了解宇宙是如何运行的（2010）

How the Universe Works S01E07

Part 5 April 18, 2021, 7:57 p.m.

and a few of them are quite interesting.
其中一个是地球质量的两倍
There's one that's only
about twice the mass of Earth.
它离恒星非常近
Now, that particular one...
is very close to the star.
大概太热了, 生命不可能存活
It's probably very
hot, too hot for life.
但另一个的质量大约是地球的八倍
But there's another one, about
eight times the mass of the Earth,
离恒星的距离足够远
which is getting far
enough away from the star
哪里也许适宜居住
that it might be in the habitable zone.
这颗行星的轨道跟地球很相似
Like Earth, this planet
orbits at a distance
令它拥有液态水
where water is a liquid.
有水就可能有海洋和生命
And where there's liquid water,
there could be oceans and life.
2009年3月, 太空总署发射了…
In March 2009, NASA launched
开普勒太空望远镜
the Kepler Space Telescope.
任务是在新太阳系中…
Its mission, to search for planets
搜寻与我们相似的行星
similar to our own in new solar systems.
也许会发现有沼气大气层的行星
We may find planets that
have methane atmospheres...
或者有氨气大气层的行星
that have ammonia atmospheres.
或许找到覆盖着重质有机物的行星
We may find planets that are
covered in heavy organics...
一种柏油状物质
a tar-like materia
或许找到一些有水覆盖的行星
We may find some that
are covered by water.
未来10至20年间的一项重大探索
I think one of the glorious quests
here in the next decade or two
就是了解宇宙中可能存在的…
is to learn the full diversity of
the family of Earth-like planets
整个类地行星家族
that may be out there in the universe.
天文学家预计利用开普勒望远镜
With Kepler, astronomers expect to
discover hundreds, possibly thousands,
有可能发现数百或数千个新太阳系
of new solar systems.
以银河系为例
Think about our own Milky Way galaxy.
它有5000亿至1万亿颗恒星
The galaxy has roughly 500
billion to a trillion stars.
相当大部分恒星拥有行星
Some fairly large percentage
of that have planets.
想想有多少个已知的星系
Now, think about how
many galaxies we know of.
我们肯定还没发现宇宙中所有星系
We certainly haven't found all
the galaxies in the universe yet.
但我们拍摄到的星系已有600亿个
But the ones we can take a picture of
are actually about 60 billion galaxies.
当你今晚抬头仰望星空
When you look up at
the night sky tonight,
仅在视线范围内
simply in the path of your sight,
即使肉眼无法看到
even if you can't see it,
也存在着数十亿个太阳系
there are billions of solar
systems all around you.
很可能有一个太阳系
And there could be a solar system
也拥有像地球一样的行星
with a planet just like Earth.
发生过一次就有可能发生第二次
If it happened once,
it could happen again.
太阳系不会永远存在
Solar systems don't last forever.
轨道会瓦解, 行星会相互碰撞
Orbits fall apart. Planets collide.
这也许会发生在我们的太阳系
It might happen to us.
即使不发生, 在50亿年后…
But even if it doesn't, in
another five billion years,
一场大灾难也会结束我们的太阳系
a catastrophe will end our
solar system as we know it
没有甚么是永恒的, 包括太阳系
Nothing lasts forever,
not even solar systems.
我们的太阳系现在看似稳定
Ours may seem stable now,
但其实它正在慢慢瓦解
but, actually, it's
very slowly coming apart.
若太阳系的过去是混乱的
If the solar system
was chaotic in the past,
不表示它现在已完全安定下来
that doesn't mean its
all settled down now.
未来仍然可能出现混乱局面
There is still a possibility of a
little bit of chaos in the future.
在未来, 行星彼此间的引力
In the future, the gravitational
pull of the planets on each other...
会逐渐打乱它们的轨道
will gradually disrupt their cubits.
也许在数十亿年间
Perhaps, over the billions of years...
行星会在引力作用下相互推撞
the planets will jostle each
other in this gravitational way
最终两个行星会相互靠近
so that, eventually, two of the
planets will come close to each other.
当这种情形发生时
When that happens, and it will...
两个行星会绕着对方转动
those two planets will engage
in a sort of a do-si-do;
一个或两个会被掷入偏远的轨道
flinging one or the other of
them, maybe both, into wild orbits,
甚至有可能被弹出太阳系
perhaps ejecting one or both
of them from the solar system.
火星也许会被抛出太阳系
Mars could be thrown
out of the solar system
水星也许会撞入地球
and Mercury might crash into the Earth.
整个纸牌搭的房♥子, 即是太阳系
The entire house of cards
that is our solar system
会完全瓦解
would completely fall apart.
所有太阳系的诞生和死亡
Solar systems begin and end
都伴随着大量的碰撞和毁灭
with a lot of collisions
and destruction.
但暂时毋须恐慌
But don't panic yet.
这些都是数十亿年以后的事
This is gonna take billions of years.
但在太阳系的有生之年
But over the lifetime
of the solar system,
这些都是会发生的不测事件
these are eventualities
that could come to pass.
不管怎样, 我们的太阳系定会毁灭
But one way or another,
our solar system is doomed.
像所有太阳系, 当中心恒星灭亡时
Like all solar systems,
the end will come
末日就来临了
when the star at the centre dies.
50亿年后, 我们的太阳
In five billion years, our own star
将会耗尽燃料变成一个红巨星
will run out of fuel
and become a red giant
温度会升高, 体积会膨胀
It'll heat up, swel
并将吞噬所有内行星
and engulf the inner planets.
地球表面会被烧焦
The Earths surface will be scorched.,.
海洋会蒸发
the seas will evaporate...
陆地会熔化
and the land will melt
太阳会膨胀直至到达地球的轨道
The sun will become about as
big as where the Earth's orbit is
所以世界末日的景象可能是
so a likely scenario
for the end of the world
我们会短暂地进入太阳
is that we're going to be
inside the sun for a while.
地球会被太阳吞噬
The Earth's gonna get
swallowed right up into the sun
会被烧烤, 蒸发
and it's gonna be
toast, vapour, literally.
没多久红巨星也会瓦解
After a while, the red
giant will fall apart, too,
剩下微小的恒星残骸: 白矮星
leaving behind a tiny corpse
of a star called a white dwarf.
白矮星的体积与地球相若
It will be about the size of the Earth
但它要经过数百万年甚至数十亿年
and it will cool off
才能冷却下来
over many millions or billions of years.
这将是我们的太阳系的最终结局
That will be the real
end of our solar system.
从这个死寂的地球…
From the Earth, this dead, rocky planet
它曾经怀有一个充满生气的文明
that used to harbour an
enormously vibrant civilisation,
我们向外看
we will look out,
太阳变成了一个非常苍白的小点
and there will be this fairly
faint dot which is our sun,
一颗奄奄一息的白矮星
now a white dwarf, a
dying, almost dead star.
内行星的残骸会继续绕白矮星运行
The remains of the inner planets will
continue to orbit the white dwarf.
但巨大外行星会完好地继续存在
But the giant outer planets
will live on7 untouched.
在太阳成为红巨星时
They will have warmed up
它们的温度会升高
during the red-giant phase of the sun.
但一旦太阳变成白矮星
But once the sun is a white dwarf,
这些巨行星就会照样生存下去
those giant planets will
survive just as well,
保留着它们的氢气和氦气
holding on to their hydrogen and helium,
虽然温度将比以前低
albeit colder than they used to be,
因为白矮星不能给它们提供热力
because that white dwarf will
no longer be warming them up.