宇宙时空之旅（2014）

Cosmos: A SpaceTime Odyssey S01E04

Part 3 April 25, 2021, 12:39 p.m.

它对遥远的恒星一样有效
that it also rules the distant stars.
父亲但是您是怎么发现的呢
Father... but how can you know this?
你能不能找到狮子座
Can you find the constellation of the Lion?
在那里
There.
很好
Well done.
那你能不能找到
Can you now find the star
狮子脖子处的恒星
that joins the lion's head to his body?
是那个
That one.
那颗恒星其实是两颗恒星
That star is really two stars
它们彼此很近所以看起来像是一颗
so close together that they appear to be one.
我自你出生前很久就开始
I've been watching them through my telescope
用望远镜观察它们了
since long before you were born.
它们非常缓慢地围绕着彼此起舞
They dance around each other very slowly.
比一般行星公转的速度慢得多
More slowly than any planet moves around the Sun.
很多我们今晚看到的恒星
Many of the stars we see tonight,
也许是大多数
perhaps most of them,
都在与它们看不见的舞伴舞蹈
dance with invisible partners.
引力帝国统治着一切天上的世界
Gravity's empire governs all the heavens.
一个世纪前
A century earlier,
艾萨克·牛顿也因
Isaac Newton had been haunted
不了解产生引力的机制而困扰
by the same absence of a mechanism for gravity.
相隔甚远的天体
How could distant bodies affect each other
如何跨越真空不接触彼此而相互影响呢
across empty space without actually touching?
他所称的"远距离作用"使他困惑
This "action at a distance," as he called it, baffled him.
在19世纪迈克尔·法拉第发现了
In the 19th century, Michael Faraday discovered
我们正被不可见的力场包围
that we were surrounded by invisible fields of force
这解释了引力的原理
that explained how gravity works.
苹果和地球并没有直接接触
The apple and the Earth don't touch each other,
但是它们间的场却可以
but the fields between them do.
他想象这些引力线
He imagined those lines of gravitational force
从所有大质量天体向四周发射
radiating out into space from every massive body--
包括地球月球太阳所有物体
the Earth, the Moon, the Sun, everything.
把牛顿难住的问题
Here was the answer to that question
得到了答案
that had stumped Newton.
1865年詹姆斯·克拉克·麦克斯韦
In 1865, James Clerk Maxwell translated Faraday's idea
为法拉第关于电场和磁场的想法
about fields of electricity and magnetism
建立了数学方程
into mathematical laws.
他发现这些场以波的形式传递
He discovered that these fields move through space in waves.
当他计算它们能传多快时
When he calculated how fast they move,
竟发现它们的速度是光速
it turned out to be the speed of light.
我们发现了宇宙的壁毯上交织的线
We were beginning to discover the threads of the cosmic tapestry,
但是我们还没法领悟出上面丰富的图案
but we were not yet able to discern the rich pattern
如时间光空间引力的编织方法
that time, light, space and gravity weave.
当阿尔伯特·爱因斯坦在柏林
As Albert Einstein worked in Berlin
研究他的引力理论时
on his theory of gravity,
他将前三者的画像都放到了面前
he kept the portraits of these three men before him.
他知道自己是站在他们的肩膀上
He knew he was standing on their shoulders.
数年前还是青少年的他
Years before, as a teenager, he had an insight
就展现出和他们一样惊人的洞察力
that was as Earth-shaking as any idea of theirs.
一个夏天当他在意大利
And it happened one summer
做着白日梦时发生了
while he was daydreaming in Italy.
在1♥8♥9♥5年的夏天
In the summer of 1♥8♥9♥5,
爱因斯坦父亲在德国的生意失败了
Einstein's father's business in Germany had failed,
他们家就搬到了北意大利
and the family had moved here to northern Italy.
年轻的爱因斯坦喜欢在这些路上漫步
Young Einstein loved wandering these roads and
让他的思绪自♥由♥地探索
giving his mind free rein to explore.
这里有些东西是永恒的
There's something timeless about this place.
自爱因斯坦早年的白日梦
Nothing here has really changed
到现在这里几乎没有什么变化
since the time of Einstein's early daydreams.
有一天他开始思考光
One day, he began to think about light
以及光的速度
and how fast it travels.
每天我们都要测量
In everyday life, we always measure the speed
某个移♥动♥物体相对于其他物体的速度
of a moving object with respect to something else,
某样假设静止的东西
something that's presumably not moving,
某样在宇宙中静止的东西的速度
something in the cosmos that's not in motion.
比如我以每小时十千米的速度
For example, I'm moving about ten kilometers per hour
相对于大地移♥动♥
relative to the ground.
但就像我之前提到的大地也在运动
But as I mentioned earlier, the ground is moving.
地球正以超过每小时1600千米的速度自转
Earth is turning at more than 1,600 kilometers per hour.
当它围绕太阳公转时
While it orbits the Sun,
速度就超过了每小时10万千米
at more than 100,000 kilometers per hour.
而太阳又以每小时80万千米的速度
And the Sun is moving through the galaxy
在银河系中运动
at a half a million miles per hour.
而银河系又在宇宙中
And the Milky Way is moving through the universe
以每小时240万千米的速度运动
at nearly one and a half million miles an hour.
宇宙中没有静止
There is no fixed place in the cosmos.
万物皆是运动的
All of nature is in motion.
对于年轻的爱因斯坦来说
It was hard even for the young Einstein
都很难去想象某个绝对的标准
to imagine some absolute standard
来测量所有这些相对运动
to measure all those relative motions against.
就是这本书
This is the very book
这激励了少年时代的爱因斯坦
That inspired Einstein as a young boy.
给孩童的一本书改变了整个世界
Give a kid a book and you change the world.
甚至可以说是整个宇宙
In a way, even the universe.
看这里第一页上
Look at this-- the very first page,
记录了电流通过电线
it describes the astonishing speed
和光穿过空间时
of electricity through wires
惊人的速度
and light through space.
爱因斯坦回忆起少年时代
Einstein remembered what he'd learned as a child
从书里学到的知识
from this book,
也是此时此刻是他第一次
and perhaps, for the first time, right here,
思考人在达到光速时
wondered what the world would look like
看到的世界将会是怎样
if you could travel at the speed of light.
爱因斯坦越深入思考这个问题
The more Einstein thought about it,
他就越发困惑
the more troubled he became.
单是想象人以光速运行
If you imagine traveling at the speed of light,
就会发现矛盾重重
paradoxes seem to pop up everywhere.
爱因斯坦惊奇地发现
Einstein was shocked to realize
许多被人理所应当地认定
that so much of what had been uncritically accepted as truth
甚至连最权威的人物也同意的事情
by even the greatest authorities on the subject
其实大错特错
was just plain wrong.
当以高速运行时
When traveling at high speeds,
有一些公理是不可违背的
there are certain rules which must be obeyed.
爱因斯坦称之为相对论
Einstein called these rules "the principles of relativity."
试想一个妙龄少女骑着摩托车
Imagine that young woman who just blew past us
从我们身边呼啸而过
on the motorbike,
再试想她骑着车穿过整个宇宙
imagine she was riding her bike through the cosmos.
运动物体发出的光线以同样的速度传播
Light from a moving object travels at the same speed,
与该物体是静止还是运动状态无关
no matter whether the object is at rest or in motion.
这个女孩的速度不算入光的传播速度
Her speed is not added to the speed of light.
她的摩托车发出的光
The light from her motorbike
依然会以光速传播
still travels at the speed of light.
自然之律
Nature commands,
汝不可将我之速加诸光之速
"thou shalt not add my speed to the speed of light."
并且没有实体物质
Also, no material object
能以等于或超过光速的速度运行
can travel at or faster than the speed of light.
物理学不会阻止你
There's nothing in physics that prevents you
无限接近于光速地运行
from traveling as close to the speed of light as you like.
甚至是光速的百分之九十九点九都可以
99.9% of the speed of light is just fine,
但是无论如何
but no matter how hard you try,
你都无法达到光速
you never gain that last decimal point.
为了现实世界在逻辑上自洽
For reality to be logically consistent,
这要求有一个宇宙临界速度
there must be a cosmic speed limit.
这条鞭子发出的声音是因为它的尖端
The crack of that whip is due to its tip
运动的速度大于声音传播的速度
moving faster than the speed of sound.
这产生了冲击波
It makes a shockwave,
在意大利的郊外造成了微型音波爆♥炸♥
a mini sonic boom, in the Italian countryside.
打雷也是同样的道理
A thunderclap works the same way,
同样的还有超音速飞机发出的轰鸣声
and so does the sound of a passing supersonic jet.
为什么可以超越声速
So why is the speed of light