What happened to antimatter? - Rolf Landua

反物質到哪裡去了？ - 羅爾夫藍卓 (Rolf Landua)

Translator: Andrea McDonough Reviewer: Jessica Ruby

譯者: Jephian Lin 審譯者: Allen Li

Is it possible to create something out of nothing?

有可能無中生有嗎？

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

或更精確的說 能量可以轉換成物質嗎？

Yes, but only when it comes together

可以，但只會和雙胞胎兄弟—

with its twin, antimatter.

反物質，一起出現

And there's something pretty mysterious about antimatter:

關於反物質，有件很神秘的事：

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

它存在的量，遠比它應有的量少

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

讓我們從最有名的物理公式說起：

E equals m c squared.

能量 = 質量 x 光速的平方

It basically says that mass is concentrated energy,

基本上是說，質量是濃縮的能量

and mass and energy are exchangeable,

而質量和能量是可以互換的

like two currencies with a huge exchange rate.

就像是匯率極高的兩種貨幣

90 trillion Joules of energy

90 兆焦耳的能量

are equivalent to 1 gram of mass.

等於 1 公克的質量

But how do I actually transform energy into matter?

要怎樣才能把能量轉換成物質呢？

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

關鍵是「能量密度」

If you concentrate a huge amount

如果你把巨大的能量

of energy in a tiny space,

集中到很小的空間

new particles will come into existence.

新的粒子就會出現

If we look closer,

如果我們更仔細看

we see that these particles always come in pairs,

我們會看到 這些粒子總是成對出現

like twins.

就像是雙胞胎

That's because particles always have a counterpart,

因為每個粒子都有對應的夥伴

an antiparticle,

叫做反粒子

and these are always produced

它們總是依照

in exactly equal amounts: 50/50.

50 比 50 等量出現

This might sound like science fiction,

這聽起來像是科幻小說

but it's the daily life of particle accelerators.

但對粒子加速器來說，卻稀鬆平常

In the collisions between two protons

當兩個質子

at CERN's Large Hadron Collider,

在歐洲核子研究中心的 大型強子對撞機中相撞

billions of particles and antiparticles

每秒會產生數十億個

are produced every second.

粒子與反粒子

Consider, for example, the electron.

比如說，像是電子

It has a very small mass and negative electric charge.

質量很小，而且帶負電

It's antiparticle, the positron,

它的反粒子，也就是正電子

has exactly the same mass,

質量完全相同

but a positive electric charge.

但是帶正電

But, apart from the opposite charges,

除了電荷相反以外

both particles are identical and perfectly stable.

兩種粒子一模一樣，而且完全穩定

And the same is true for their heavy cousins,

這對於它較重的表兄弟也成立

the proton and the antiproton.

也就是質子與反質子

Therefore, scientists are convinced

因此，科學家相信

that a world made of antimatter

反物質組成的世界

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

看起來、摸起來、聞起來 都像我們的世界

In this antiworld,

在反世界中

we may find antiwater,

我們可以找到反水、

antigold,

反金、

and, for example,

或是，比如說

an antimarble.

反彈珠

Now imagine that a marble and an antimarble

現在想像一下，彈珠和反彈珠

are brought together.

放在一起

These two apparently solid objects

這兩個看似堅固的物體

would completely disappear

會完全消失

into a big flash of energy,

變成巨大的能量閃光

equivalent to an atomic bomb.

相當於一顆原子彈

Because combining matter and antimatter

因為將物質與反物質結合

would create so much energy,

會產生極大的能量

science fiction is full of ideas

科幻小說裡面有許多

about harnessing the energy stored in antimatter,

用反物質儲存能量的想法

for example, to fuel spaceships like Star Trek.

例如《星際爭霸戰》裡 太空船的燃料

After all, the energy content of antimatter

畢竟，反物質所含的能量

is a billion times higher than conventional fuel.

是傳統燃料的十億倍

The energy of one gram of antimatter would be enough

一公克反物質的能量

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

足夠開車繞地球一千圈

or to bring the space shuttle into orbit.

或讓太空梭進入軌道

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

為什麼我們不用反物質產生能量呢？

Well, antimatter isn't just sitting around,

這個嘛，反物質並不會坐著

ready for us to harvest.

等我們開採

We have to make antimatter

我們必須先製造反物質

before we can combust antimatter,

才能燃燒反物質

and it takes a billion times more energy

而要製造反物質

to make antimatter

得先花十億倍

than you get back.

未來可回收的能量

But, what if there was some antimatter in outer space

但若外太空裡有些反物質

and we could dig it out one day

有一天我們可從某處的

from an antiplanet somewhere.

反行星上開採呢？

A few decades ago, many scientists believed

幾十年前，許多科學家相信

that this could actually be possible.

這是有可能的

Today, observations have shown

現今，觀測結果顯示

that there is no significant amount of antimatter

在已觀察到宇宙的任何地方

anywhere in the visible universe,

都找不到大量的反物質

which is weird because, like we said before,

這是很詭異的，如我們先前所說

there should be just as much antimatter

反物質的數量應該要

as there is matter in the universe.

和宇宙中物質的數量相等

Since antiparticles and particles

因為反粒子和粒子

should exist in equal numbers,

存在數目應該相等

this missing antimatter?

反物質到哪裡去了？

Now that is a real mystery.

這真是一個謎

To understand what might be happening,

要了解可能發生了什麼事

we must go back to the Big Bang.

我們必須回到大霹靂

In the instant the universe was created,

在宇宙誕生的瞬間

a huge amount of energy was transformed into mass,

大量的能量被轉換成質量

and our initial universe contained

最初的宇宙包含了

equal amounts of matter and antimatter.

等量的物質與反物質

But just a second later,

但僅僅一秒之後

most matter and all of the antimatter

大部份的物質，及所有的反物質

had destroyed one another,

就互相破壞消失了

producing an enormous amount of radiation

產生大量的輻射

that can still be observed today.

我們至今仍觀測得到

Just about 100 millionths

只有約一億分之一的

of the original amount of matter stuck around

原始物質留了下來

and no antimatter whatsoever.

沒有任何反物質倖存

"Now, wait!" you might say,

「等等！」你可能會這麼說：

"Why did all the antimatter disappear

「為什麼所有的反物質都不見了，

and only matter was left?"

而只有物質留下來？」

It seems that we were somehow lucky

我們好像還蠻幸運的

that a tiny asymmetry exists

有一點點的不對稱

between matter and antimatter.

存在於物質和反物質之間

Otherwise, there would be no particles at all

否則，這宇宙中

anywhere in the universe

將會沒有任何粒子

and also no human beings.

也不會有人類

But what causes this asymmetry?

是什麼造成這樣的不對稱呢？

Experiments at CERN are trying to find out the reason

歐洲核子研究中心的實驗 正試著找出答案

why something exists

為什麼有些東西留下來了？

and why we don't live in a universe

為什麼我們的宇宙

filled with radiation only?

不是只充斥著輻射？

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

至今，我們還是不知道答案