宇宙时空之旅（2014）

Cosmos: A SpaceTime Odyssey S01E04

Part 4 April 25, 2021, 12:39 p.m.

却不能超过光速
any more a barrier than the speed of sound?
这不仅是因为光的传播速度
The answer is not just that light travels
比音速快将近一百万倍
about a million times faster than sound.
这也不像建造第一台超音速飞机一样
And it's not merely an engineering problem,
是一个简单的工程问题
like building the first supersonic jet.
反之光的速度上限
Instead, the light barrier
是最基本的自然定律
is a fundamental law of nature,
和重力一样基础
as basic as gravity.
爱因斯坦找到了他所认为的世界的绝对框架
Einstein found his absolute framework for the world,
在所有物质都在相对运动的宇宙中
this sturdy pillar among all the relative motions
不变的基石
within the motions of the cosmos.
所有光以同样速度传播
Light travels just as fast,
不管它的光源运行速度是多少
no matter how fast or slow its source is moving.
光速是恒定不变的相对一切事物都是如此
Speed of light is constant, relative to everything else.
没有东西可以追上光
Nothing can ever catch up with light.
自然规律最重要的一点
The thing about the laws of nature
就是它是不可违背的
is that they're unbreakable.
物理学家的工作就是去找到这些规律
The job of physicists is to discover these commandments,
那些不为文化差异和时过境迁所动
the ones that do not vary from culture to culture
永恒的定律
or time to time
在浩瀚宇宙里掌握真理
and hold true throughout the cosmos.
爱因斯坦认为这也是为什么
That's why, as Einstein showed,
在接近光速时会发生奇妙的现象
funny things happen close to the speed of light.
以接近光速运行
Traveling close to the speed of light
可以让生命永恒
is kind of an elixir of life
因为你的生物钟和相对于你甩下的一切
because your biological clock slows down
变得慢下来
relative to those you leave behind.
这个现象可能能为我们这些
This phenomenon may provide us humans,
只能活一个世纪的人类
who only live for a century or so,
一个去到其他恒星的可行方法
a practical means to travel to the stars,
去另一个由第四维度时空带来的
where the magic show of spacetime
奇妙世界
really gets crazy.
十九世纪的天文学家威廉·赫歇尔
The 19th-century astronomer William Herschel
喜欢和他的儿子约翰
loved to share the wonders of the universe
分享宇宙的神秘
with his son John.
我曾经有个朋友一个很聪明的人
I once had a friend, very clever fellow,
来自利兹[英国城市]的天文学家和牧师
an astronomer and a parson at Leeds,
名字叫作约翰·米歇尔
by the name of John Michell.
他在你还是个婴儿时就凄惨死去
Poor man died when you were a babe,
愿上帝让他安息
God rest his soul.
他认为有些恒星是隐形的
He held that some stars are invisible.
它们是存在的但是我们看不到它们
They really exist, but we shall never see them.
米歇尔叫它们暗星
"Dark Stars," Michell called them.
爸爸恕我直言
With all due respect, father,
你的朋友肯定是错了
surely your friend was mistaken.
如果没有人能看到它们
If no one can see them,
那人们怎么可能知道它们存在呢
then how can we possibly know they exist?
你看到了留下这些脚印的人吗约翰
Did you see the man who left those footprints, John?
没有怎么了爸爸
Why, no, father.
我没看到
I did not.
但你知道他们一定来过这里对吗
But do you know that he exists?
约翰·米歇尔可能是你没听说过的
John Michell is one of the greatest scientists
最伟大的科学家之一
you've probably never heard of.
他十八世纪时在英国工作
He lived and worked in England in the 18th century.
就算他曾经有过画像那也不可能还在了
If he ever sat for a portrait, it no longer exists.
一个相识的人曾这样形容他
He was once described by an acquaintance
一个小矮子
as "a short little man,
肤色黝黑大腹便便
of black complexion, and fat."
米歇尔设想过有一颗巨大的恒星
Michell imagined a star so big,
巨大到没有物体甚至光
so massive, that nothing, not even light,
可以逃脱它的重力场
could escape its gravitational grip.
你能找到那颗暗星吗
Can you find the dark star?
你不能直接通过肉眼看到它
You can't see it with your eyes, not directly,
但是它也会在宇宙里留下它的足迹
but it may leave a kind of footprint on the cosmic shore.
米歇尔意识到我们也许可以
Michell realized that we might be able to detect
借助暗星巨大的重力探测到它们
some of these dark stars because of their extreme gravity.
如果它恰好靠近
If one happened to be near
一颗更小更明亮的伴星
a smaller, luminous companion star,
那这颗恒星可能会看似被巨大引力束缚
that star would appear to travel in a tight orbit
绕着虚空运行
around nothing.
即使我们看不到
Even though we can't see it,
我们也会知道有一个大质量天体
we know something with a lot of mass
存在于这里
has to be right there.
那就是暗星
A dark star,
或者在今天我们称之为黑洞
or what today we call a black hole.
黑洞到底长什么样子
What does a black hole look like
它的内部又会是如何
and what would it be like inside?
我们会提到的但是首先
We'll get there, but first,
我们先在我的故乡稍作停留
let's make a pit stop in my hometown,
纽约
New York City,
这里在我的眼里
where it's always seemed to me
一切事物总是永不停歇
that everything is in constant motion.
我大部分时间都生活在这里
I've lived here most of my life.
总有新鲜的事物出现
There's always something new to see.
但是有一个事永远不变重力
But one thing never changes-- gravity.
地球上的重力在过去的
Gravity on Earth has been the same
四十五亿年里都不曾改变
for the past four and a half billion years.
那么万一如今我们可以改变它呢
But what if, today, we could alter it?
根据爱因斯坦所说重力源自于
Gravity is a distortion in the shape of spacetime
四维时空的扭曲
as Einstein showed.
空间可以无限地膨胀收缩和扭曲
Space can expand and contract and warp without limit.
如果地球的大小和密度改变了哪怕一点点
If the Earth's size or density were even a little different,
它的重力场也会随之改变
its gravity would be, too.
可能性是无穷无尽的
There's an infinite range of possibilities.
纽约客们在家里
New Yorkers feel right at home
受到地球的重力吸引
in the gravitational pull of the Earth,
称之为一个G
called "one g."
假设我们关闭一条街的重力
Suppose we turn off the gravity on one of its streets.
所有在运动的人和物体
People and objects that were already in motion
都会离开地面开始飞行
are launched into flight.
或者我把重力提高到
Now what if I turn the gravity up
比如说八或九个G
to, say, eight or nine g's?
出于人道主义
Out of compassion,
我们疏散一下现场
let's evacuate the area.
这大概是一个战斗飞行员
This is about the same g-force
在高速转弯时感到的重力值
that a fighter pilot in a high-speed turn would feel.
只经历几分钟不会对你造成伤害
A few minutes of this wouldn't hurt you,
但是绝对不好受
but it wouldn't be comfortable.
在十万个G时
At 100,000 g's,
即使是消防栓
even fire hydrants become crushed
也会被自身重量所压碎
by their own enormous weight.
但是当一百万个G时
But at millions of g's,
甚至连光也会向重力屈服
even light bows to gravity.
光还是按照它的既定速度传播
The light still moves at its constant speed,
但是它无法逃脱
but it cannot escape
米歇尔所说的暗星
Michell's dark star...
我们所说的黑洞
Our black hole.
最近的黑洞可能比你想的近许多
And the nearest one may be closer than you think.
不是所有恒星都会变成黑洞
Not every star can become a black hole.
一千颗中只有一颗能有足够的质量
Only about one in a thousand is massive enough.
最近的一处离地球可能不超过一百光年
The nearest one could be within 100 light years of Earth.
黑洞不像科幻小说所说
Black holes aren't the mythic cosmic
是神秘宇宙中的吸尘器
vacuum cleaners of science fiction
它们不会到处蚕食没有防备的世界
they don't go around gobbling up unsuspecting worlds.
只能是你靠近它
You've got to come to them.
但如果你这么做了
But if you do,
它可能会成为你最后见到的东西
it might be the last thing you ever see.
那就是我们和几百万G的重力做抵抗
That was us resisting a few million g's of gravity.
不要忘记它甚至会吞噬光
Don't forget, that thing swallows light.
我们要和它保持距离
We'll keep our distance.