外星世界（2020）

地球 数百万物种的家园
The Earth, home to millions of species.
但地球之外…生存着什么？
But what might live. . . beyond?
有无数行星遍布宇宙
There are countless planetsxa0 throughout the universe.
即使一小部分行星上存在生命
If life exists on only a fraction of them,
那么宇宙一定充满生机
then the universe must be. . . alive.
所有生物都有同样的需求
All living things have the same needs.
进食…
To feed. . .
繁衍…
reproduce. . .
和进化
and evolve.
通过将地球生物的规律
By applying the laws of life on Earth
应用到宇宙的其他地方
to the rest of the universe. . .
我们可以想象
it's possible to imagine
外星世界
what could live. . .
会有什么生存
on alien worlds.
所有生命形式都需要生活在行星上
All life forms need a planet to live on.
但是宇宙中有多少行星呢？
But how many planetsxa0 are there in the universe?
想想我们的恒星
Think about our star,
太阳
the Sun,
地球、火星、木星绕其飞行
with Earth, Mars, Jupiter orbiting it.
数百年来
For centuries,
人们自问 “那么其他恒星呢？
people have asked themselves, "What about the other stars?
它们是否也有行星？”
Uh, do they have planets as well? "
24年前
And 24 years ago,
我找到了一颗
I found one!
（智利 帕拉纳尔天文台）
迪迪尔·奎洛兹 是位明星天体物理学家
Didier Queloz is a superstar astrophysicist.
他因为在我们太阳系外 找到第一颗行星
He has won the Nobel Prizexa0 for discovering the first planet
赢得诺贝尔奖
beyond our solar system.
我发现那颗行星的时候28岁
I was 28 years old when I found the planet.
我即将拿到我的博士学位
I was about to finish my PhD,
我的博士导师把器材的钥匙给了我
and my PhD adviser gave me the key of the equipment.
在观测了飞马座51几次后
And after observing a couple of times, the star 51 Peg,
我意识到这颗恒星有情况
I realized that something was going on on that star. xa0
说实话 我那时候很慌张
And frankly, I just panicked at that time.
我以为设备一定出了问题
I thought something was really wrong with my equipment.
我越想搞明白 越是想不通
And the more I wanted to understand this, the less it made sense.
最后我只能相信 一定有一颗行星存在
Until the point I got convinced it must be a planet.
有可能那里有一颗行星
That's likely to be a planet over there.
也许会是一颗木星
Could be Jupiter over there.
很酷
It's pretty cool.
望远镜是看不到遥远的行星的
Distant planets are invisiblexa0 to telescopes
因为行星不发光
because they don't emit any light.
但一旦行星绕到恒星前面
But if a planet passes in front of a star,
它会留下细微的阴影
it casts a tiny shadow,
恒星的亮度会略微减弱
and there's a minuscule dimmingxa0 of the star's brightness.
当天文学家侦测到亮度减弱
When astronomers detect this dip in light level,
他们就找到了新的行星
they have found a new planet.
你们好
Hello, guys.
这里是望远镜观测的地方
Uh. . . Oh, hey. Here is what the telescope is looking at.
这是望远镜现在看到的画面
This is a picturexa0 of the telescope right now.
中间是我们的观测目标
Uh, in the middle, you have the. . . the target we're observing.
通过分♥析♥整个区域 处理数据
So, you analyze this whole field, you process the data,
如果你够走运 你能侦测到这个
and, um, if you're lucky enough, you detect this.
光通量有略微减少
There's a little bit of a decreasexa0 of the flux,
通过这个我能知道 有一颗行星围绕着这颗恒星运转
and this tells mexa0 that there is a planet orbiting that star.
我们知道宇宙中有大量行星
We know there are a huge numberxa0 of planets in the universe.
一定有无数种不同的生命
There must be a zillion kinds of different life.
我们想象一下 这是地球 在这里 好吗？
Let's imaginexa0 that this is the Earth, here. . .
假设一米代表20光年
Right? So, imagine that one meterxa0 is 20 light-years.
两米就是40光年
So, I've made two meters as 40 light-years.
飞马座51就在这里 第一颗行星就是在这里发现的
This is where you have 51 Peg, where the first planet was detected.
每一个小灯代表一颗
Each of these tiny lightsxa0 represents a star
被发现有行星围绕的恒星
where a planet has been found.
接下来的数年后
Over the next few years,
到处都有行星被发现
planets were turning up everywhere.
行星 无处不在
♪ Planets, planets everywhere ♪
现在看起来相当酷炫
It looks pretty cool right now.
一道恒星和行星组成的风景线
A horizon of stars and planets. . .
环绕周围
all around.
太阳系之外的行星被称为系外行星
Planets beyond our solar system are called exoplanets.
天文学家已经找到了 超过4000颗系外行星
Astronomers have foundxa0 over 4, 000 of them.
这个数量还在增加
And they keep finding more.
他们现在相信 宇宙中每一颗恒星至少有一颗行星
They now believe there's at leastxa0 one planet for every star in the universe.
这就意味着系外行星的数量有百万… 千万…亿万
That means overxa0 a million, billion, trillion exoplanets.
比地球上所有沙粒的数量还多
More than allxa0 the grains of sand on Earth.
一个巨大的舞台以供生命进化
A vast canvas for the evolution of life.
距离令人叹为观止
The distances are mind-boggling.
最近的系外行星离我们 有万亿公里之遥
The nearest exoplanetsxa0 are trillions of miles from us.
但维系地球的力量同样主宰着它们
But they're all subject to the same force that holds the Earth in place.
重力
Gravity.
想象一个双倍地球大小的世界
Imagine a world double the size of Earth,
重力是双倍
with twice as much gravity.
这是亚特剌斯
This is Atlas.
生命将如何适应这样的世界？
How would life adapt on such a world?
重力将植被留在地球表面
Gravity pulls vegetationxa0 to the planet's surface.
然而 种子可以漂浮在天空
And yet, seeds can float in the sky.
这是因为这里的重力非常强大
That's because gravity here is so strong.
空气分子紧密挤在一起
Air molecules are densely packed together. . .
创建出一层稠密的具有浮力的大气 种子可以在其间漂浮
creating a thick, buoyant atmospherexa0 for seeds to drift through.
只要有种子的地方
And where there are seeds. . .
就有空中食草兽
there are sky grazers.
拥有六个翅膀的巨大草食动物
Giant herbivores with six wings
在稠密的空气中翱翔
to ride on the dense pillow of air.
由于额外的重力
Because of the extra gravity,
它们的体重会是在地球上的双倍
they weigh twice as muchxa0 as they would on Earth.
但是它们不会从天空中掉下来
But they don't fall from the sky.
大气足够稠密 让它们保持在空中
The atmosphere is thick enough to keep them airborne.
无论是在亚特剌斯 还是在地球
Whether on Atlas or on Earth,
飞翔都是和重力的对抗
flying is always a battlexa0 to overcome gravity.
（意大利 加尔达湖）
也许你会说我和重力的关系有点复杂
You might say I have a pretty complicated relationship with gravity.
当你拼命往上爬的时候 你能真切感受到重力把你往下拉
And you can really feel that gravityxa0 is a force pulling you down as you struggle your way up.
但说到底 我的梦想一直是能够飞翔
But ultimately, my dreamxa0 has always been to be able to fly.
哇哈
Whoo-hoo-hoo!
滑翔伞最令我喜欢的在于 它是如此简单而直观
The thing I love most about paraglidingxa0 is that it's so simple and intuitive.
整个运动只是你和空气
It's just you and the air.
正如亚特剌斯空中食草兽
Like the sky grazers on Atlas,
滑翔伞运动员使用他们的伞翼 制♥造♥上升力
paragliders use their wingsxa0 to generate lift.
但地球上的大气不那么稠密
But the atmospherexa0 is less dense on Earth. . .
所以要保持在空中更困难
so it takes more effortxa0 to stay airborne.
绝大多数人不把空气看作物质
Most people don't see air as a substance.
但对我来说 当我在飞翔时
But for me, when I'm flying,
我会真正把空气当做流质 它在山谷间上升下降
I really see it as a fluidxa0 that's moving up and down the valleys
顺着山脊移♥动♥
and along the ridges.
在非常稠密的大气中飞翔会非常奇怪
It would be really weirdxa0 to fly in a very dense atmosphere.
你可以毫不费力地一直在天上滑翔
You could just be gliding aroundxa0 the whole time, effortlessly.
上升的最佳方式是找到上升气流
The best way to gain altitudexa0 is to find an updraft,
也就是人们所说的热气流
known as a "thermal. "
当你碰到热气流
When you hit the thermal, it's very similar
那种体验和搭乘电梯非常相似
to when you're in an elevator and it starts.
你感觉被推了上去
You feel a push upwards.
耶 这就对了
Yeah, there we go!
纯粹是自然的力量把我拉上去
Just the power of nature to pull me up.
当我飞翔的时候 我看到一只鸟在盘旋
When I'm flyingxa0 and I see a bird circling up,
这意味着那里有热气流
it means there must be a thermal there.
所以我们会一直寻找它们
So we're always constantly looking at them.
你能真切地感受到重力向下的拉力 和空气上升的推力之间的平衡
You can really feel the balance between the gravity pulling you down and the air lifting you up.
然后你可以利用身体的自重
You can then use your bodyweight to gain speed,
来获得速度 再利用速度制♥造♥更多能量
and use that speedxa0 to generate more energy
感觉你在空气中穿行
and feel that you're movingxa0 through the air.
也许地球上的重力 弱于亚特剌斯上的重力
Gravity may be weaker on Earth than on Atlas. . .