宇宙（2021）

喷气机如此强大，以至于它们剥离了大气
Jets so powerful they stripped the atmospheres
来自他们路径上的任何行星。
from any planets in their path.
辐射使每一个类似地球的世界
And radiation rendered every Earth-like world
一千光年之内无法居住。
within a thousand light years uninhabitable.
但这就是射手座 A* 爆发的规模
But such was the scale of Sagittarius A*'s outbursts
银河系那么远，那么远……
that far, far out in the galaxy...
……毁灭……
..destruction...
..转向创作。
..turned to creation.
如果您正在寻找生命不仅仅起源于地球的原因
If you're looking for reasons why life not only began here on Earth
但能够在近 40 亿年的时间里繁荣昌盛
but was able to prosper for the almost four billion years it took
让它演变成我们今天看到的复杂的生活世界，
for it to evolve into the complex living world that we see today,
那么它可能看起来有点牵强
then it might seem a bit of a stretch
指向我们银河系中心的一个超大质量黑洞
to point to a supermassive black hole at the centre of our galaxy
并说这是原因之一。
and say that's one of the reasons why.
但我们现在开始怀疑那些大倾盆
But we're now beginning to suspect that those great outpourings
来自射手座 A* 的能量发挥了关键作用
of energy from Sagittarius A* played a crucial role
使银河系的这个区域成为生命可以繁衍的地方……
in making this region of the galaxy one in which life can flourish...
..因为人马座A*喷出的热气
..because the hot gas ejected by Sagittarius A*
对银河系有镇静作用。
had a calming effect on the galaxy.
现在，你可能认为热气云会产生更多的恒星，
Now, you might think that a hot gas cloud would produce more stars,
但事实上，事实恰恰相反，
but, in fact, the opposite is true,
因为热意味着一切都在快速移♥动♥
because hot means that everything is moving around very fast
这使得重力更难以抓住一切
and that makes it more difficult for gravity to grab hold of everything
并将其折叠以形成恒星。
and collapse it to form stars.
所以人马座A*减少了星星的数量
So Sagittarius A* reduced the number of stars
在银河系的这个区域形成的。
that formed in this region of the galaxy.
这是一件好事。
And that's a good thing.
想象一下，如果有一些巨星在附近形成
Imagine if there was some giant star that had formed close by
在超新星爆♥炸♥中爆♥炸♥。
the exploded in a supernova explosion.
如果你是变形虫那可不是什么好事
That would not be a good thing if you're an amoeba
有一天你会设计成爱因斯坦。
and you have designs one day on evolving into Einstein.
因此，人马座 A* 转向了一个潜在的暴♥力♥区域
So, Sagittarius A* turned what is potentially a violent region
我们的银河系变成一个和平的银河系。
of our galaxy into a peaceful one.
人马座A*排出的暖气
The warm gases pushed out by Sagittarius A*
减缓恒星形成的速度。
slowed the rate of star formation.
并且，在一个安静的区域围绕一颗黄色的小星星
And, around one small yellow star in a quiet region
在银河系外旋臂不合时宜的一端……
at the unfashionable end of the outer spiral arms of the galaxy...
..四十亿年的稳定
..four billion years of stability
使一切变得不同。
made all the difference.
现在，当然，有很多事情是必要的
Now, of course, there are many things that are necessary
使生命存在于行星上。
for life to exist on a planet.
名单之多令人难以想象，但我认为它很有趣
The list is unimaginably vast, but I think it is interesting
在那个清单上有这个奇怪的物体，
that on that list there is the presence of this strange object,
一个黑洞，人马座A*，
a black hole, Sagittarius A*,
数万光年之外。
tens of thousands of light years away.
我们银河系的中心。
The centre of our galaxy.
清除了大部分气体、尘埃和恒星
Having cleared out much of the gas, dust and stars
曾经躺在附近...
that once lay close by...
..没有什么可以享用的了。
..there was little left to feast on.
我们的黑洞沉默了。
Our black hole fell silent.
费米发现的巨大气泡
The enormous bubbles spotted by Fermi...
..辉煌过去的回声。
..echoes of a glorious past.
今天，射手座A*是一个沉睡的巨人……
Today, Sagittarius A* is a sleeping giant...
……一只沉思的野兽……
..a brooding beast...
..慢炖。
..operating on a slow simmer.
射手座A*从暴♥力♥驱逐舰的旅程
Sagittarius A*'s journey from violent destroyer
银河系的雕塑家，我们今天看到的沉睡的巨人
to sculptor of the galaxy to the sleeping giant that we see today
在过去的 20 年里通过观察数据拼凑起来
has been pieced together over the last 20 years by observational data
来自钱德拉和费米等望远镜。
from telescopes such as Chandra and Fermi.
但确实有很大的不同
But there's a very big difference indeed
在了解黑洞如何与其环境相互作用之间，
between knowing how a black hole interacts with its environment,
它是如何塑造一个星系的，
how it sculpts a galaxy,
以及它在深层次上的实际情况。
and what it actually is at a deep level.
里面到底是什么样子的？
What is it really like inside?
斯蒂芬霍金：黑洞挑战最基本的原理
STEPHEN HAWKING: Black holes challenge the most basic principle
关于宇宙的可预测性
about the predictability of the universe
以及历史的确定性。
and the certainty of history.
什么都不能从黑洞里出来，
Nothing can get out of a black hole,
或者是这样认为的。
or so it was thought.
正是通过展望未来，我们才开始探索
It's by looking into the future that we're beginning to explore
黑洞的深奥之谜。
the deep mystery of black holes.
数十颗恒星围绕人马座 A* 运行。
Dozens of stars orbit around Sagittarius A*.
有些距离事件视界只有几十亿英里。
Some passing just a few billion miles from the event horizon.
银河尺度上头发的宽度。
A hair's breadth on galactic scales.
这些飞越可能会产生致命的后果。
These flybys could have fatal consequences.
其中一些恒星可能在轨道上有行星。
Some of these stars will likely have planets in orbit.
可能离野兽太近的行星。
Planets that may stray too close to the beast.
飞蛾扑火。
A moth to a flame.
从它的母星被拉向深渊。
Pulled from its parent star towards the abyss.
如果这颗行星在它向内的旅程中幸存下来......
If the planet survives its journey inwards...
..我们可以站在它的表面
..and we could stand on its surface
并眺望远方的宇宙……
and look out into the universe beyond...
..我们会看到空间和时间变得越来越扭曲。
..we would see space and time becoming increasingly distorted.
但最终，潮汐引力变得太强了。
But eventually, tidal gravitational forces become too strong.
无情地，奇点在等待。
Inexorably, the singularity awaits.
时间的尽头，
The end of time,
所有路径终止的地方。
where all paths terminate.
数万亿年来，人马座A*周围的所有恒星
Over trillions of years, all the stars around Sagittarius A*
会逐渐消退和死亡。
will gradually fade and die.
在越来越多的外星世界，黎明不会到来。
On more and more alien worlds, the dawn will fail to come.
但我们的超大怪物会继续存在，
But our supermassive monster will go on,
它的秘密被密封在里面。
its secrets sealed away inside.
看似永远。
Seemingly forever.
我们预测有一天黑洞将成为唯一的存在
We predict that one day black holes will be all that remains
在宇宙中。 最后的黑暗时代。
in the universe. The final Dark Age.
鸟爪
BIRD CAWS
如果没有任何东西可以从黑洞中逃脱，如果人马座 A*
If nothing can ever escape from black holes, if Sagittarius A*
真的是永恒的牢狱，那么这就是结局
really is an eternal prison, then this is the end
宇宙的故事。
of the story of the universe.
黑暗中散落着时空的空洞。
Darkness littered with holes in space time.
但我们不认为这是故事的结局。
But we don't think this is the end of the story.
我们现在相信，即使是黑洞也会死亡。
We now believe that even black holes die.
他们的死是由看似
And their deaths come at the hands of what might seem
大约五年前发现的一个无关紧要的细节。
an inconsequential detail discovered almost five decades ago.
1975 年，斯蒂芬霍金发表了一篇引人注目的论文
In 1975, Stephen Hawking published a remarkable paper
他在其中表明黑洞并不完全是黑色的。
in which he showed that black holes are not completely black.
它们发出微弱的光芒。 他们有温度。
They glow faintly. They have a temperature.
这是他关于黑洞温度的美丽方程式。
And here's his beautiful equation for the temperature of a black hole.
你可以看到有一些很深的事情正在发生
And you can see that there's something deep going on
因为这里面包含了所有的物理知识。 有了这件事，
because this has got all the physics in it. With this thing here,
h-bar，这是普朗克常数，与量子力学有关，
h-bar, it's Planck's constant and that's to do with quantum mechanics,
亚原子世界。 C是光速。
a subatomic world. C is the speed of light.
G是重力强度。
G is the strength of gravity.
这里的 kB 是玻尔兹曼常数，
This kB here is Boltzmann's constant,
这与温度和热力学有关。
that's to do with temperature and thermodynamics.
这里的 M 是黑洞的质量。
And this M here is the mass of the black hole.
它甚至有圆圈，因为它里面有一个 Pi。
It's even got circles because it's got a Pi in it.
霍金的结论被证明是无可辩驳的
Hawking's conclusion proved to be irrefutable,
影响是巨大的。
and the implications are huge.
如果某物有温度，那么它就会辐射。
If something has a temperature, then it radiates.
这就是为什么如果你把手靠近热的东西，
That's why if you put your hand near something that's hot,
你能感觉到。 所以在数十亿的时间尺度上
you can feel it. And so over timescales that are billions
数十亿、数十亿、数十亿倍的时间
and billions and billions and billions of times longer
比现在的宇宙年龄，
than the current age of the universe,
射手座 A* 最终会蒸发掉。
Sagittarius A* will eventually evaporate away.
逐渐地，霍金辐射
Very gradually, the Hawking radiation
会侵蚀射手座 A*。
will erode Sagittarius A*.
越来越小。
Smaller and smaller.
直到未来数万亿和数万亿年后……
Until many trillions and trillions of years into the future...
..在最后的光芒中......
..in a final burst of light...