宇宙时空之旅（2014）

Cosmos: A SpaceTime Odyssey S01E13

Part 4 April 25, 2021, 12:41 p.m.

其密度为地球大气的四倍
four times denser than Earth's.
这意味着土卫六上可能存在碳氢海洋
That hinted at the existence of hydrocarbon seas on Titan,
这一推测后来被证实
which we later confirmed.
旅行者二号♥为我们绘制了
Voyager 2 gave us our first portrait
最外层行星海王星的第一幅图像
of the outermost planet, Neptune...
那里的狂风以每小时
where the winds roar
2000多千米的速度咆哮着
at 1,000 miles per hour...
而海卫一上有着将沸腾的液氮
and its moon Triton, where geysers
喷射到八千多米高空的间歇泉
of boiling nitrogen shoot five miles high.
旅行者号♥已经成功完成了
Voyager successfully completed its mission of discovery
对外层行星的探测任务
to the outer planets,
然而它驶向黑暗的旅程
but its odyssey into the darkness
才刚刚开始
was just beginning.
在发射三十五年之后
35 years after its launch,
旅行者一号♥成为人类历史上第一艘
Voyager 1 became the first of our spacecraft
驶入尚未测绘宙域的航♥天♥器
to enter an uncharted realm.
太阳不断地向各个方向喷射出
The Sun is constantly shooting out streams
每小时移♥动♥数百万千米的
of charged particles in all directions,
高速带电粒子流
moving at a million miles an hour.
太阳风吹起一个巨大的磁泡
This solar wind blows a vast magnetic bubble,
那就是我们的日球层
our heliosphere,
它一直延伸到外层行星之外
that extends beyond the outer planets.
日球层把星际间的稀薄气体向外推
It pushes out against the thin gas of interstellar space.
那是太阳系边缘和星际海洋起始的分界线
There's a border where one ends and the other begins.
旅行者一号♥向地球传回报告
Voyager 1 reported back to Earth
显示其探测装置被
that its detectors were being pummeled
越来越多的宇宙线击中
by more and more cosmic rays.
直到那时
Until then,
我们才知道此处便是星际海洋的开始
we didn't know where the interstellar ocean began.
旅行者一号♥继续前进
Voyager 1 pressed on
跨过我们此前从未涉足的边界
past a boundary we had never crossed before.
日球层为我们屏蔽了大部分致命的宇宙线
The heliosphere shields us from most of the deadly cosmic rays.
当太阳风暴暴发时
When stormy solar winds blow,
日球层提供的保护区变大
this zone of protection grows;
当太阳风风平浪静时保护区缩小
In calm solar weather, it shrinks.
当我们星系中某个临近的恒星超新星爆发时
When a star goes supernova in our galactic neighborhood...
恒星爆♥炸♥后的碎片
the debris from the exploded star
将日球层向太阳的方向推
pushes the heliosphere back towards the Sun.
如果爆发足够强
If it's strong enough to push it
甚至能将日球层推回到地球轨道
all the way back to Earth's orbit,
我们的星球就将接受
our planet gets
超新星爆发后的放射碎片洗礼
a radioactive bath of supernova debris.
幸运的是这并不经常发生
Luckily, this doesn't happen very often.
上一次大概是在两百万年以前
The last one was perhaps two million years ago.
一颗邻近的恒星在
A neighboring star explodes a million years
人类出现前的一百万年爆发
before there's even such a thing as the human species.
我们怎么知道这件事的呢
How can we possibly know this?
因为这颗濒死的恒星
Because the dying star left its traces
将它的遗迹留在了几千米深的海底
miles below the surface of the ocean.
锰结核像这样的小岩石块
Manganese nodules, small rocks like this one,
广泛分布在海洋底层的深处
are scattered over much of the deep sea floor.
它们生长得非常缓慢
They grow very slowly.
一百万年才长一毫米
I'm talking a millimeter in a million years,
一层叠一层地生长
layer upon layer.
这些凝团和细菌合作
These nodules grow in partnership with bacteria
通过汲取溶解在海水中的矿物质生长
by taking up minerals dissolved in the seawater.
超新星爆发生成了铁的一种放射性同位素
A supernova produces a radioactive form of iron,
它跟地球上任何自然过程的产物迥然不同
unlike anything made by natural processes on Earth.
研究人员在这些锰结核
Researchers found telltale traces of this iron
表面之下的薄层中
in a thin layer below the surface
发现了这种同位素
of the manganese nodules.
他们利用这种凝团已知的生长速率
They used the known rate of growth of the nodules
来确定该薄层的年代并将其和
to date that layer and to connect it
百万年前消殒的一颗恒星的命运联♥系♥起来
to the fate of a star that perished eons ago.
从只看到一枚卵石
The difference between seeing nothing but a pebble
到读出镌刻其上的宇宙历史
and reading the history of the cosmos inscribed inside it
其间的桥梁正是科学
is science.
星际海洋黑暗而深邃
The interstellar ocean is dark and deep.
从那里来看
Out here,
太阳不过是天空中最亮的一颗星星
the Sun is just the brightest star in the sky.
然而旅行者号♥保持着它们
Yet the Voyagers maintain their regular communications
与美国宇航局喷气推进实验室的常规通信
with NASA's Jet Propulsion Laboratory,
这些飞船和相隔数十亿千米的
talking back and forth across the light-hours
母港交换着信息
that separate these ships from their home port.
没有任何其他带有人类印记的东西
No other objects touched by human hands
曾来到如此远离地球的地方
have ever ventured this far from home.
即使在它们无法再回应我们的命令之后
Even after they lose their ability to respond to our command,
旅行者号♥任务的最后一个阶段
the last and, by far, the longest phase
也是目前为止最长的一个阶段即将开始
of the Voyager mission will begin.
1979年两艘旅行者号♥在绕行木星时
Back in 1979, when both Voyagers rounded Jupiter,
其巨大引力产生的弹弓效应
its massive gravity acted as a slingshot,
将它们抛出太阳系
flinging them out of the Solar System
使其能在银河系的恒星之间
to travel among the stars of our galaxy
航行十亿年
for a billion years.
卡尔·萨根意识到旅行者号♥任务
Carl Sagan recognized that the Voyager mission
提供了两张通向某种永恒的免费门票
offered two free tickets to something approaching eternity.
他组织了一个小团队来构思一条讯息
He assembled a small team to create a message
用来传达给可能在某天邂逅这些
to any civilization that might, one day,
被弃置的航♥天♥器的任何智慧生命
encounter the derelict spacecraft.
二十六个世纪前
26 centuries ago,
亚述国王以撒哈顿曾写道...
the Assyrian King Esarhaddon wrote...
"我有青铜制成的纪念碑
"I had monuments made of bronze
和黏土烧制的铭文
and inscriptions of baked clay.
以其奠基必可流传后世"
I left them in the foundations for future times."
这里的象形文字延续了这一古老的理念
These hieroglyphics continue that ancient tradition.
镌刻在这里的讯息是专门设计以供
They are inscribed on the cover of a message designed
另一个世界另一个时代的生命阅读
to be read by the beings of other worlds and times.
地球文明和外星文明
What could we possibly have in common
会有哪些可能的共同点呢
with an alien civilization
特别是那些具有独♥立♥进化史的
with its own separate evolutionary history
远远领先于地球文明的
and one so far advanced beyond us
以至于能够在星际空间巡逻的外星文明
that they can patrol interstellar space?
至少有一点
One thing at least,
一门通用的语言
a universal language...
科学
science.
摆脱引力的束缚是困难的
It's hard to break the bonds of gravity.
要航行于宇宙之海
You can only sail the cosmic seas
你必须精通数学和物理
if you speak mathematics and physics.
氢是宇宙中最普遍的元素
Hydrogen is the most common element in the universe.
氢原子中的电子
The electron in a hydrogen atom
以固定的频率
flips the direction of its spin
反转其自旋的方向
at a constant rate, or frequency.
氢原子就像微小的自然时钟
Hydrogen atoms are like tiny natural clocks--
嘀嗒
Tick... tock...
这样我们就和外星人
Now we have a unit of time in common
有了相同的时间单位
with the extraterrestrials.
这在理解我们的下一条讯息时
This will come in handy when we get to
是很有用的
the next level of the message.
这就是我们在宇宙中的回信地址
Here's our return address in space.
脉冲星是高速旋转的中子星
Pulsars are rapidly-spinning neutron stars
它们发出规则的无线电波脉冲
that give off regular bursts of radio waves.
可以用它们来校准时钟
You can set your clock by them.
太阳位于这张图像的中心
The Sun is at the center of this diagram,
而那些射线指向离它最近的十四颗脉冲星
and the lines point to the 14 nearest pulsars.
一组简单的代码标注了
A simple code labels each pulsar
每颗脉冲星特有的频率
with its unique frequency,
采用的正是氢原子钟
using the ticktock of the hydrogen atom
这样的计时单位
as the unit of time.
因此外星天文学家可以利用这幅地图
So alien astronomers could use this diagram
来定位银河系中的
to locate the home star of the