了解宇宙是如何运行的（2010）

How the Universe Works S05E07

Part 6 April 18, 2021, 7:47 p.m.

所以我们有保护
So we have an ethical responsibility
火星上任何生命的道德责任
to preserve whatever life may be on Mars.
问题并不在于我们
The problem isn't us,
而在于我们体内和体内的细菌
it's the bugs in and on our bodies.
平均有10到20万亿细菌
The average human has
正在搭乘我们人类身体的便车
ten to 20 trillion bacterial hitchhikers.
如果我们去火星
If we go to Mars,
我们就会带上我们的“小同伴”
we'll be taking our tiny companions along for the ride,
而这些“小虫子”中的任何一个都有可能
and any one of those bugs could turn out to be
成为火星生命的致命竞争对手
a deadly competitor for martian life.
NASA工程师穆格加·库珀的工作
It's NASA engineer moogega Cooper's
就是确保火星漫游者没有“虫子”
job to keep Mars rovers bug-free.
但是要让宇航员保持“清洁”那就是另一回事了
But keeping astronauts clean, that's a whole different matter.
如果为了防止火星污染
We bake our spacecraft hardware
我们要把设备在110摄氏度的温度下
at 110 degrees celsius for at least 50 hours
炙烤至少50个小时
to prevent the contamination of Mars.
但与宇宙飞船不同的是，我们不能烧烤人类
But unlike spacecraft, we cannot bake humans out.
我们无法在这样的温度下生存
We will not survive those temperatures.
除非我们找到一种方法
Unless we find a way
让宇航员远离“虫子”
to keep astronauts bug-free,
否则利用机器人去探索火星
exploring Mars with robots is our best option
是我们保护火星生命免受伤害的最佳选择
for keeping the martians safe from harm.
但是，当我们的机器人
But what will happen when our robots
最终发现生命，而我们要深入研究我们的外星邻居时
finally find that life and we look deep into the workings
会发生什么情况呢？
of our extraterrestrial neighbors?
火星生命会变成什么样呢？
What will the martians turn out to be like?
比如我们地球生命，DNA是
Our example where DNA is the organic molecule
携带生命信息的有机分子……
that carries the information of life ...
我们都不知道
we don't even know
这样方式在其他地方会不会成为惯例
if that's gonna be the rulebook in other places.
在火星上找到任何证据
Finding any evidence whatsoever on Mars
都能帮助我们更好地了解其他可能的情况
would help us better understand what else is possible.
火星生命
Will the martians
会和我们不同吗？
be different than us?
是否是由不同的材料
Made from different materials
和不同的生物化学组成？
and with a different biochemistry?
还是说它们看起来非常熟悉？
Or will they seem shockingly familiar?
一些科学家认为最早的火星生命
Some scientists think that the very first martian life
可能并没有留在火星上
may not have stayed on Mars.
它可能已经来到了这里
It may have come here.
有一种理论认为生命可能源自火星
It's not that farfetched to think
或者在火星和地球之间来回穿梭
that life could have jumped from Mars
这并不是牵强附会
or been a back and forth from Mars to earth.
如果火星生命来到地球
If the martians came to earth,
他们会在我们的星球上播种生命的种子吗？
could they have seeded life on our planet?
也许火星生命并没有死
Maybe the martians aren't dead.
也许我就是火星人，也许你也是火星人
Maybe I'm a martian, maybe you're a martian.
我们已经向火星派出了一支机器人军队
We've sent a robot army to Mars,
它的发现令人震惊
and what it's found is astonishing.
生命可能在那里出现过
The possibility that life could have arisen there,
也许不止一次
perhaps more than once,
不同世代的火星生命在灾难性的灭绝事件后
with different generations of martians emerging from the ashes
从灰烬中诞生
of catastrophic extinction events.
现在火星表面下
Life could still be sheltering
可能还隐藏着生命
below the surface of Mars right now.
但还有另一种真正能令人震惊的可能性……
But there's another possibility that's truly astounding ...
火星生命不只是躲在火星上
that martians aren't just hiding out on Mars,
他们已经在地球上茁壮成长
they're thriving, right here on earth.
我可能是火星人
I might be a martian,
你也可能是火星人
you might be a martian.
我们可能来自另一个星球
We might be from another planet.
我们可能已经作为生命的形式在两个星球上
We might have already travelled and lived on two planets
旅行和生活了……当然，不是作为一个物种
as life forms ... not as a species, certainly,
我们的祖先可能来自另一个星球
but our ancestors may have come from another planet,
这真的令人震惊
and that is mind blowing.
我们的祖先
The idea that our ancestors
可能源自火星生命的理论
could be martians is a new take on an old theory
被称为生源说
called panspermia.
根据该理论
According to the theory,
地球上的生命始于一块
life on earth began when a space rock
充满外星细菌的太空岩石降落在地球上
filled with alien bacteria landed on the earth
我们今天看到的所有生物，包括我们自己
and every living thing we see today, including us,
都是从那些宇宙漫游者进化而来的
evolved from those cosmic hitchhikers.
生源说的概念已经存在了几个世纪
The idea of panspermia has been around for centuries,
但当科学家们确定
but had a resurgence when scientists
地球上的生命可以追溯到40亿年前
determined that life on earth may go back four billion years,
即被称为晚期重轰炸的小行星雨持续攻击的末期时
to the end of a sustained attack of asteroid showers
生源说又重新流行起来
known as the late heavy bombardment.
有很多来自太阳系外的物体……
There are a lot of objects from the outer solar system ...
彗星，小行星，和各种各样的东西……
comets and asteroids, all kinds of things ...
进入太阳系内部
coming into the inner solar system
并撞击行星
and slamming into the planets.
传统观点认为
Conventional wisdom
当时撞击地球的物体
suggests the objects hitting the earth at the time
是太阳系形成时
were leftover debris
遗留下来的碎片
from the formation of the solar system.
但有一种非常有争议的观点认为
But a very controversial idea
这些太空岩石实际上都是火星的碎片
suggests these space rocks were actually all pieces of Mars,
是一个巨大的物体撞击火星时
thrown off in the borealis space impact
即北极撞击的太空撞击中抛下的
when a huge object blasted into Mars.
对于北极撞击的太空撞击来说，时间上的联♥系♥真的很好
The timing links up really well for the borealis space impact.
如果你根据火星地质记录
If you calculate how much debris
计算一下有多少碎片
that would have been thrown out into space
会被抛到太空中以及可能
and when it would have had to have happened,
在什么时候发生，你会发现
according to the martian geologic record,
这与后来的猛烈撞击是一致的……
it coincides with the late heavy bombardment...
有可能来自北极撞击的碎片
It's possible that the debris
在形成撞击的过程中
from the borealis space in forming impact
来到了地球，并像雨点一样落在我们身上
might have come to earth and rained down on us
形成了后期的重轰炸
and made the late heavy bombardment,
在地球上播撒了火星的细菌孢子
seeding the earth with bacterial spores from Mars.
现在，这只是一个假设，我们还不确定
Now, this is just a hypothesis, we don't know this for certain,
我们没有证据
we don't have evidence.
但这在物理上是有可能发生的
But it is physically possible for that to have happened.
地球的种子
Was the earth seeded
是由微小的火星生命
by microscopic martians
在北极撞击的影响下被吹到太空中的吗？
blown into space by the borealis impact?
这听起来很疯狂，但科学证明是可以的
It sounds crazy, but the science stacks up.
我们知道简单的生命是很顽强的
We know that simple life is tough,
它们能够在太空的寒冷真空中生存
able to survive in the cold vacuum of space,
而北极撞击的时间
and the timing of the borealis impact
正好是地球上第一个生物出现的时间
works out well for the rise of the first organisms on earth.
最重要的是，我们知道从火星喷射出来的岩石
Crucially, we know that rocks ejected from Mars
能够一路到达地球
can make it all the way to earth
因为即使在今天，它们仍然会在这里紧急着陆
because they're still crash landing here, even today.
作为一名科学家，我做过的最酷的事情之一
One of the coolest things I've done as a scientist
就是把一块火星石拿在手里
is held a piece of Mars in my hands.
现在，我们从未有过从火星返回样本的任务
Now, we never had a mission that returned a sample from Mars,
我们必须采取另一种方式
we had to come about it a different way.
事实证明，我们有一些陨石
And it turns out we have meteorites
我们100%确定是火星的碎片
that we are 100% sure are bits of Mars.
它们实际上是在巨大的碰撞中爆♥炸♥
They were actually exploded out during huge collisions,
并最终降落到地球上
and eventually they fell on the earth.
四代不同的火星生命
Four different generations
都面临着不同的
of martians, each of them facing
星球灾难
a different planetary catastrophe.
尽管被毁灭的可能性很大
But despite enormous odds,
然而火星生命今天仍然有可能活着
martians could still be alive today,
深埋在火星地表之下
buried deep under the surface of Mars,
甚至可能在地球上繁衍生息
or maybe even thriving on earth.