了解宇宙是如何运行的（2010）

How the Universe Works S01E04

Part 2 April 18, 2021, 7:56 p.m.

恒星形成的过程就是这么狂暴
That really shows you how violent
a process star formation is.
这些喷射流的直径达许多光年
These jets are many light years across.
有东西令物质迅速加速
Something is literally
accelerating material very fast
飞越想象不到的距离
across unimaginable distances.
重力令压力持续
Gravity keeps the pressure on,
吸入气体和尘粒, 使它们相撞
sucking in gas and dust particles
that smash into each other,
产生更多热力
generating more and more heat
其后50万年
Over the next half a million years,
年轻恒星变得更小、更明亮及更热
the young star gets
smaller, brighter and hotter.
它的核心温度高达1500万度
tempreture at its core,
reach 50 million degrees.
就只有在如此高温
Only at that mind-boggling temperature
气体原子才能开始熔合
can atoms of gas begin to fuse together,
释放大量能量
releasing massive amounts of energy.
就是这样, 一颗恒星诞生了
And just like that, a star is born.
它会发亮几百万、几十亿…
It will shine for
millions, even billions,
以至几万亿年
or perhaps even trillions of years.
恒星产生大量热和光, 达数十亿年
Stars produce massive amounts of
heat and light over billions of years.
但那需要极大量燃料
But that takes fuel, and lots of it
20世纪初以前, 没人知道燃料是啥
Until the early 20th century, no
one had any idea what this fuel was.
上世纪初, 物理学面对最大的问题
The greatest problem facing physics
at the turn of the last century
是: 恒星的能量源自甚么?
was what drives the energy of stars.
其实你只需要往外面看看
All you had to do was look outside
就会明白人类的知识存在一个漏洞
and realise there was a huge
gaping hole in our understanding.
为解开恒星的秘密
To solve the secret of the stars,
我们需要一个新引掣
we needed a new engine,
需要极厉害的能量来源
we needed a fabulous source of energy
足以驱动恒星几十亿年
that could drive a star for
billions of years at a time.
结果由一位天才发现了: 爱因斯坦
And it took a genius to
discover it, Albert Einstein.
其理论证实恒星能开♥发♥原子里能量
His theories proved that stars could
tap into the energy inside atoms.
恒星的秘密就是爱因斯坦的方程式
The secret of the stars
is Einstein's equation:
E=mc2
E=mc2
从某层面看, 组成人体的物质
In some sense, matter,
which makes up our body.
是聚能
is concentrated energy,
condensed energy,
聚能凝聚为组成我们宇宙的原子
energy that has condensed into the
atoms that make up our universe.
爱因斯坦显示令原子相撞
Einstein showed that it's
possible to release this energy
就有可能释放这股能量
by smashing atoms together.
它称为核聚变
It's called fusion,
也就是驱动恒星的力量
the same force that powers stars.
极细小亚原子粒子的物理特性
It's astonishing to realise that the physics
of the very small subatomic particle physics
决定恒星的结构和性质
determines the structure
and nature of stars.
从爱因斯坦的理论
From Einstein's theories,
我们学会怎样释放原子内的能量
we learned how to release
the energy inside an atom.
科学界正设法模拟恒星的能量来源
Now science is trying to
simulate a star's energy source
以便在实验室控制核聚变的强度
to control the power of fusion in a lab.
在英国, 牛津附近的这个实验室
Inside this laboratory
near Oxford, England,
有一部8万磅重的机器
there's an 80,000-pound machine.
每天, 安迪寇克和组员
Every day, Andy Kirk and his team
都在地球上把它变成一颗恒星
transform it into a star, on Earth.
这部机器叫托卡马克装置
This machine is called a tokamak.
其实就是一个巨型磁瓶
It's effectively a
large magnetic bottle,
一个盛载极热等离子体的笼
a cage to hold a very hot plasma.
我们能重塑恒星内的情况
We're able to recreate the
conditions within a star.
在托卡马克装置内
Inside the tokamak,
氢原子很自然地互相排斥
hydrogen atoms naturally
repel each other.
为令氢原子相撞
To smash hydrogen atoms together,
托卡马克装置把氢原子
the tokamak heats them
加热至逾3亿度
to more than 300 million degrees.
在极高温下
At these temperatures,
充满能量的氢原子以极速移♥动♥
the energised hydrogen
atoms are moving so fast
无可避免地互相碰撞
they can't avoid
smashing into each other.
加热原子, 热力就是动力
If you heat it up, heat is motion,
热粒子的动力足以压过排斥力
and the motion of hot particles will be
enough to overcome the repulsive force.
所有人员请准备离开托卡马克装置
All personnel should prepare to
leave the tokamak machine area.
当一切无误
When everything goes right,
就能得到宇宙间最棒的发电厂
the result is the single best
power plant in the universe:
核聚变
nuclear fusion.
以每秒1000英里的高速移♥动♥
Travelling at a thousand miles a second,
氢原子互相碰撞并熔合
the hydrogen atoms smash
into each other and fuse
形成一种新元素: 氦
creating a new element: helium,
和小量纯能量
and a small amount of pure energy.
氢较氦稍重
The hydrogen gas weighs
slightly more than the helium.
燃烧过程导致失去质量
You lost mass in the process of burning.
失去的质量变成能量
That mass that you lost, the
missing mass, turns into energy.
托卡马克装置只能维持核聚…
The tokamak can only maintain fusion
极短时间
for a fraction of a second.
但真正恒星的核聚变持续几十亿年
But inside a real star, fusion
continues for billions of years.
原因极简单: 大小
The reason is simple: size.
驱动恒星的引掣是重力
The engine which drives
a star is gravity.
因此恒星很巨大, 是庞然巨物
That's why stars are
big. Stars are huge.
需要极大重力才能压缩恒星
You need that amount of gravity
in order to compress the star
以制♥造♥足以引发核聚变的热力
to create fantastic amounts of heat,
sufficient to ignite nuclear fusion.
那就是恒星的秘密, 恒星发亮之因
That is the secret of the
stars, that's why stars shine.
恒星核心的核聚变
Fusion at the core of a star
每秒产生10亿个核弹的爆♥炸♥力
generates the explosive force of a
billion nuclear bombs every second.
恒星是巨型氢气弹
A star is a gigantic hydrogen bomb,
那为甚么它不会炸成碎片?
so why doesn't it simply blow apart?
因为重力挤压着恒星的外层
It's because gravity is compressing
the outer layers of the star.
重力和核聚变在这场激战中角力
Gravity and fusion lock
horns in an epic battle.
这种紧绷状态持续
We have this constant
tension between gravity,
重力想把恒星压碎成为碎片
which wants to crush
a star to smithereens,
而核聚变释放的能量
and also the energy released
by the fusion process,
却想炸散恒星
which wants to blow the star apart.
那股张力互相抗衡, 制♥造♥出恒星
And that tension, that
balancing act, creates a star.
恒星一生都面对这种力量斗争
This power struggle plays out
over the entire life of a star,
两股庞大的自然力量处于僵持局面
two awesome forces of nature
in a dynamic stand'--off.
激战期间, 恒星爆发光和热
As that battle rages, the
star blasts out light and heat,
但还有更具破坏力的东西
but also something far more destructive.
每束星光都踏上史诗式的旅程
Each beam of starlight
makes an epic journey.
光以时速6亿7千万英里速度飞驰
Light travels at 670
million miles an hour.
光束能在1秒间环绕地球7次
A beam of light could travel around
the Earth seven times in one second.
宇宙间没其它东西移♥动♥得更快
Nothing in the universe moves faster.
但大部分恒星都距离甚远
Yet most stars are so far away,
它们的光要几百、几千、几百万…
their light takes hundreds,
thousands, millions,