了解宇宙是如何运行的（2010）

How the Universe Works S10E04

Part 2 Aug. 5, 2022, 5:04 p.m.

as the now molten earth
began to form anew.
[拉德鲍]现在，我们可以大致描绘出
[Radebaugh] Now, we can
kind of paint a picture
这些大块岩石可能来自哪里
of where these big lumps
of rock might have come from.
他们非常古老
They're very old.
事实上，它们与那次大碰撞事件的年龄相同
They're, in fact, the same age
as that large impact event.
它们可能是忒伊亚的碎片
They could be pieces of Thei
忒伊亚的巨大板块沉入到我们的星球核心……
The giant slabs
of Theia sink down
into our planet...
……几十亿年都没有被发现
...and lie undiscovered
for billions of years.
地球在两个星球的毁灭中重生
Earth reforms from the ruin
of both planets.
现在，你可能会认为这样的碰撞是毁灭性的
Now, you might think
that a collision like this
is just devastating,
没有任何好处
there's no upside at all,
但这次碰撞产生的一些东西
but there's some
things that came out
of this collision
可能会导致生命存在的可能性
that may have led
to the possibility of life.
当这两颗行星结合时
When these two
planets combined,
忒伊亚的部分铁核与地球的铁核合并
parts of Theia's iron core
merged with Earth's.
所以，这意味着地球收集了一个
So, that means that Earth
collected a much bigger core
比它自己拥有的更大的地核
than it might have
possessed on its own.
这对我们来说是个好消息
This is good news for us
因为地核是磁场的来源
because the core is the source
of the magnetic field
后者保护着我们
that protects us.
地核中流动的液态金属
Liquid metal
flowing around
in the outer core
产生了地球的磁场……
generates Earth's
magnetic field...
是抵挡太阳风的保护层
...a protective shield
from the Sun.
[塞勒]实际上，太阳的每一次打嗝
[Thaller] The Sun can actual
output billions of tons
就能产生数十亿吨♥的高能质子和电子
of high-energy
protons and electrons
in a single burp.
这些都将剥离我们的大气层
That, eventually, would hav
stripped away our atmosphere
如果没有活跃的地核和磁场
If it weren't
for that active core
我们就会像火星一样
and that magnetic field,
只是一片光秃秃的
we would look like Mars,
了无生机的沙漠
just sort of a bare
and barren desert.
多亏了忒伊亚的额外铁元素
Thanks
to Theia's extra iron,
地球熔化的外核很大……
Earth's molten
outer core is large...
……所以它冷却地很缓慢
...so it cools slowly,
保持着熔融状态
staying molten,
并不断产生强大的屏蔽磁场
and keeps on generating
a strong magnetic shield.
[塞勒]因为碰撞
[Thaller]
Because of that collision,
就有了额外的铁，额外的热
the extra iron,
the extra heat,
我们一直保持着活跃
we've stayed active.
我们就有了一个磁场
We have a magnetic field.
我们被保护起来
We are protected,
事实上，这也是我们在这里谈论这件事的原因
and, in fact, that's why we're
here talking about it.
灾难性的影响通过另一种方式帮助了生命
The catastrophic impact
helped life in other ways.
[沃尔什]忒伊亚事件绝对是巨大的
[Walsh] The Theia event
was absolutely huge,
绝对不是一个100英里的小行星在沙漠中撞出大陨石坑所产生影响可比
and not an impact like
a 100-mile asteroid making
a big crater in the desert,
这是行星撞击地球
but a planet hitting a planet,
造成了一个巨大的碎片环在地球上方展开
causing a huge disk of debris
spread out from the earth,
并最终形成了月球
out of which formed the Moon
碰撞后
After the collision,
地球倾斜角度之大
the earth tilts on its side
旋转速度之快令人难以置信
and spins incredibly fast.
一天只有几个小时
A day only lasts a few hours
地球本身轻微地向一侧旋转
The earth itself rotates
slightly on its side,
如果任其自行运转
and, if left to its
own devices,
实际上会经历不可预测的、混乱的摆动
would, in fact,
experience unpredictable,
chaotic wobbling.
月球的存在
The fact that the Moon
is there
稳定了地球
stabilizes the earth,
稳定了气候
stabilizes our climate.
月球对海洋的引力
The Moon's
gravitational pull
on our oceans
产生了潮汐，减慢了地球自转的速度……
creates tides and slows
down the earth's spin...
……创造一个为生命准备的世界
...creating a world
primed for life.
我们实际上要感谢月球和它的祖先忒伊亚
We actually owe quite a bit
to the Moon and Theia,
因为它们
its progenitor,
让地球成为了一个适合生命生存的星球
for making Earth
a hospitable planet
for life.
[萨特]45亿年前的一次巨大碰撞
[Sutter] A giant collision
4.5 billion years ago
听起来像是一场灾难
sounds like a catastrophe,
但它可能是地球上发生的最好的事情
but it was probably the best
thing to happen to the earth.
忒伊亚，我要握住你的手
Theia, I would shake your hand
因为我们欠你太多了
because we have
a lot to owe you.
我们还欠“机会科学”
We also owe
the science of chance
因为我们幸运地遇到了
because we lucked out
百万分之一的撞击
with a one
in a million impact.
如果忒伊亚撞击的强度再大一点
If the impact from Theia
had been a little bit harder,
地球可能就不会恢复得这么好
the earth may not have
recovered as well as it did,
我们也就不会在这里讨论这个问题了
and we may not be here
to talk about it right now.
但如果它没有那么强烈
If it had been a little bit
less forceful,
那么它的影响可能不会给我们带来
then the impact of it may no
have made the changes
我们现在认为需要的改变
that we think were needed
for us to be here now.
我们很幸运
We got lucky.
大多数行星不会在这样的碰撞中
Most planets
don't get to survive
a collision like that
幸存下来，并从中获得额外的卫星
and get a bonus moon
out of the deal.
地球与忒伊亚的巨大碰撞
Earth's
huge collision with Theia
并不是我们的星球第一次遭遇的危险
was not our planet's
first brush with danger.
在早期地球的形成的时期
An earlier explosive event
一次爆♥炸♥事件
could have stopped
the solar system
可能会阻止太阳系
from sparking into life...
产生生命……
...and the earth from formin
超新星是宇宙中最具破坏性的事情之一……
Supernovas
are one of the universe's
most destructive events...
其在一秒内所释放的能量
...releasing, in one second.
相当于太阳在整个一生中
...as much energy
as our sun will
所释放的能量
in its entire lifetime.
但超新星并没有毁灭我们
But rather than wipe us out
而是在46亿年前
supernovas may have
kick-started the solar syste
启动了太阳系
4.6 billion years ago,
那时的太阳系甚至不是真正的太阳系
the solar system's not even
really the solar system.