宇宙时空之旅（2014）

Cosmos: A SpaceTime Odyssey S01E11

Part 3 April 25, 2021, 12:41 p.m.

that it would take billions of years
要花费数十亿年的时间
for a rock ejected from the Earth
才能和另一颗恒星的行星♥相♥撞
to collide with a planet circling another star.
在如此长时间的宇宙辐射下
Any stowaway microbes would never survive
隐匿在岩石上的细菌根本无法存活
the cosmic radiation for that long.
但还是存在一套可能的理论
But there's a plausible scenario
证明生命能在不同的恒星系统间传播
for how life could spread from one solar system to another.
数千万颗恒星在引力作用下
The stars of the Milky Way are drawn by gravity
沿巨大的轨道绕银河系中心旋转
in their own enormous orbits around its center.
例如太阳
Our Sun, for example,
公转一圈
takes some 225 million years
要两亿两千五百万年
to complete a single orbit.
太阳系每绕银河转一圈
During each revolution around the galaxy,
就会穿过两到三个
our solar system will pass through two or three
巨大的星云
gigantic interstellar clouds,
每个星云都跨越了数光年
each of them many light years across.
银河系就是创世机器
Galaxies are world-making machines.
我们的银河系里有一百多个这样的巨大星云
Our Milky Way has more than 100 of these vast clouds,
气体和尘埃在这里集聚
a place where gas and dust condense
形成新的恒星和行星
to form new stars and planets.
在穿越银河系的旅程中
In its travels through the Milky Way,
太阳不仅被自己的行星环绕
our Sun is accompanied not only by its planets,
同时还有一万亿彗星远远相随
but also by a trillion distant comets.
当太阳系穿过一片星云时
When our solar system passes through an interstellar cloud,
大质量星云所产生的引力
the gravity of the massive cloud
会激发最外层的彗星
stirs up the outermost comets.
有些彗星会被抛出太阳系
Some comets will be hurled out
飞向恒星际空间
into the space between the stars.
另外一些则被推到太阳系内部
Others will plunge inward...
朝着太阳而来
falling towards the Sun.
其中的一些会和太阳的行星♥相♥撞
And some of them may collide with the planets.
岩态行星和彗星的高速碰撞
The high-speed impact of a comet with a rocky planet
会将许多岩石像火箭般射入太空
will launch boulders like rockets into space.
如果这颗行星上恰巧有生命存在的话
If that planet should happen to be inhabited,
很多岩石会携带乘客
many of those rocks will carry passengers--
有生命力的细菌
living microbes.
数千年后
After thousands of years,
从地球上抛出的岩石碎片
fragments of the rocks ejected from Earth
会以流星的形态进入那些在星云中
can fall as meteors into the atmospheres of newborn planets
新生行星的大气层
in the interstellar cloud.
如果流星中携带的细菌
If the stowaway microbes
能有幸接触到液态水的话
should happen to come in contact with liquid water,
它们就可以复苏并继续繁殖
they can revive and reproduce.
在毫无生机的行星里
This may be how life comes barreling
生命可能就是出现的
into the barren places.
从星云中诞生的恒星
The sun emerges from the cloud,
把生命的种子
having scattered the seeds of life
传播到其他新生恒星中
among the newborn worlds of other stars.
然后这些被赋予了生命的行星
Those new worlds, now touched by life,
将会离开孕育它们的母星云
will then leave their birth cloud
踏上自己的道路
and go their separate ways.
最终它们将在自己的恒星引领下
Eventually, their stars will carry them
穿越其他星云
through other interstellar clouds,
在那里它们可以继续传播种子
where they may seed still more new worlds.
想象一下这个过程在不同世界中反复发生
Imagine this process repeated from world to world,
每个世界都把生命带到其他地方
each one bringing life to others.
生命不断传播
Life would then propagate,
如同一个缓慢的连锁反应
like a slow chain reaction,
蔓延到整个宇宙
through the entire galaxy.
地球上的生命可能就是这么产生的
This could be how life came to Earth.
但我们也不太确定
We do not know for sure.
宇宙中有我们的同类吗
Are there any beings out there like us?
他们也在问这个问题吗
Do they ask the same questions?
他们和我们一样担忧吗
Do they share our fears?
他们那里也有英雄和冒险故事吗
Do they have heroes and adventures?
如果他们存在的话那他们在哪
If they do exist, where are they?
他们如何告知外界自己的存在
How might they make their presence known?
我们自己当初又是如何做到这一点的
How did we first announce our presence to the Galaxy?
1946年
It was 1946,
二战结束后的第一年
the year after the Second World War ended.
美军实现和月球的雷达通讯
纵是所拥有超凡想象力的
The vivid imaginations
赫伯特·乔治·威尔斯和巴克·罗杰斯
of HG Wells and Buck Rogers
也未曾想出
never cooked up a more
比新泽西州贝尔玛尔实验室的美军工程师
fantastic experience than the Army engineers at their laboratory
更为奇妙的构想
in Belmar, New Jersey.
这为空间实验
It opens up unlimited possibilities
创造了无限的可能
for interstellar experiment.
美国工程师们
American engineers
向月球发送了一段无线电波
bounced a beam of radio waves off the Moon,
并成功地接收到它的回声
and were able to detect its echo.
他们称这个实验为戴安娜计划
They called this experiment Project Diana.
这是人类发出的第一条
It was the first interstellar message
星际空间信息
ever sent by our species...
一段诡异的钟声
an eerie, tolling bell.
如果人类的想象力可以摆脱束缚
If one allows the imagination free reign,
未来就会出现无数可能
many future possibilities appear.
载人宇宙飞船
Spaceships, carrying passengers
时速达到几千千米
at thousands of miles per hour,
飞船上的乘客
can be controlled
可以操作飞船
and communication established
并和地球通讯
with their passengers,
因为我们现在已经知道通讯信♥号♥♥
for we now know that the Earth's atmosphere
是可以穿过大气的
can be penetrated.
无线电波以光速传播
Traveling at the speed of light,
只需一秒多的时间
it takes just over one second
就可以到达月球表面
for a radio wave to reach the lunar surface.
但不断扩大的波面远远大于月球
But the expanding wavefront is much bigger than the Moon.
所以多数无线电波都未能抵达月球
Most of the wave passes right by it,
但波的中心部分被月球反射
but the central part gets bounced back.
历经两秒半的往返时间
After a round-trip travel time of two and a half seconds,
无线电波回到地球
it hits our planet.
戴安娜计划通过发送
Project Diana transmitted
一连串每四秒一次的
a series of powerful radio waves--
高♥强♥度无线电波
one every four seconds--
来呼叫月球
to "Ping" The Moon.
没有抵达到月球的无线电波将继续传播
The parts that missed the Moon are traveling still.
这不过是序幕而已
It was just the beginning.
二战以后
After World War II,
电视台突然遍布全美
television stations cropped up all over the United States,
以及世界各地
and other parts of the world.
二十世纪以来的
The Project Diana message
戴安娜计划的无线电波
and the FM radio, television and
调频广播电视和雷达信♥号♥♥
radar signals of the 20th century
都是以光速来传播
all move outward at the speed of light.
传播产生了的巨大的球形无线电波
These transmissions make up a vast sphere of radio waves,
以地球为中心向四面八方扩张
expanding away from the Earth in all directions.
可以说我们的地球是在
You could say that our world
传播它的故事
is radiating stories.
我们的祖先把吉尔伽美什的故事
Our ancestors etched the story of Gilgamesh
刻入泥板
into clay tablets,
让那史诗般的故事流传到未来
sending that epic tale into the future.
我们则把我们的故事用无线电编码
We've encoded our stories in radio waves
然后发射到太空中
and beamed them into space.
自从无线电被发射出去起
They cover one light-year of distance--
每年它们都传播到一光年的距离
that's six trillion miles--
相当于9.5万亿千米
for every year of time since they were sent.
人类发射无线电♥信♥♥号♥♥到太空中去
We've been sending our stories into space
已经七十多年头了
for over 70 years.
最早发出的无线电♥信♥♥号♥♥
The leading edge of these signals
早已掠过数千颗其他恒星的行星
has already washed over thousands of planets of other stars.