced

科学家因此相信，

that a world made of antimatter

反物质的世界

would look, feel, and smell just like our world.

看起来、摸起来、闻起来 都和我们的世界一样。

In this antiworld,

在反世界中，

we may find antiwater,

也许有反水、

antigold,

反金，

and, for example,

还有，比如

an antimarble.

反大理石。

Now imagine that a marble and an antimarble

想象一下，大理石和反大理石

are brought together.

被放在一起。

These two apparently solid objects

这两块看起来很稳定的东西

would completely disappear

将会完全消失，

into a big flash of energy,

变成一大波能量。

equivalent to an atomic bomb.

和原子弹爆炸相似。

Because combining matter and antimatter

由于物质和反物质相遇

would create so much energy,

能释放这么多能量，

science fiction is full of ideas

科幻小说中常常出现

about harnessing the energy stored in antimatter,

控制反物质中的能量，

for example, to fuel spaceships like Star Trek.

比如，用来驱动 《星际迷航》中的飞船。

After all, the energy content of antimatter

毕竟，反物质中的能量

is a billion times higher than conventional fuel.

比常规燃料高了十亿倍。

The energy of one gram of antimatter would be enough

1克反物质的能量

for driving a car 1,000 times around the Earth,

就足以让一辆车 绕地球1000圈，

or to bring the space shuttle into orbit.

或者把航天飞机送入轨道。

So why don't we use antimatter for energy production?

那我们怎么还不 用反物质来制造能量？

Well, antimatter isn't just sitting around,

因为反物质并不是随处可见，

ready for us to harvest.

任由我们丰收。

We have to make antimatter

烧反物质前，

before we can combust antimatter,

我们必须先制造它们，

and it takes a billion times more energy

而目前制造反物质消耗的能量

to make antimatter

比烧它们能得到的，

than you get back.

多十亿倍。

But, what if there was some antimatter in outer space

但如果宇宙中就有反物质，

and we could dig it out one day

而且有一天

from an antiplanet somewhere.

能被我们从某处的反行星上开采出来。

A few decades ago, many scientists believed

几十年前，很多科学家相信，

that this could actually be possible.

这的确是可能的。

Today, observations have shown

如今，观察发现，

that there is no significant amount of antimatter

可见宇宙中，

anywhere in the visible universe,

哪里都没有可观的反物质储备。

which is weird because, like we said before,

听起来很古怪，因为如之前所言，

there should be just as much antimatter

宇宙中，反物质

as there is matter in the universe.

应该和物质一样多。

Since antiparticles and particles

而反粒子和粒子

should exist in equal numbers,

应该以同等数量存在，

this missing antimatter?

那反物质去哪了呢？

Now that is a real mystery.

现在这真的是个迷。

To understand what might be happening,

为了明白可能发生了什么，

we must go back to the Big Bang.

我们必须回头看看大爆炸。

In the instant the universe was created,

在宇宙产生的那一刻，

a huge amount of energy was transformed into mass,

巨大的能量被转化成了物质，

and our initial universe contained

而初始宇宙

equal amounts of matter and antimatter.

包含了等量的物质和反物质。

But just a second later,

但一秒钟后，

most matter and all of the antimatter

大部分物质和所有反物质

had destroyed one another,

同归于尽了，

producing an enormous amount of radiation

这带来了大量辐射，

that can still be observed today.

至今仍可观测到。

Just about 100 millionths

初始物质中，

of the original amount of matter stuck around

只有十亿分之一留了下来，

and no antimatter whatsoever.

反物质则消失殆尽。

"Now, wait!" you might say,

你也许会说：“不对，等一下！

"Why did all the antimatter disappear

为什么所有反物质都消失了，

and only matter was left?"

却有物质留下？“

It seems that we were somehow lucky

我们似乎很幸运，

that a tiny asymmetry exists

因为物质和反物质中，

between matter and antimatter.

有一点点不对称。

Otherwise, there would be no particles at all

否则，宇宙中，

anywhere in the universe

就完全不会有任何粒子了，

and also no human beings.

人类也就不会出现。

But what causes this asymmetry?

那这不对称又是怎么产生的？

Experiments at CERN are trying to find out the reason

CERN的实验试图找出原因：

why something exists

为什么有物质留了下来，

and why we don't live in a universe

所以我们的宇宙

filled with radiation only?

不是只有辐射？

But, so far, we just don't know the answer.

但到目前为止，我们还不知道答案。