了解宇宙是如何运行的（2010）

How the Universe Works S06E09

Part 4 Dec. 22, 2021, 7:23 p.m.

Most chondrules condense
大多数陨石球粒
out of the cloud of hot gas
都是由太阳周围的热气云凝结而成的
around the Sun as the solar system forms.
陨石球粒被诗意地描述为
Chondrules have been described poetically
凝固的火雨滴
as droplets of fiery rain that have solidified.
它们是在我们太阳系
They are little globules of silicate melt
最早期的时候产生的硅酸盐熔体
that were produced in the very earliest history
小球体
of our solar system.
这些熔珠凝固后形成了
These globules of melt solidified to form
这些小球体
these little spheres.
它告诉了我们
It really tells us about the process of agglomeration
小物体聚集形成大物体的过程
of smaller objects to form larger bodies.
但一些陨石球粒
But some chondrules tell us
不仅告诉我们行星的诞生
not only about a planet's birth,
还告诉我们它的死亡
but also its death.
一颗叫做“gujba”的陨石
A meteorite called gujba
含有两种非常不同的球状物
contains two very different kinds of globules.
“gujba”是一种陨石
So a gujba is a type of meteorite
它的成份除了
that's made up of little spherials
硅酸盐材料的小球
of silicate material
还有铁镍金属的小球
as well as spherials of iron-nickel metal,
但在这方面它很不寻常
and it's very unusual in that regard.
我们在“gujba”中发现的这些金属球体
These metal spherials that we find in gujba are formed,
是在太阳系形成后
we think, around 5 or 6 million years
大约五六百万年形成的
after the solar system forms.
在那个时候，没有足够的热气体
At that point, there was not enough hot gas
滞留在圆盘中
lingering in the disk
以形成我们在“gujba”中看到的球粒
to form the chondrules we see in the gujba.
那么这些小球是如何形成的呢？
So how did this globules form?
真正产生这些小球的唯一途径是
The only way to really produce these globules
另一个过程
is another process,
我们认为在这种情况下，它是某种
and we think in this case it was some kind of process
类似碰撞的过程
like collisions.
强烈的碰撞使硅酸盐
Collisions so violent they vaporized
和金属汽化
the silicates and metals.
固体先变成气体，然后气体再变成液体
Solid turns to gas, and then gas to liquid.
但是什么星体含有足够的金属
But what planetary body contains enough metal to be able
来产生我们在“gujba”看到的液滴呢？
to produce the droplets we see in gujba?
只有大到能有铁核的东西
Only something big enough to have an iron core.
当一个物体变得足够大
When an object grows large enough,
它的重力变得足够强，它就会分化
its gravity become strong enough that it differentiates,
我们的意思是
and what we mean by that is,
重的东西被拉下来，沉到中心
heavy stuff is pulled down and sinks into the center,
轻的东西浮到顶部
and lighter stuff floats to the top,
所以你就有了物质的分化
so you have a differentiation of material.
地球就是一个典型的分化体的例子
Earth is a classic example of a body that has differentiated
像铁和镍这样的重金属沉入核心
Heavy metals like iron and nickel sink to the core
而较轻的岩石硅酸盐则留在地壳中
while lighter rocky silicates remain in the crust
地壳和地核
The crust and the core are separated
被称为地幔的熔融硅酸盐层隔开
by a molten silicate layer known as the mantle.
“Gujba”是一个完美的例子
Gujba is a perfect example of the fact
说明了一个事实：它有一个巨大的行星体
that you had large planetary bodies
它们分化成铁和硅酸盐
that were differentiated into irons and silicates,
它们以足够快的速度碰撞
and they were colliding at velocities
使它们的碎片再次分散到星云中
great enough to scatter their pieces
再次分散到星云中
out into the nebula again.
这让我很惊讶
That is just amazing to me,
历史上如此暴♥力♥的过程
that this really, really violent process
竟能被这些微小的碎片所捕捉
in history that's captured in these tiny little fragments.
“Gujba”揭示了
Gujba reveals the differentiated planets
早在太阳系形成后500万年
were commonplace as early as 5 million years
分化的行星就已经很普遍了
after the formation of the solar system.
在小行星带，有一个更大的线索可以证明早期分化行星的形成
小行星“普赛克(Psyche)”
小行星“普赛克”一直以来都很神秘
因为它是一个几乎由纯金属组成的巨大天体
普赛克与行星带中的任何其他小行星都不一样
那是什么呢？它是从哪里来的
每个人都有自己的专属理论
而我的专属理论有点奇怪
我认为普赛克是一次肇事逃逸碰撞的残余
一次肇事逃逸的碰撞，除去外层，只留下一个铁镍芯
普赛克实质上是一颗被粉碎的行星核心的一部分
它不可能会是其他的东西
要真正将某个东西缩小到核心
你必须击中某个东西两次，也许三次
科学家认为普赛克可能曾经是一颗原始行星
早在太阳诞生后几百万年就产生了
一颗很大的星球被分解了
现在剩下的只是地壳和地幔被破坏的残余铁心
这样的行星太多了
There were so many of these planets,
它们经常会撞在一起
they often smashed together.
如果你沿着巨大撞击形成行星的道路
If you go down this path of planet formation
走下去
by giant impacts,
最后的幸存者就是
you end up with the last survivors
一群怪物
being a bunch of freaks.
有一个这样的怪物就是我们的邻居的红色星球——火星
And one such freak is on near neighbor the red planet Mars.
为了更好地理解它
But to better understand it,
科学家需要进行另一场模拟
scientists needed another simulation,
这是一个涉及30颗行星的连环相撞的模拟
this one involving a 30 planet pileup.
当你观察太阳系的活动时
When you look at the action in a solar system,
你会发现我们最小的行星就在里面
you essentially have our smallest planet on the inside
然后从金星到地球时
and then it gets larger and larger
它会变得越来越大
as you go from Venus to the Earth,
所以你自然会认为火星会比它更大
so you would naturally expect Mars to be larger than it is.
它应该比现在大十倍，但它没有
It should be 10 times bigger than it is, but it's not.
火星的大小并不是唯一的谜团
Mars' size isn't its only mystery.
它也比我们预期的要古老得多
It's also much older than we expected.
根据一块火星陨石的化学成分
Scientists have refined the age of Mars' mantle
科学家已经确定了
based on the chemical composition
火星地幔的年龄
of a piece of martian meteorite.
在一次猛烈的撞击中，样本从行星上脱落
The sample blew off from the planet during a violent impact
并飞向地球
and made its way to Earth.
它揭示了火星是在
It revealed that Mars formed rapidly,
太阳系诞生的前200万年迅速形成
within the first 2 million years of the solar system's birth,
远远早于地球
well before the Earth.
火星很小而且火星形成的速度
Mars is small, and Mars formed really,
比它本来应该形成的速度要快得多
really fast compared to what it should have.
地球的质量是现在10倍
The Earth is 10 times more massive.
它形成于1亿年
It formed in 100 million years.
火星形成于200万年
Mars formed in 2 million years.
这说不通啊，它是我们的邻居
This doesn't make sense. It's our neighbor.
它应该看起来像我们
It should look just like us.
火星的一切感觉都不对
Everything about Mars feels wrong.
这两个谜团可能有助于相互解释
These two mysteries might help explain one another.
科学家们认为
Scientists think it's possible
在太阳系形成的前200万年里
that around 30 other similar planets
可能还有
formed alongside Mars
大约30颗类似的行星与火星一起形成
within the first 2 million years of the solar system.
那么这30个行星的连环相撞到底发生了什么？
So what happened to this 30-planet pileup?
又要玩一场宇宙池游戏了
Time for another game of cosmic pool.
所以在这个模型中，我们很快就形成了
So in this model, we very quickly form
20到30个火星大小的行星
20 or 30 Mars-sized planets.
这是一个非常拥挤的系统
This is a pretty jam-packed system.
这两颗行星之间的距离非常近
The planets are pretty close to each other,
而且正处于稳定的边缘
and it's just on the hairy edge of stability.
这群火星大小的行星迅速形成
This colony of Mars-sized planets builds rapidly.
在太阳系早期
In the early days of the solar system,
周围有足够的气体防止它们的轨道
there's enough gas around to keep their orbits
相互交叉
from crossing each other,
但2000万年后，气体消失了
but after 20 million years, the gas has gone,
它们的轨道开始相交
and their orbits start to intersect.
当它变得不稳定时
When it goes unstable,
它就会变成一个非常吵闹和混乱的地方
it's then a pretty loud and chaotic place.
当火星大小的天体相互碰撞
As Mars-sized bodies collide with each other
形成地球和金星时
to build the Earth and Venus,
我们会经历一系列巨大而猛烈的碰撞
we get a series of huge, violent collisions.
在接下来的1亿年里
Over the next 100 million years,
火星大小的原行星♥相♥互湮灭
the Mars-sized protoplanets annihilate each other
最终形成第二代行星