What is the universe made of? - Dennis Wildfogel

宇宙由什么构成? - 丹尼斯 威尔佛格

翻译人员: Jake Hong 校对人员: Zhiting Chen

All the material objects around you

围绕在你周围的所有物质

are composed of submicroscopic units

都是由极小的单位体构成的

we call molecules.

我们叫它们分子

And molecules in turn are composed

同时分子又是由

of individual atoms.

单独的原子构成

Molecules frequently break apart

分子常常分裂

and then form new molecules.

然后构成新的分子

On the other hand,

换句话说

virtually all the atoms you come in to contact with

我们一生中接触的

through the course of your life,

所有原子

the ones in the ground beneath you,

你脚下的土地

the air you breath, the food you eat,

你所呼吸着的空气，你吃着的食物

those that make up every living thing, including you,

包括你在内，构成所有生命体的原子

have existed for billions of years

已经存在了数十亿年

and were created in places very unlike our planet.

并由与地球大为不同的空间组成

How those atoms came about is what I want to share with you.

今天我就要与你们分享这些原子是如何产生的

It all started 14 billion years ago

这些是都从140亿年前

with an event we call The Big Bang,

我们所称之为的宇宙大爆炸时开始

which resulted in a universe consisting of gas alone.

大爆炸形成了只有气体的宇宙

There were no stars and no planets.

没有任何恒星和行星

The gas was made up only of atoms

而气体只由原子组成

belonging to the simplest elements.

这些原子属于最简单的元素

It was about 75 percent hydrogen

其中大约有75%的氢气

and almost all the rest was helium.

剩下的大约24%则都是氦气

No elements like carbon, oxygen or nitrogen existed.

像碳，氧，氮等元素都是不存在的

No iron, silver or gold.

也没有铁，银或金

In some places, the density of this gas was slightly higher than in others.

在某些地方，这些气体的密度会比别的地方稍高

Due to gravity, those places attracted even more gas,

由于重力因素，密度高地方就会吸引更多的气体

which further strengthened the pull of gravity,

并且使重力增加

which then drew more gas in, and so on.

于是更多的气体被吸引，并以这种形式一直循环下去

Eventually, large dense gas balls formed,

渐渐地，形成了体积大且密度高的气体球

shrinking under their own gravity

它们依靠自身的重力

and consequently heating up on the inside.

在内部产生热量

At some point, the core of such a ball

从某种角度来看，是这种球体中心的

gets hot enough that nuclear fusion occurs.

原子核结合产生的炙热

Hydrogen atoms smash together to form helium,

氢气聚集形成氦气

accompanied by a great release of energy,

释放出巨大的能量

strong enough to counteract the shrinking force of the gravity.

足够抵消使球体缩小的重力

When the energy pushing out from the fusion reactions

从这种反应开始释放出的能量

matches the gravity pulling all the gas inwards,

与进入内部的气体重力相同的话

an equilibrium occurs.

即形成了球形体

From this a star is born.

因此一个恒星也就诞生了

Over its lifetime,

这颗恒星存在期间

the fusion reactions in the core of a massive star

从巨大的恒星中心引起的融合反应

will produce not only helium,

不仅产生了氦气

but also carbon, oxygen, nitrogen

还有碳，氧气及氮气

and all the other elements in the periodic table up to iron.

以及元素周期表中诸如铁等所有元素

But eventually, the core's fuel runs out,

但是随着中心燃料的逐渐减少

leaving it to collapse completely.

最后将消耗殆尽

That causes an unbelievably powerful explosion

那时，将引起难以置信的大爆炸

we call a supernova.

那就是我们所说的超新星

Now there are two things to note

现在我们要了解两件关于

about how supernovas create elements.

超新星如何制造的元素事

First, this explosion releases so much energy

首先，这种爆炸会释放巨大的能量

that fusion goes wild

继而形成游离的

forming elements with atoms even heavier than iron

比铁更重的元素

like silver, gold and uranium.

如银，金和铀原子等

Second, all the elements that had been accumulating

其次，聚集在恒星中心的

in the core of the star,

所有元素

like carbon, oxygen, nitrogen, iron,

如碳，氧，氮，铁

as well as all of those formed in the supernova explosion,

它们不仅是由那些超新星爆炸形成的

are ejected in to interstellar space

而且包括宇宙空间喷涌而出的

where they mix with the gas that's already there.

这些元素与已存在的气体混合

History then repeats itself.

以这种形式循环往复

Gas clouds, now containing many elements

气体云，现在除了原始的氢气和氦气以外

besides the original hydrogen and helium,

已包含着许多元素

have higher density areas

并有更高密度的空间

that attract more matter, and so on.

去吸引更多的物质

As before, new stars result.

因此，一颗新的恒星诞生了

Our sun was born this way about 5 billion years ago.

我们的太阳就是在50亿年前以这种方式诞生的

That means that the gas it arose from

可以说形成太阳的气体的状态

had itself been enriched with many elements

自宇宙形成以来

from supernova explosions since the universe began.

从超新星爆炸开始就已经形成了

So that's how the sun wound up with all the elements.

所以太阳中拥有所有的元素

It's still mostly hydrogen at 71 percent,

不过其中占最大比例的是71%的氢气

with most of the rest being helium at 27 percent.

以及27%的氦气

But bear in mind

然而要知道的是

that while the first stars were made up

即使最初的恒星

of hydrogen and helium alone,

仅由氢气和氦气构成

the remaining elements in the periodic table

元素周期表中的剩余元素

make up two percent of the sun.

还是组成了太阳的其余2%

And what about Earth?

我们的地球又如何呢？

Planets form as an incidental process to star formation

行星是依照恒星形成的过程

out of the same gas cloud as the star itself.

由同样的气体云聚合产生的

Small planets like ours don't have enough gravity

像地球这样的小行星由于重力不够

to hold on to much hydrogen or helium gas

无法留住过多的氢气和氦气

since both of those are very light.

毕竟氢气和氦气太轻了

So, even though carbon, nitrogen, oxygen and so on

因此，即使碳，氮气，氧气等

made up only two percent of the gas cloud from which Earth was formed,

只组成了形成地球的气体云的2%

these heavier elements form the bulk of our planet

但这些元素却构成了地球的地面

and everything on it.

和地上的所有东西

Think about this:

想一想

with the exception of hydrogen and some helium,

除了一些氢气和氦气

the ground you walk on,

你脚下的土地

the air you breath, you,

你呼吸的空气，以至于你本身

everything is made of atoms

全都由形成恒星内形成的

that were created inside stars.

原子所构成

When scientists first worked this out

因此当二十世纪前期

over the first half of the 20th Century,

科学家们刚得出这个结论时

the famous astronomer Harlow Shapley commented,

著名的天文学哈洛沙普利说：

"We are brothers of the boulders, cousins of the clouds."

“我们都是岩石的兄弟，云朵的表亲。”