了解宇宙是如何运行的（2010）

How the Universe Works S05E07

Part 2 April 18, 2021, 7:47 p.m.

如果与6500万年前
You're talking about an impact
使恐龙灭亡的那次撞击比起来
that makes the dinosaur killer impact
那次撞击就显得非常微不足道了
65 million years ago look pretty much like a wet firecracker.
45亿年前
4.5 billion years ago,
早期的太阳系
the early solar system is filled
充满了星子和原行星……
with planetesimals and protoplanets ...
即火星和地球形成的过程中
asteroid-like leftovers from a planet building process
留下的类似小行星的残留物
that created Mars and the earth.
其中一颗小行星非常巨大
One of these asteroids is huge,
它与火星发生了直接碰撞
and it's on a direct collision course with Mars.
任何微小的火星生命都面临灭顶之灾
Any microscopic martians have just seconds to live.
如果这次撞击发生在今天
If this impact was happening today
而我们很不幸地目睹了这次事件
and we were so unlucky as to be there to witness it,
你首先看到的将是天空中出现了另一个月亮……
what you first would have seen is another moon in the sky...
然后当你再看到它时会发现
And then you would've looked back and seen,
哦，它越来越大了
oh, it's getting bigger.
当它落下来时，它会布满整个天空
As it came down it would have filled the entire sky,
从地平线到地平线
from horizon to horizon,
而当它撞击的时候
and as it struck,
它的顶部仍然远在太空中
the top would have still been well out into space.
撞击者
The impactor
直径1200英里
is 1200 miles across,
相当于冥王星的大小
the size of pluto,
当撞击时，撞击产生的能量
and as it hits, the energy of the impact
会使整个火星震撼
shakes Mars to its core.
整个星球就像果冻一样摇摆不定
The entire planet wobbles like jell-o.
当它落下时
As it came down,
它会以枪里射出的子弹一样快的速度
it would have been hitting into the surface of Mars
撞击火星表面
as fast as a bullet out of a gun,
碰撞的一刹那产生的冲击波
and it would have slammed into the surface
所释放出的能量
and sent a shockwave out
比任何有记录的地震都要大
that would've been bigger than any earthquake ever recorded.
就像一场岩石海啸冲出来
It would have been like a Tsunami of rock
把我们甩到一边
coming out and tossing us out of the way.
这个影响是灾难性的
The impact is catastrophic.
它将星球近一半的表面吹入太空
It blows nearly half the planet's surface into space
将残留的地壳变成沸腾的熔岩湖
and turns what crust remains into a boiling lake of lava.
你无法想像整个星球融化
You can't have an impact of that scale
所产生影响的规模有多大
without almost melting the planet.
这并不是一个真正意义上的行星破碎事件
It's not literally a planet breaking event,
而是一个行星融化事件
but it's a planet melting event,
确实是这样，在这个事件点上
and it is, it is the sterilization
星球被毁灭了
of the planet at that point.
火星的表面是熔化的
The surface of Mars was molten,
它的大气层被吹到太空中
its atmosphere blown into space,
海洋也被蒸发了
the oceans boiled away.
如果火星是我们太阳系中
If Mars was home to the first generation of life
第一个生命的家园
in our solar system,
那现在它可能已经不存在了
that life didn't stand a chance.
火星表面需要5000万年
It would take the surface of Mars 50 million years
才能从撞击中恢复过来
to recover from the impact.
但什么样的星球会从灰烬中重生呢？
But what sort of planet will rise from the ashes?
令人信服的新证据表明，火星可能已经
Compelling new evidence suggests that the conditions for life
恢复了生命的生存条件
may have returned to Mars,
但生命本身是否又重新出现了呢？
but did life itself make a comeback?
这次撞击只是时间上的一个小插曲
This impact was only a blip in time,
生命和星球
and there was possibilities for life
都有可能会恢复
and the planet to recover.
45亿年前
4.5 billion years ago
一颗冥王星大小的小行星
an asteroid the size of pluto
撞击了初生的火星表面
slammed into the surface of infant Mars.
它融化了行星的表面
It melted the surface of the planet,
将大气层吹入太空
it blew the atmosphere into space,
海洋也蒸发了
and it boiled away the oceans.
如果生命在这颗行星上有了立足之地
If life had gotten a foothold on the planet,
那它们早就完全灭绝了
that life would have been completely exterminated.
但一些科学家认为，这次灭绝
But some scientists believe this extinction
可能是短暂的
could have been brief,
生命可能会从零开始
and that life could have started again from scratch.
可以想象
One of the wonderful things
一件美妙的事情是，生命的起源
to imagine is that there probably wasn't
可能不是单一的
a single origin of life.
并不是发生过一次后
It's not like it happened once
然后一切就都结束了
and then everything just went from there.
也许有很多次生命开始
Maybe there were multiple times that life got started
然后灭绝
and went extinct.
在那次
Ten million years
撞击火星北半球的
after the borealis impact
“北极撞击”事件的1000万年之后
crushed the planet's northern hemisphere,
火星的温度已经冷却到
Mars has cooled enough for its surface
足以使其表面再次变成固体
to become solid once more.
这颗行星已经有了生命的一些成分……
The planet has some of the ingredients for life ...
有生命的分子，稳定的表面
the right molecules, a stable surface,
以及能量来源
and an energy source.
但还是缺一样关键要素
But something's missing.
44.9亿年前的火星，地表面是干燥的
4.49 billion years ago the surface of Mars was dry,
没有水，生命无法重新开始
and without water, life can't start over
第二代火星生命永远不会出现
and a second generation of martian can never arise.
据我们所知
As far as we know life,
水对生命来说绝对是至关重要的
water is absolutely, fundamentally important to life.
2004年……美国宇航局的机遇号♥探测器
2004 ... NASA's opportunity rover
登陆火星
lands on Mars.
它的任务之一是寻找
Part of its mission is to search for evidence
北极撞击火星后水返回火星的证据
that water returned to Mars after the borealis impact.
没过多久
It's not long before opportunity
“机遇号♥”在一个沙丘化石表面偶然发现了
stumbles across something strange on the surface
一些奇怪的东西……
of a fossilized sand dune...
奇异的、圆形的金属岩石
Bizarre, round, metallic rocks.
这些岩石被称为蓝莓石
These rocks are called blueberries,
对贾尼·拉德博(jani radebaugh)这样的行星地质学家来说
and they're an important find for planetary geologists,
它们是一个重要的发现
like jani radebaugh,
因为地球上也存在石化沙丘地貌
because fossilized sand dunes also exist on earth.
犹他州的石化沙丘上
And Utah's petrified dunes
也散落着蓝莓石
are also littered with blueberries.
这真的很令人兴奋
This is really exciting
因为我们在火星上也看到了同样的情况
because we've seen the exact same thing on Mars.
在火星上发现蓝莓石
Finding blueberries on Mars
意义重大，因为北极撞击
is significant, because the borealis impact
融化了火星
melted the planet,
所以今天在火星上发现的任何东西
so anything found on Mars today
都一定是在那次撞击后形成的
must have formed after the impact.
但至关重要的是，这些氧化铁结核
But crucially, these nodules of iron oxide
是在地下深处形成的而且是在有水的情况下形成的
formed deep underground and in the presence of water.
为了形成这样的一个小蓝莓石
In order to form one of these little blueberries,
需要大量水的
there needs to be huge amounts of water
从石化沙丘中冲下来
flushing down through the fossil sand dunes,
在此过程中
and as it does that,
每一粒沙粒周围
it carries with it all of the iron oxides
都带着铁的氧化物
around each sand grain.
就像这样很小很小的一个…
And just one tiny, little one like this ...
现在，这可能是
now, this is maybe about
大约一盎司的铁，可能更多一点……
an ounce of iron, maybe a little bit more ...
为了得到浓缩了
and in order to get an ounce of iron
一盎司铁的蓝莓石
to concentrate into this blueberry,
你需要一千加仑的水
you need to have a thousand gallons of water.
蓝莓石形成于
Blueberries form
砂岩深处
deep inside sandstone.
但几千年来
But over thousands of years,
风蚀将较软的岩石吹走
wind erosion blows away the softer rock,
最后只留下蓝莓石
leaving just the blueberries behind.