了解宇宙是如何运行的（2010）

How the Universe Works S05E09

Part 6 April 18, 2021, 7:48 p.m.

If a type of Dyson sphere
是围绕着塔比之星建造的
is being constructed around tabby's star,
那么它的工作人员显然是非常安静的
its workforce is suspiciously quiet.
每一个重大的猜想都需要有力的证据
WoEvery big claim requires big proof.
看到光的变化就很有趣
Just seeing a change in a light profile
但这只是很有趣
is interesting and is intriguing
但不是令人信服
but is not compelling
对我们来说这还不是证据
and is not evidence to me yet.
我想这是告诉我们
I think that just tells us
我们必须继续寻找，继续学习
we have to keep looking and keep learning.
我希望它是外星人
I would love for it to be aliens.
这样，我的工作就有保障了
That would be job security for me.
但说实话，我还是尽量现实一点
But honestly, I'm trying to be realistic about this.
但是，如果不是外星人改变了星球的用途
But if it's not aliens repurposing a planet,
还有什么可能导致光线急剧变暗呢
what else could be causing the dramatic dimming in light?
有可能是恒星活动导致的吗？
Could it be stellar activity?
可能是恒星周围有个碟状物吗？
Could it be there's a disc around the star?
会不会是解体的行星？
Could it be disintegrating planets?
现在看来，最在可能性
But probably, right now, the leading contender
是一系列围绕这颗恒星运行
is a family of comets which are orbiting this star
并导致这些亮度变暗的彗星
and causing these dips.
彗星是行星系统形成后留下的
Comets are vast, dirty snowballs left over
巨大、肮脏的雪球
from the formation of planetary systems.
但如果塔比星周围
But if a giant cluster
存在一个巨大的彗星团
of comets exists around tabby's star,
它们的可能性会显得更大
they could appear a whole lot bigger.
如果它们靠近它们的恒星
If they get close to their star,
这些冰就会升温
that ice can heat up,
变成气体并膨胀
turn into a gas and expand.
不断膨胀的云团
And that expanding cloud
比行星还要大得多
can then be much larger than a planet.
我们在自己的太阳系中
We see that in our own solar system.
就能看到这一现象
And it could be something like that that's blocking the star.
这是有道理的
It makes sense.
它解释了我们看到的很多东西
And it explains a lot of what we're seeing.
但这并不能解释我们所看到的一切
But it doesn't explain everything that we're seeing.
巨大的彗星云
A vast cloud of comets could be
可能挡住了塔比星的光线
blocking the light from tabby's star.
但有一个问题：不太可能有足够的彗星
But there's a problem: It's unlikely there would be enough
来解释这些亮度的下降
comets to account for these dips.
而且红外信♥号♥♥
And the infrared signature
也没有什么异常
hasn't been anything out of the ordinary.
所以可能我们错过了什么
So either we've missed it.
要么尘埃的扩散相对较快，这是很有可能的
That dust disperses relatively rapidly, which is possible,
或者说除了彗星的解体
or there's something more going on here
还有其他的原因
than just comets breaking up.
目前的理论
None of the current theories
都不能完全解开塔比星的奥秘
can fully solve the mystery of tabby's star.
所以，目前
So for now, an alien megastructure built
一个由行星建造的外星巨型结构
from a planet remains an intriguing
仍然是一个有趣的遥远设想
if distant possibility.
我们已经看到了由钻石构成的世界
We've seen worlds made of diamond, planets
以及行星上的铁水从天上倾泻而下
where molten iron rains
也许现在
from the sky and, perhaps now,
这是外星人智慧的第一个迹象
the first signs of alien intelligence.
但银河系中还有一颗行星
But there's another planet in the galaxy
可能是其中最怪异的
that could be the weirdest of them all,
因为，无论我们多么努力寻找
because, no matter how hard we look,
我们根本找不到另一颗与之匹配的行星
we simply can't find another to match it.
我们对系外行星的搜寻
Our hunt for exoplanets
揭示了一个现象
has revealed a galaxy filled
银河系充满奇异的行星系统
with bizarre planetary systems
和奇异外星世界
and strange alien worlds.
但最令人惊讶的是
But the biggest surprise is how few of these worlds
这些世界中很少有像我们的星球，地球
look like our planet, the earth.
到目前为止，我们还没有发现很多
So far, we haven't found many, if any, solar systems
和我们的太阳系完全相同的太阳系，如果有的话
that are kind of identical to ours.
我们总是假设里面有小行星，外面有大行星
We always assumed there'd be small planets
比如我们的太阳系
on the inside, big planets on the outside like ...
我们找不到太多这样的星系
like our own solar system. We don't find too many of those.
我们发现
What we have found is that
围绕其他恒星最常见的行星类型
the most common type of planet around other stars
是所谓的“超级地球”
is what's called a super earth.
这些超级地球
These super earths
都有着厚厚的大气层
have atmospheres that are too thick,
产生的压力太高，无法支持我们这样的生命
creating pressures too high to support life like us.
那么，为什么我们这个
So why does our small planet,
有着裸♥露♥的大♥陆♥和相对稀薄的大气层的小行星
with its exposed continents and relatively thin atmosphere,
显得如此罕见呢？
appear to be so rare?
一个全新的、激进的观点认为
A new, radical idea suggests the earth
地球可能是第二代行星
could be a second-generation planet,
由曾经主宰早期太阳系的
built from the remains of a demolition derby
巨大岩石世界之间
between giant rocky worlds
一场毁灭竞赛的遗迹建造而成
that once dominated the early solar system.
在我们所知的这些行星之前
WoThere may have been planets before the ones
或许存在着被撞飞出去
we know that were destroyed,
或者直接飞向太阳的行星
that were kicked out or sent careening into the sun.
地球因此成为了第二代行星
That makes the earth a second-generation planet.
我们可能有一些
We may have had brothers and sisters
我们从来不知道的兄弟姐妹
that we never knew about.
想象一下场景。。。46亿年前
Imagine the scene ... 4.6 billion years ago,
我们太阳系中的行星
the planets in our solar system begin to form
开始由巨大的尘埃和碎片组成
from a vast disc of dust and debris.
巨大的木星是第一个形成的
Giant Jupiter is the first to form.
进入一个遥远的轨道
And it settles into a distant orbit.
今天地球所在的地方
Where the earth sits today,
诞生了一系列超级地球
a band of super earths are born,
它们是地球质量10倍的广阔世界
vast worlds up to 10 times the mass of the earth
有着厚厚的粉碎性大气
and with thick crushing atmospheres.
这些巨大的、不适宜居住的星球
The gravity of these giant,
它们的引力
inhospitable worlds dominates
主宰着太阳系内部
the inner solar system,
阻止了较小的
preventing smaller, earth-sized planets
地球大小的行星的形成
from forming...
也就是说，直到木星加入这一行列
That is, until Jupiter joins the party.
我们相信，这些第一代行星
We believe that this first generation of planets
由于受到了太阳系的大霸王的
was driven
木星的引力的牵引
onto the surface of the young sun
被驱赶到了
by the migration of our big bully
年轻的太阳表面的
in the solar system ... Jupiter.
太阳系诞生的几百万年后
A few million years
由于原行星盘引力的驱动
after the birth of the solar system,
导致了
the gravity of the protoplanetary disc
木星的减速
slows Jupiter down.
它开始向太阳旋转
And it starts to spiral in towards the sun.
当它向内移♥动♥时
As it moves inwards,
它将小行星和碎片的波浪
it pushes waves of asteroids
推向了这些超级地球
and debris towards the super earths.
进入的碎片
The incoming debris disturbs
扰乱了巨大行星的轨道
the orbits of the giant planets.
有些行星可能互相残杀
Some may smash each other to pieces.
而有些行星被送到太阳表面
Others are sent hurtling into the sun.
一旦行星大屠♥杀♥结束
Once the planetary carnage is over,
木星就会
Once the planetary carnage is over,
被新形成的土星的引力拖出
by the gravity of the newly formed saturn.
留下来的太阳系
The solar system that is left behind is a place
是一个耗尽了固体和气体物质的地方
that's depleted in solid material and gaseous material.
就在这个地方
It is a place where ...
经过数亿年的时间
where debris will coalesce
碎片慢慢地聚合
over hundreds of millions of years
并最终形成我们今天所拥有的