了解宇宙是如何运行的（2010）

How the Universe Works S05E01

Part 6 April 18, 2021, 7:46 p.m.

But it turns out the moon is actually
月球实际上正在远离地球
moving away from the earth, and that's due to
这是由于月球和地球的潮汐隆起的相互作用
the interaction of the moon and the earth's tidal bulge.
由于地球的自转速度
The bulge of water pulled up by gravity
比月球的轨道快
sits slightly ahead of the moon
被重力拉起的水的膨胀位置略早于月球
because the earth spins faster than the moon orbits.
月球通过重力作用在凸起处
The moon pulls by gravity on that bulge
减慢了地球的自转
and slows the earth's rotation.
数十亿年来
Over billions of years,
这大大减缓了地球的自转速度
that has slowed the earth's rotation a lot.
我们过去的旋转速度要快得多
We used to be spinning a lot more rapidly,
可能是现在的两倍多
probably more than twice as fast as we do now.
但是，万有引力就像鞭子一样
But, like a gravitational whipline,
月球对凸起物的引力也会加速其轨道运行
the moon's attraction to the bulge also speeds up its orbit.
这个速度使月球的轨道变宽
This speed makes the moon's orbit wider,
使它离地球越来越远
pushing it farther and farther away.
这是一个非常小的量，所以它大约
It's a very small amount, so it's only about
只有3.8厘米，即大约是一英寸半每年
3.8 centimeters, which is about an inch and a half a year.
在数十亿年的时间里
Over billions of years,
月球将缩小到夜空中的一个小点
the moon will shrink to a dot in the night sky,
而地球的自转将变得非常缓慢
and the earth's spin will become so slow
以至于月球看起来就像在我们头顶上冻结了
that the moon will appear to freeze above our heads.
事实上地球被锁住的时刻将会到来
There will come a time where the earth is actually locked.
地球的一面对着月球的一面
One side of the earth faces one side of the moon,
两者将同步旋转
and the two of them will go around in lockstep.
所以到那时地球上只有
So there'll be one place on earth
一个地方能看到月球
where you can see the moon.
所以你可能会想，你只有在度假的时候
So you might imagine you'd have to go on some kind of, uh,
才能到那个真正能看到月球的地方
vacation to actually see the moon at that point in time,
但那将是很长一段时间以后的事了
but that's gonna be a long time from now.
所以……所以，你知道，呃，我还没开始
So ... so, you know, um, I wouldn't start booking
给你订票呢
your tickets quite yet.
这是月球的长远未来吗？
Is this the long-term future of our moon?
一些科学家设想了一个更戏剧性的结局……
Some scientists envision a more dramatic ending ...
月球可能会被烧毁
a death by fire that will destroy the moon
很可能还会毁灭地球上所有的生命
and, quite possibly, all life on earth.
这一过程始于太阳的膨胀
The process begins with the expansion of the sun.
地-月系统未来的实际历史
The actual future history of the earth-moon system
将取决于太阳
will depend upon the sun,
它可能产生非凡的效果
and it could produce remarkable effects.
随着太阳年龄的增长，它会膨胀
As the sun gets older, it expands,
用密度更大的太阳风填充太阳系内部
filling the inner solar system with a denser solar wind.
这风会阻碍月亮
This wind will impede the moon.
所以当月球绕地球运行时，就会有阻力
So as the moon orbits around the earth, there'll be drag.
太空中会有更多的东西
There'll just be more stuff in space
让月球延缓运行
for the moon to push against.
所以月球已经远离地球
So the moon has been moving away from the earth
数十亿年了
for billions of years.
也许在这一点上，它会开始回归
Maybe at that point, it'll start coming back.
这种新的向内轨迹是一个死亡螺旋
This new inward trajectory is a death spiral.
月球最终会螺旋地
The moon eventually is going to spiral
越来越靠近
closer and closer, and then,
最后由于重力的作用
because of the gravitational forces,
导致潮汐力将变得非常强
the tidal forces are going to be so strong, it's going to,
它会爆♥炸♥
essentially, explode.
月球，在离地球表面11000英里的地方
The moon, 11,000 miles above the surface of the earth,
穿过了一个无法回头的点
reaches a point of no return.
地球的万有引力最终压倒了它
The gravitational pull of the earth finally overwhelms it.
破碎的月球残骸
The fractured remains of the moon
形成了一个类似于土星的岩石碎片环
create a saturn-like ring of rocky debris.
有一个环环绕地球将是一个非凡的景象
Having a ring around the earth would be a phenomenal sight.
我很乐意看到
I would love to see that.
你抬头一看，就能看到戒指
You would look up, and you would be able to see the ring.
它与地球成一个角度
It would be at an angle to the earth.
如果你在地球上正确的位置
If you were at the right place on the earth,
你就能看到它，横跨广阔的天空
you'd be able to see it, broad, stretching across the sky.
我不知道白天是否能看到它
I don't know if you'd be able to see it during the day,
但是到了晚上，它将是
but at night, it would be
我能想象到的最壮观的景象之一
one of the most spectacular sights I can imagine.
但美丽很快就会变成恐怖的环雨
But the beauty soon turns to terror,
碎片将象雨一样落在地球上
as pieces of the ring rain down on earth.
我是说，那将会是一个很棒的景象
I mean, it's gonna be an awesome sight,
也是一个可怕的景象
a terrifying sight.
我的意思是，整个天空都会布满流星雨
I mean, the whole sky is going to be filled
就像阵雨一样划过天空
with raining meteors just showering through the sky,
它们会很大
and they're gonna be huge.
拉德博:最终，所有的物质
Radebaugh: Eventually, all of that material
都将被并入地球
will be incorporated into the earth, and now,
现在这两个在出生时分离的兄弟姐妹
these two siblings, separated at birth,
终于再次成为一个身体
now are finally again one body.
在大爆♥炸♥90多亿年后
More than 9 billion years
我们的太阳和我们的星球地球诞生了
after the big bang, our sun and our planet, earth, is born.
慢慢地，我们正在把复杂的联♥系♥拼凑起来
Slowly, we're piecing together the complex connections
将它与我们的生活和宇宙之外的事物联♥系♥起来
that bind it to our lives and to the universe beyond.