宇宙时空之旅（2014）

Cosmos: A SpaceTime Odyssey S01E13

Part 3 April 25, 2021, 12:41 p.m.

薇拉·鲁宾已经证实了
Vera Rubin had verified the existence
一个全新的更为广阔的宇宙的存在
of a new, much larger cosmos.
正如我们以为已经了解的那个宇宙一样
And just like the one we thought we knew,
新宇宙充满了神秘
it was filled with mystery.
暗物质完全无法观测
Dark matter is completely unobservable,
只是它的引力效应
except for its gravitational effect,
能使可见的恒星和星系运动得更快
which makes visible stars and galaxies move faster.
它的本质是一个更深邃的奥秘
Its nature is another deep mystery.
鲁宾为一个不可见宇宙的存在提供了证据
Rubin had provided the evidence for an invisible universe
它的质量几乎是我们
nearly ten times more massive
自认为已知的宇宙的十倍
than the one we thought we knew.
这就像我们夜里站在海边
It was as if we had been standing on the seashore at night,
错误地认为
mistakenly believing
波涛卷起的泡沫就是整个大海一样
that the froth on the waves was all there was to the ocean.
薇拉·鲁宾仰望夜空中点点星光
Vera Rubin looked at the stars and realized
意识到它们不过是波涛卷起的泡沫
they were merely the foam on the waves,
而浩瀚的海洋尚为未知
and that the greatest part of the ocean remained unknown.
不过别急
But wait.
还有更疯狂的
It gets crazier.
我们银河系中
Our Milky Way Galaxy,
有几千亿颗恒星
a few hundred billion stars,
加上气体云和尘埃
plus the clouds of gas and dust,
这些恒星的遗骸和原料
the stuff of once and future stars--
以及大约一千亿个其他星系全部一起
and about a hundred billion other galaxies-- all of that,
包括那些数不胜数的千万亿颗
including those uncounted billions of trillions
行星卫星和彗星
of planets, moons, and comets--
只相当于宇宙物质总量的百分之五
amounts to only five percent of what is actually there.
因为比起暗物质
Because there's a bigger unsolved mystery
还有一个更大的未解之谜
than dark matter--
暗能量它在宇宙中所占的比重更大
Dark energy, which makes up even more of the cosmos
也是宇宙膨胀的推动力
and drives its expansion.
弗里茨·兹威基发现的超新星爆发
And it was Fritz Zwicky's supernovas
照亮了通往揭示其存在的道路
that lit the way to the revelation of its existence.
在某些情形下
In one scenario,
一颗恒星在消耗完其核燃料后...
a star consumes all of its nuclear fuel...
会冷却下来
then cools,
然后突然在自身引力作用下坍缩
and suddenly collapses under its own gravity.
最后在一次巨大的爆发中反弹出来
The star rebounds in a massive explosion,
留下一颗中子星或一个黑洞
leaving behind a neutron star or a black hole.
由于恒星质量的大小
Since the mass of the original star
可能有很大不同
can fall within a wide range,
在超新星爆发时的最大亮度
its peak brightness as a supernova
也会有很大不同
can also vary widely.
因此只通过其亮度
So, you can't tell how far away it is
我们不能判断出它的距离
just from how bright it looks.
一个相对较近的超新星爆发看起来可能
A relatively nearby supernova might appear just as bright
和一个更远的但能量更高的一样亮
as one that was more powerful, but farther away.
不过有一种超新星爆发
But there's another kind of supernova
它只会有一种强度
that comes in only one strength.
那就是巨星和矮星
It marks the violent grand finale
所跳探戈舞的狂暴结局
of a tango danced by a giant star and a dwarf.
当这样两颗恒星♥相♥互绕转且距离很近时
As the two stars orbit closely around each other,
巨星将其外层气体抛向矮星
the giant sheds its outer layers of gas onto the dwarf.
当这些额外的质量到了矮星无法承受时
When the added weight becomes too much for it to bear,
它就会像一颗巨大的热核炸♥弹♥一样爆♥炸♥
the dwarf detonates like a stupendous thermonuclear bomb.
数周之内
For a few weeks,
这一超新星爆发的亮度足以匹敌
the brilliance of such a supernova rivals
其所在星系所有恒星亮度之和
the combined light of all the stars in its galaxy.
这种超新星爆发
This kind of supernova
其最大亮度总是相同的
always has the same maximum power output,
大约是我们太阳亮度的五十亿倍
about five billion times brighter than our Sun.
用足够大的望远镜
With big telescopes,
我们可以在非常遥远的星系中看到它们
we can see them in galaxies very far away,
甚至是在可观测宇宙的边缘
out toward the edge of the observable universe.
因为这种超新星爆发都有相同的亮度
Because all such supernovas have the same wattage,
它们是测量宇宙中遥远距离的
they're ideal tools for measuring distances
理想工具
to the farthest reaches of the universe.
我们把它们称为"标准烛光"
We call them "standard candles."
1929年爱德温·哈勃发现了
In 1929, Edwin Hubble discovered
宇宙正在膨胀
that the universe is expanding.
遥远星系正在相互远离
The distant galaxies are drifting away from one another.
后来我们知道了
Later, we learned
早在140多亿年前
that the expansion began
宇宙膨胀就已经开始了
some 14 billion years ago
它伴随着宇宙的诞生大爆♥炸♥
with the explosive birth of the universe-- the Big Bang.
人们都以为
Everybody assumed
宇宙膨胀的速率会减慢
that the rate of expansion would be slowing down,
因为宇宙各个部分都有
due to the mutual pull of gravity
相互的引力作用
between all the parts of the universe.
如果有足够多的暗物质
If there is enough dark matter,
其引力最终将使宇宙膨胀停止
its gravity would eventually bring the expansion to a stop,
然后宇宙将会开始收缩
and the universe would then fall back on itself.
如果是那样的话宇宙最终将经历一次
In that case, everything would eventually collapse
大坍缩
in a Big Crunch.
另一种情形如果宇宙中暗物质较少
On the other hand, if the universe had less dark matter,
那么宇宙将会永远膨胀下去
the expansion would continue forever,
只是会变得越来越慢
just getting slower and slower.
当时有两队相互竞争的天文学家
Two competing teams of astronomers
正在观测遥远星系的那些超新星爆发
were observing those supernovas in distant galaxies.
结果却是又一个
It turned out to be another one
不可思议的发现
of those "that's funny" moments.
1998年两个小组独♥立♥地得到了相同结论
In 1998, both teams independently came to the same conclusion.
宇宙膨胀不但没有减速
The expansion isn't slowing down at all...
反而在加速
it's speeding up.
这意味着宇宙将永远膨胀下去
This means the universe will continue to expand forever.
宇宙中似乎有一股神秘的力量
There seems to be a mysterious force in the universe,
在最大尺度上超越了引力作用
one that overwhelms gravity on the grandest scale
促使宇宙不断膨胀
to push the cosmos apart.
宇宙中的大部分能量
Most of the energy of the universe is bound up
都跟这一未知力量密切相关
in this unknown force.
我们把它称为"暗能量"
We call it "dark energy,"
但这一名称就像"暗物质"
but that name, like "dark matter,"
只是因为我们对其无知而起的代号♥罢了
is merely a code word for our ignorance.
不知道所有的答案也不是什么坏事
It's okay not to know all the answers.
与其相信可能错误的答案
It's better to admit our ignorance
不如直接承认我们的无知
than to believe answers that might be wrong.
不懂装懂的行为只会
Pretending to know everything closes the door
关闭探索事实真♥相♥的大门
to finding out what's really there.
今晚我们的航船将驶入更为奇异的水域
Tonight, our ships sail Into even more exotic waters.
跟我来吧
Come with me.
人类只有两艘飞船
Only two of our ships have ventured
驶入了星际间浩瀚的暗海
into the great dark ocean of interstellar space.
这一历史上最漫长的旅程
The longest odyssey in all of history
于1977年启动
was launched back in 1977--
它们是美国宇航局的旅行者一号♥和二号♥
NASA's Voyager 1 and 2.
旅行者号♥以每小时六万多千米的速度飞行
The Voyagers move about 40,000 miles an hour.
它们让我们第一次近距离观测木星大红斑
They gave us our first close-up look at Jupiter's great red spot,
那是一个大小为地球三倍的飓风
a hurricane three times the size of Earth
从它最早在16♥4♥4年第一次被观测到时起
and one that's been raging since at least 16♥4♥4,
它就一直在木星表面肆虐
when it was first observed.
据我们所知它可能已经存在了上千年
For all we know, it could be thousands of years old.
在木卫一上旅行者号♥首次发现了
The Voyagers discovered the first active volcano on another world,
另一颗星球上的活火山
on Jupiter's moon Io...
在木卫二冰层下发现的海洋
and an ocean beneath the icy surface of the moon Europa...
其储水量至少是地球上总水量的两倍
with at least twice as much water as we have here on Earth.
旅行者号♥飞越了土星环
The Voyagers dared to fly across Saturn's rings
发现该环是由上百条细带构成的
and revealed that they were made of hundreds of thin bands
细带中都是围绕土星运行的雪球
of orbiting snowballs.
在巨大的土卫六上
On Saturn's giant moon Titan,
旅行者号♥检测到大气的存在
Voyager detected an atmosphere