宇宙时空之旅：未知世界（2020）

Cosmos: Possible Worlds S01E03

Part 2 Aug. 24, 2022, 10:55 a.m.

宇宙年的3月15日
March 15 of the cosmic year,
我们的银河系开始形成
when our Milky Way galaxy began to form.
“八月”
又过了60亿年
Six billion years after that
我们的恒星也就是太阳诞生了
our star, the Sun, was born.
那天是宇宙日历的8月31日
It was August 31st on the Cosmic Calendar.
木星和其他行星
Jupiter and the other planets
包括我们的地球
including our own
很快会跟着出现
would soon follow.
这是将近40亿年前的地球
This was our planet nearly four billion years ago...
宇宙日历的9月21日
September 21st on the Cosmic Calendar,
我们相信生命在这时出现
when we believe life began.
大气层全是碳氢化合物的烟雾
The atmosphere was a hydrocarbon smog.
没有氧气可吸
No oxygen to breathe
也没有生物吸收氧气
and no one to breathe it.
我们最近才开始明白
We've only recently begun to appreciate
生命如何主宰了地球的形成
how powerfully life has shaped the planet.
想到生命如何改变地球
When we think about the ways life has changed Earth,
首先想到的是绿色的广袤森林
the first things that come to mind are the green expanses of forests
还有恣意蔓延的城市
and the sprawling cities.
但生命开始改变地球时
But life began transforming the planet
森林和城市连个影子都没有
long before there were any such things.
在海底冒出那少许微光的十亿年后
A billion years after that tiny glimmer at the bottom of the sea,
生命成了全球性的景象
life had become a global phenomenon
全靠一位迄今战无不胜的斗士
thanks to a champion that to this day has never been vanquished.
向各位介绍蓝细菌
I give you the cyanobacteria.
27亿年前出道江湖
In business for 2.7 billion years,
蓝细菌在哪里都混得下去
cyanobacteria can make a living anywhere.
淡水盐水温泉盐矿.
Fresh water, salt water, hot springs, salt mines...
毫无区别
makes no difference
蓝细菌都能怡然自得
it's all home to them.
“十二月”
在接下来的4亿年里
Over the next 400 million years
蓝细菌吸入二氧化碳
the cyanobacteria... taking in carbon dioxide
呼出氧气
and giving back oxygen,
把天空变成蓝色
turned the sky blue.
但蓝细菌不仅改变了天空
But the cyanobacteria didn't just change the sky,
还深入岩石深处
they reached into the very rocks themselves
让顽石低头
and changed them, too.
氧气使铁生锈
Oxygen rusted the iron,
在矿物上施展魔力
working its magic on the minerals.
在地球上的5000种矿物中
Of the 5,000 kinds of minerals on Earth,
有3500种
3,500 of them
是生命创造的氧气的产物
arose as a result of the oxygen made by life.
不过拉清单的日子来了
But here comes that day of reckoning.
蓝细菌是当时主宰地球的生物
Cyanobacteria were the dominant life-form on this planet
所到之处无不哀鸿遍野
wreaking havoc wherever they went,
改变了地貌、水和天空
changing the landscape, the water and the skies.
这是23亿年前
This was 2.3 billion years ago,
也就是宇宙日历的十月底
or late October on the Cosmic Calendar.
不过地球上不只蓝细菌一种生物
But the cyanobacteria shared the planet with other beings:
还有比蓝细菌虚长几岁的生物厌氧菌
The anaerobes, life-forms that had come of age before
蓝细菌已经开始用氧气污染地球
cyanobacteria had begun to pollute the Earth with oxygen.
对厌氧菌而言
For the anaerobes
氧气就是毒药
oxygen was poison
但是蓝细菌不停地
but the cyanobacteria wouldn't stop
把氧气送进大气层
loading up the atmosphere with the stuff.
不管是厌氧菌
For the anaerobes
还是地球上几乎其他所有生物
and nearly all of the other life on Earth
都差点被氧气灭绝
it was an oxygen apocalypse.
幸免遇难的厌氧菌
The lone survivors among the anaerobes were those
只能孤零零的躲在海底
who sought refuge at the bottom of the sea,
在那些氧气无法到达的沉积物深处
deep in the sediment where the oxygen could not reach them.
蓝细菌就像氧气泵
The cyanobacteria acted like oxygen-pumping machines.
继续以超高速运转
They continued in overdrive
4亿年后
and 400 million years later
为地球带来更彻底的改变
they brought about an even more radical change to the planet.
还记得那些蛇纹岩
Remember those serpentinized rocks at the bottom of the sea
在海底产生氢气和甲烷吗
that were cranking out hydrogen and methane?
甲烷是一种强效的温室气体
Methane is a powerful greenhouse gas,
当时全靠甲烷为地球保温
and back then it was the main thing keeping the planet warm.
不过生命制♥造♥的氧气
But once again, the oxygen produced by life
再度带来巨变
shook things up.
它吞噬了甲烷
It gobbled up the methane
产生了二氧化碳
producing carbon dioxide,
这种温室气体的效果差多了
a much less potent greenhouse gas...
无法同样有效地
meaning it was not as efficient
保留大气层中的热量
at trapping heat in Earth's atmosphere.
地球的温度开始骤降
Earth's temperature began to plunge.
生命这个逃脱大♥师♥
Life, the escape artist
挣脱了把地球冰封的致命魔掌
busted out of the icy death grip that entombed the planet.
细菌死后留下的二氧化碳
The corpses of dead bacteria left
把地球团团包围
behind a planetwide reservoir of carbon dioxide.
火山将大量的二氧化碳
Volcanoes pumped the carbon dioxide
排放到大气层中
in huge quantities into the atmosphere
温暖了地球融化了冰
warming the planet and melting the ice.
在接下来的十亿年里
Over the next billion years,
生命和岩石继续相互配合
life and the rocks continued their elaborate dance,
使地球数次结冰和融化
taking the planet through freezes and thaws.
然后在5.4亿年前
Then, 540 million years ago
奇迹出现了
something wondrous happened.
生命原本只是微生物
Life, which had been all about microbes
和简单的多细胞生物
and simple multicellular creatures
突然一飞冲天
suddenly took off in what's
出现了所谓的寒武纪大爆发
called the Cambrian Explosion.
生命长出了腿、眼睛、鳃、牙齿
Life grew legs, eyes, gills, teeth,
并且很快开始演化出
and rapidly began to evolve
数不胜数的形式
the forms of its stunning diversity.
我们目前不知道是什么因素
We don't yet know what
让生命变得如此丰富多彩
it was that allowed life to diversify so dramatically
但我们有几个合理推测
but we have some plausible theories.
可能是海底那些火山
It could have been all those calcium minerals
喷出的钙矿物质
in the seawater that came from the volcanoes.
让生命长出了脊柱
Life had grown a backbone
穿上了外壳
and put on a shell.
成功和岩石合作
It had found a way to collaborate with the rocks
制♥作♥自己的盔甲
to make its own armor.
现在生命可以变得更大
Now life could grow larger
到新的领域探险了
and venture forth into new territories.
或者可能是蓝细菌制♥造♥的屏障
Or maybe it was the protection afforded by the canopy
提供了保护
built by the cyanobacteria.
大气的氧化作用产生了臭氧层
The oxygenation of the atmosphere created the ozone layer.
让生命得以突破安全的海洋
This made it possible for life to break out of
登上陆地栖息
the safety of the oceans and inhabit the land
免受太阳致命的紫外线攻击
without being assaulted by the sun's deadly ultraviolet rays.
数十亿年来
For billions of years
生命只能蜗行牛步
all life could do was ooze.
现在
Now
生命开始游泳
life began to swim
奔跑、跳跃和飞翔
run, jump and fly.
生命这个逃脱大♥师♥
Life, the escape artist
可以轻易挣脱任何桎梏
had gotten so good at wriggling out of every confine
地球的牢笼关也关不住
no prison on Earth could hold it.
迟早有一天
And there will come a day,
生命甚至可以逃离地球
when life would even escape from Earth.
想拦也拦不住
Life will not be contained.
要对生命的演化追本溯源
Retracing life's odyssey back to the very beginning
需要一种新的科学
required a new kind of science,
重新结合好几门学科
one that reunited the disciplines.
创立这种全新研究方法的人
The man who founded this new approach also happened
本身正好也是逃脱大♥师♥
to be an escape artist himself.