了解宇宙是如何运行的（2010）

How the Universe Works S06E09

Part 3 Dec. 22, 2021, 7:23 p.m.

This is exceptionally fast on cosmic-time scales.
这意味着
What this means is that you take the entirety
你把所有重叠的物体
of that overlapped population of bodies,
粉碎成更小的碎片
and you smash them up into smaller debris.
木星就像是一个拿着锤子的小孩，你知道吗？
Jupiter is like a little kid with a hammer, you know?
它就这么进来了，然后到处乱撞
It just comes in and is whacking around at everything,
把太阳系内部搞得一团糟
and it's making a mess of the inner solar system.
这是一场打了类固醇的宇宙泳池游戏
It's a game of cosmic pool on steroids.
让我们从木星开始
Let's start with our Jupiter,
模拟我们的太阳系模型
for our model here of the solar system.
它所清扫的这些碎片之间
It's causing a bunch of very violent collisions
产生了一系列非常剧烈的碰撞
between all of this debris that it's sweeping up.
这些巨大的碰撞产生了
These huge collisions are making an enormous amount
大量非常小的物质
of really small material,
由于太阳周围气体的阻碍
which can drift really fast inward in the solar system
这些物质可以在太阳系内快速向内漂移
due to the drag from the gas around the Sun.
这些星子不断碰撞
These planetesimals collide over and over,
被粉碎成碎石大小
pulverized to the size of gravel.
对于较小的碎片来说，撞击太阳周围稠密的气体云
For the smaller debris, hitting this dense gas cloud
就像撞上了逆风
around the Sun is like plowing into a headwind.
碎石群失去了动力
The swarm of rubble loses the momentum that keeps it
无法保持在太阳轨道上
in orbit around the Sun and starts spiraling in,
开始盘旋，但遇到了障碍
but it hits roadblocks.
因此，当所有这些碎片以巨浪的形式向内冲时
So as all this debris rushes inward in a big wave,
它们会被拉进去，直到被卡在超级地球后面
it gets dragged in until it gets stuck behind the super-Earths.
碎片不断堆积，直到超级地球最终坍塌
Debris builds up until the super-Earths finally give way.
超级地球就像一座大坝
The super-Earths are like a dam
无法抵挡水流的冲击
that can't quite resist the flow of water
开始开始后退
and begins to recede and eventually gets
最终被推到太阳表面
kind of pushed onto the surface of the Sun,
碰撞碎片的流动也随之发生
together with the flux of collisional debris.
这是一个非常迅速的过程
It's a remarkably swift process.
在2万年之内，所有的超级地球都会撞向太阳
In just 20,000 years, all the super-Earths crash into the Sun.
在内太阳系
After the dramatic evolution
戏剧性的演变之后，只剩下了
of the inner solar system, there's only a fraction
原始质量的一小部分
of the original mass left.
太阳系是过去的一个幽灵
The solar system is a ghost of what it used to be.
距离太阳的3900万英里以内
There's nothing in the first 39 million miles
什么都没有
from the Sun.
但稍远一点的地方
But slightly farther out,
有一个狭窄的岩石碎片环
there's a narrow ring of rocky debris,
大约10%的原始物质被木星卷进来
about 10% of the original material swept in by Jupiter,
刚好足以重建太阳系内部
just enough to rebuild the inner solar system.
一些幸存者，小星子开始重组
A few survivors, small planetesimals start to regroup.
经过数百万年
Over millions of years,
形成了四颗小型岩石行星
four small, rocky planets form.
水星、金星、地球和火星
Mercury, Venus, Earth, and Mars
就是由这些残余物形成的
form from this leftover debris.
我们所站的行星
The planet that we're standing on may not be
可能不是太阳系的第一代行星
an original generation solar system planet.
这有点像用煤渣块建造一座房♥子
It's kind of like building a house with cinder blocks
这座房♥子坐落在那个地方，但后来被拆除了
from a house that sat on that spot but was demolished.
我们不仅呼吸着早已消亡的恒星的大气
Not only are we breathing the atmospheres of long-dead stars,
我们脚下的岩石
the rock beneath our feet
也可能来自早已消亡的行星
could have been from long-dead planets.
所以地球可能是第二代行星
So Earth could be second-generation planet
由大袭击的残骸形成的
formed from the wreckage of the grand attack.,
但是有一样东西被超级地球
But there was one thing the super-Earths
带进了他们炽热的坟墓……
took with them to their fiery grave...
太阳系内部
The supply of hydrogen and helium
氢和氦的燃料
in the inner solar system.
当你现在观察地球的大气层
When you look at the Earth's atmosphere now,
其中没有任何氢或氦
we don't have any hydrogen or helium in it.
内部行星形成的圆盘中
There was hydrogen and helium in the disk
有氢和氦
where the inner planets formed,
但它们成为了第一代行星
but that became part of the super-Earths,
“超级地球”的一部分
the first generation planets.
当木星进入并将它们送入太阳时
When Jupiter came in and dropped them into the Sun,
它们也带走了它们的氢和氦
they took their hydrogen and helium with them.
所以现在你周围空气的成份
So the composition of the the air around you right now
可能就为我们是第二代行星
may be due to the fact
提供了事实依据
that we're a second-generation planet.
所以，我们现在认为的地球实际上是地球2.0
So the earth we now consider home is in fact is Earth 2.0,
“第二”听起来可能不太好
And being second might not sound great
但也许这个“第二”就是我们在这里的原因
but maybe being second is the reason we are here.
地球的大气层是一种丰富的混合气体
Earth's atmosphere is a fertile blend of gases
让我们所知的生命得以繁衍
that allows life as we know it to flourish,
如果地球是第一代行星
an atmosphere that might have been completely different
这种大气层可能会完全不同
if Earth was a first-generation planet.
完全有可能的是，像我们这样的生命
It's entirely possible that life, like us,
首先必须得有一个
needs to have a second-generation planet
第二代的行星出现
to arise in the first place.
我们的星球会比我们想象的
Could our planet be more unusual
更不寻常吗？
than we'd ever thought?
地球在宇宙环境中有多特别？
How special is the Earth in a cosmic setting?
我们真的不知道这个问题的最终答案
We don't really know the final answer to this question,
但证据开始指向一个事实
but evidence is beginning to point to the fact
即地球实际上是一种稀有的星球
that the Earth is actually kind of rare,
我们真的应该珍惜我们的星球
and we should really appreciate our planet.
找出太阳系发生了什么
Finding out what happened to our solar system
就像研究宇宙犯罪现场
is like studying a cosmic crime scene.
为了揭示太阳系的神秘历史
To reveal the solar system's secret history,
我们需要去一些不寻常的地方
we need to look in unusual places,
我们的家园诞生于
the last surviving pieces of the violence
暴♥力♥事件后残存部分
from which our home was born.
我们的太阳系是一个天然的悬案现场
Our solar system is a celestial cold case,
隐藏着它的过去，它的狂暴的痕迹
and it's hiding the traces of its violent past.
你现在看到的是一个干涸的犯罪现场
What you have now is a crime scene that has dried up,
而你却在试图寻找一些蛛丝马迹
and you're trying to find little clues as to
来了解45亿年前发生了什么
what happened 4 1/2 billion years ago.
这是一个非常非常难解决的问题
It's a really, really difficult problem to solve.
确凿的证据可能很难找到
Solid evidence could be hard to find,
但有时我们很幸运
but sometimes we get lucky.
我们没有时光机，所以很难回到
We don't have a time machine, so it's hard to go back
45亿年前
in time 4 1/2 billion years
去观察那时的太阳系，看看它当时在做什么
and look at the solar system and see what it was doing back then.
然而，有时关上门却会打开一扇窗
However, sometimes nature provides,
如果你没有时间机器
and if you don't have a time machine,
有时时间胶囊也可以做到
sometimes a time capsule will do just as well.
事实上，我们有
And in fact, we have time capsules
早期太阳系的时间胶囊
of the early solar system,
我们称它们为陨石
and we call them meteorites.
大多数陨石是坠落到地球上的
Most meteorites are chunks of asteroids
小行星的碎片
that fall to Earth.
根据它们的来源
Depending on their origin,
它们有不同的形状和大小
they come in different shapes and sizes.
小行星就像太空化石
Asteroids really are like space fossils
因为它们是45亿年前形成的
because they were formed 4 1/2 billion years ago,
但它们基本上是死亡的
but they've basically remained dead.
它们也是残余物，是行星形成的残余物
They are the leftovers, the remnants of planet formation.
它们是最后还没有变成行星的一小部分
They're the last little bits that haven't become planets yet.
为了理解为什么陨石是如此有用的线索
To understand why meteorites are such useful clues,
我们首先需要知道行星是如何形成的
we first need to know how planets form.
这个过程叫做吸积
It's a process called accretion.
围绕太阳旋转的热气云
The cloud of hot gas swirling around the Sun condenses
凝结成越来越大的天体
and clumps into larger and larger bodies.
我们在陨石中发现了这一过程的痕迹
We find traces of this process inside meteorites,
在被称为陨石球粒的微小矿物珠子中
in tiny mineral beads called chondrules.
陨石球粒是太阳系
Chondrules are literally the seeds
所有结构的种子
of all of the structure in our solar system.
当太阳系形成时