宇宙（2007）

The Universe S01E05

Part 3 April 22, 2021, 8:11 p.m.

Roche saw the Earth and the Moon as a solar system in miniature.
Roche说地球和月球是太阳系的缩影.
His idea was that the Earth starts out as a ball of gas
他的想法是地球开始时是个气体球,
and then cools and contracts and sheds a ring of gas,
在冷却收缩时,散发出气体环,
that then itself coalesces and forms the Moon.
然后环自身粘合形成月球.
But there are problems with this theory.
然而这个理论有问题.
For one our Moon has a much lower iron content than the Earth.
一个问题是月球的铁含量要比地球的铁含量小得多.
If the two bodies formed from the same materials,
如果两者是相同的物质组成的,
their basic composition should be the same.
那么它们的基本成分应该是一致的.
But they are not.
但是两者却不相同.
This and other inconsistencies
相互之间的矛盾
soon led fellow astronomers to quest for new ideas
很快就引导天文学家寻求新的思路
to explain the existence of the Moon.
去解释月球的存在.
In the last third of the 19's century
在19 世纪最后的叁分之一时期内,
advanced theories about the origin of the Moon started to emerge.
关于月球起源的先进理论开始出现.
In 1873 French scientist, Edouard Roche
1873年法国科学家Edouard Roche
proposed that the Moon simply formed alongside the Earth
提出月球只是在地球旁边形成的,
out of essentially the same nebular cloud of particles and gasses.
本质上是由相同的粒子和气体的星云构成的.
But this idea had a fundamental weakness.
但是这个主张有基本的弱点.
The Moon has a much lower iron content that the Earth.
月球的铁含量比地球低得多.
It's much less dense.
密度小许多.
The big thing that we remember about the Moon and its composition is
让我们想起月球和它的成分的要紧的事情是
that it doesn't have any iron core like the Earth does.
它没有地球一样的铁核.
So you look at the Earth, and there is a very large central area
所以你看,地球有个非常大的核心,
something like hefty inside of the Earth is iron, nickel-iron
地球重的内部是铁,镍-铁,
and that's metal of drain down to the center of the Earth in there.
金属流向地球的核心,在那.
Earth was hot when it formed at the beginning.
地球开始形成时是热的.
The Moon is more like just plain rock.
月球更多地只是象普通的石块.
Scientists initially deduce the mass of the Moon
科学家最初推断月球的质量
through observation and mathematical calculations.
是通过观察和数学计算.
If the Moon had formed from the same stuff that made the Earth,
如果月球是由与地球相同的物质形成的,
the iron content should be similar.
那铁的含量应该是相似的.
It was a hole in the theory Edouard Roche couldn't explain.
这是Edouard Roche无法解释的理论上的漏洞.
But another idea soon followed down the hills
但是另一个想法随着
of the co-accretion hypothesis.
共同成长的假设而来.
In 1878 George Darwin announced his fission theory of lunar origin.
1878年George Darwin宣布了他的月球起源的裂变理论.
This idea received some attention in part because Darwin had a celebrated father,
这个理论受到了部分人的关注,因为Darwin有个着名的老爸,
Charles Darwin, author of "Origin of Species".
Charles Darwin(达尔文),的作者.
In time though, George Darwin stepped out of this father shadow
George Darwin及时摆脱了老爸的影子,
and became known as England's leading expert on tides.
成为了英国着名的潮汐学领军专家.
And through extensive analysis of the tide-moon relationship
通过广泛分♥析♥潮汐-月球的关系,
George Darwin came to the realization
George Darwin认识到
that the moon is gradually moving further and further away from the Earth.
月球正逐渐地越来越远离地球.
It wasn't proved until 95 years later.
这在95年后被证实了.
When astronauts landed on the moon,
在宇航员登陆月球时,
they put little mirrors on the moon.
在月球上安放了一面小镜子.
And you can shine a laser at the Moon
可以将一束激光射向月球,
and the laser rebounds at the mirror come back
镜子将激光反射回来,
and you can actually measure the exact distance between the Earth and the Moon.
实际上这能够精确地测量地球和月球之间的距离.
And the rate at which this distance is increasing is 3.8 cm/year.
地月之间的距离正以每年3.8厘米的速度分开.
3.8 cm is about an inch and a half.
3.8厘米是1.5英寸.
If you made a movie extreme timate,
如果做一个动画来表示的话,
you will see the Moon moving away from Earth gradually.
就会看到月球逐渐地远离地球.
That's what we see nowadays.
这就是我们现在所看到的.
Darwin began to consider what would happen if we reverse the process,
Darwin开始考虑时间往后推将会发生什么,
if you run the movie backwards.
把动画往后倒转.
As we move backwards in time, and the Moon moves closer,
当我们把时间倒转,月球逐步靠近,
both the Moon's orbit and the rotation of the Earth
月球的运转和地球的运转
get faster and faster.
越来越快.
And so what will happen if then eventually the Moon must
所以当月球最终与地球融合时会发生什么,
coalesce with the Earth, and must, must take the Earth.
必须要考虑到地球.
The logical conclusion for Darwin
Darwin对此合乎逻辑的结论是,
was that a portion of the molten rapidly spinning Earth
快速旋转的地球融化的一部分
must have separated from the main mass
必定是与主体分离出来,
and spawn off to become our Moon.
产生了我们的月亮.
He immediately began work on mathematical calculations
他立即进行数学计算,
to reverse the trajectory of the Moon
逆转月球的轨道
all the way back to the Earth.
完全回到地球为止.
Frustratingly, he reaches a point where he gets almost to Earth
令人沮丧的是,他几乎得到了回到地球的那个点,
and then he couldn't work it out any further.
然而接着却无法更进一步进行下去.
The mathematic doesn't let you go any further.
数学无法更进一步进行下去.
What you get to as a point where the Moon is
得到的结果是月球
whipping around the Earth at a rate of
围绕着地球急速旋转,
five revolutions a day or six revolutions a day.
速度达到每天5圈或6圈.
So, it's just... zooming around the Earth.
所以,它只是...围绕地球急速移♥动♥.
Ok? And it's... it's about
是啊.它..在大约
5,000 miles away from the Earth.
距离地球5000英里的地方.
Still the mathematics did not allowed Darwin
数学仍然无法承认Darwin
to bring the two cosmic bodies into contact.
把两个宇宙天体结合在一起.
The fission theory was debated for decades,
分♥裂♥理论争论了数十年,
but scientists eventually concluded
但是科学家最后认定
that the relative movements of the Earth and Moon
地球与月球之间的相对运动
could not have resulted from it.
不是由此造成的.
The Earth would have be spinning too fast
地球旋转得太快,
to account for its present rotation rate.
以至于无法计算出现在的旋转速度.
The quest for an explanation of lunar creation continued
继续寻求月球诞生的解释,
and a new theory would soon originate with an American.
不久一个新的理论由一位美国人提出了.
In 1909 Thomas Jefferson Jackson See
1909年,Thomas Jefferson Jackson See,
was a U.S. naval captain
美国海军上校,
based at Mare Island near San Francisco.
驻扎在旧金山附近的麦尔岛.
His official job was to keep the standard time for the U.S. west coast.
他的官方工作是建立美国西海岸的标准时间.
But See was also a gifted scientist.
同时See也是位天才的科学家.
As a young man he had trained as an astronomer.
作为年轻人,他被培养成为天文学家.
He was one of the first Americans
他是美国首位天文学博士.
to actually get a doctorate in astronomy.
He went to Germany and got a Ph.D. in astronomy
他去过德国并得到天文学哲学博士,
which was, you know, almost unheard of back then.
那个,你知道吗,那时几乎闻所未闻.
The U.S. was still scientifically total backwater in the 1800s.
在19世纪,美国的科学还是死水一潭.
See's duty station, Mare Island, had an observatory.
See的驻扎地麦尔岛有座天文台.
And the captain's job allowed him plenty of time to theorize.
上校的工作有着充裕的时间去探讨理论.
He had spent time analyzing both the co-accretion and the fission hypothesis
他用尽了时间去探讨共同成长和分♥裂♥假设
regarding the origin of the Moon,
这两个月球诞生的理论,
and he wasn't convinced.
他不相信这些理论.
Gradually Thomas See developed a completely different idea.
Gradually Thomas See发展了截然不同的概念.
It came to be called "the capture theory".
这个概念被称为"捕获理论".
Essentially See theorized that the Moon had actually formed
See的理论在本质上表明月球实际形成
in a different part of the solar system from the Earth
在太阳系里与地球不同的地方,
that it orbited the Sun just like the other planets.
它围绕着太阳运转,就象颗其它的行星.
But that at some point it had moved too close to Earth
但是它有些地方太靠近地球,
and was captured by Earth's gravity.
并被地球的引力所捕获.
His idea was that there is something that he called the resisting medium
他提出在外太空,存在他称之为阻尼介质的东西,
in outer space, which we know is not there now.
其实我们现在知道那并不存在.
See never adequately explained what this resisting medium was supposed to be
See从来没有充分解释假设的阻尼介质
possibly tiny particles of matter.
是不是细小的物质粒子.
Regardless he was sure that no longer existed.
不管怎样他肯定那已经不复存在.
His idea is that for the Earth to capture the Moon
他的概念是地球捕获了月球,
the Moon would have to come in from far away
月球是来自远方,
and then it would hit this resisting medium and slow down and then
接着它碰到了所谓的阻尼介质,慢慢下降,接着
gradually get captured into an orbit,
逐渐被捕获进入轨道,
maybe not at once, it may take a little while
可能不是一次,可能有一小段时间
to get gradually be captured into Earth orbit.
逐渐被捕获进入地球的势力范围.
So it'd be like a bungee jumper jumping off a bridge, they go down, come back up
所以这就象悬崖弹跳者跳跃大桥,下去,上来,
not quite as far go down, come back up.
近距离的下去上来.
Then eventually they settle down at the bottom.
最后终于下降到底部.
Thomas See's capture theory would certainly explain the difference
Thomas See的捕获理论的确解释了
in iron content between the Earth and the Moon.
地球与月球两者铁核的不同.
If the Moon formed elsewhere its composition could be very different.
如果月球是在其它地方形成的,那它的成分就会有很大的不同.
On the other hand the notion that Earth gravity could capture and retain
另一方面,所谓的地球引力捕获和保留
such a large object was unlikely,
如此大的物体是不可能的,
since there is no obvious resisting medium
这是因为显然没有阻尼介质
to slows down an object as big as the Moon.
把月球这么大的物体的速度降下来.
All three theories have significant weaknesses.