宇宙（2007）

The Universe S01E10

Part 2 April 22, 2021, 8:13 p.m.

大部分的光线都是黄色的
If the Sun were much hotter,
加果太阳变得更热的话
the predominant wavelength oflight would come out into the blue.
光谱显示或许会是蓝色的
Or even into the ultra-violet.
甚至是更深的颜色
And cooler stars emitmore red light.
而温度较低的行星释放红色的光芒
Small, cool, red stars,like Proxima Centauri,
微小而温度较低的行星
就像圣多利星，它最靠近太阳
the nearest star to the Sun,are known as "Red Dwarfs".
它被称作是红接星
They can be as little as1/10 the mass of the Sun.
它们只有太阳热量的1/2到1八。
With surface temperaturesthousands of degrees cooler.
表面温度要减少7000多度
Red dwarfs are the most commontype of stars in the Universe.
红接星是最普通的行星之一
There are many, many more of thesesort of very dim, red dwarfs
有很多很多，这样释放红光的行星
它们在宇宙空间里飞行
floating out in space than there arestars like the Sun.
和我们的太阳一样，在宇宙中运行
Of course, when youlook in the night sky,
当然了，当你观察天空的时候
you don't see the mostcommon kinds of stars,
你能看到这些很普通的行星
you don't see these red dwarfs'cause they're so faint.
但是无法看到红接星
You merely see the veryrare, very bright stars
你看到但是更加明亮耀眼的行星
that turn out to bevery, very far away.
而它们却是更加遥远的
还有一种行星
On the opposite endof the spectrum,
它们是大型，释放蓝色光芒的行星
are the large blue,main sequence stars.
蓝色主序星
Averaging a surface temperatureof 45,000 篎.
表面温度达到华氏温度45000度
They can be 20 timesthe mass of the Sun.
可以达到太阳温度的20倍
And 10,000 timesmore luminous.
要明亮一万倍
In the life and death of a star,size definitely matters.
在行星诞生和灭亡的过程里
行星的大小当然是最重要的
这是行星寿命的一个重要指标
Mass is the fundamental thing
which drives the life historyof a star.
行星加果越大的话
The more massive stars
live much shorter lives thanthe less massive stars.
寿命要比其它的行星小很多
And that's perhaps a littlebit strange sounding,
这听起来有．支奇怪
because the massive stars havemore fuel to burn
因为体积小的行星没有那么多能量
you'd think they'd live longer.
它们的寿命就更长些
So, it's counterintuitivethat more massive stars
所以可以推算出，体积更大的行星
will burn through their fuel
它们速度快逐渐燃烧
more quickly than thelower mass stars.
比慢的行星燃烧的要剧烈
Imagine two gamblers sittingdown at a blackjack table.
加果想象一下，坐在赌两个赌博人，局前
You would expect the one withthe most money, the most "fuel to burn",
你认为其中一个很有钱
而消耗最少的那个，会坚持最久
would last the longest.
但是加果是在赌大筹码呢
But what if the big-time gambleris making huge bets on every hand?
他每次出手都大胜而归
A gambler that is gamblingwith a lot more money
一个赌将10万美金
and putting down $10,000 at a time
这样会消耗得很快
is gonna burn through that moneymuch more quickly.
So the more mass you have, the highertemperature, the higher pressure,
拥有的物质越多，燃烧的越剧烈，温度越高
the higher the fusion rate.
表面的温度也越高
It goes much more quicklywith the more mass you have.
这样它就很容易消耗掉
And it's always just simply thecalculation: how much fuel do you have,
这是很简单的算数过程
你到底会有多少钱
and at what rate are youconverting it.
多少损耗，你能坚持住
The high-mass stars livetheir lives faster.
高消耗的人，会很快出局
They burn the candle at both ends,it's life in the fast lane.
她们会很快消耗光，入不敷出很快就出局了
A high-mass star could diewithin a million years.
某行星可能会在一百万年就会消失
A star 10 times as massiveas our Sun,
10倍大的行星可能是最耀眼的
might live for only1/1000 as long.
或许只能活一千分之一那么久
So our Sun will live for about10 billion years in total.
我们的太阳要活一千万年
A star 10 times as massiveas our Sun,
星星是太阳体积的10倍多
might live only10 million years in total.
或许只能活上一千万年
While massive stars have lifespansmeasured in millions of years,
很多行星的寿命都有上百万年
the lowest mass starsmeasure their lives
而有些行星甚至会达到数百万
in tens of billions, if not trillions,of years.
甚至数十亿年那么久
Every low mass star that hasever been born in the Universe,
宇宙中每天都有无数的行星诞生
and the Universe has been makingstars for more than 10 billion years,
宇宙的寿命有数百万年之久
所有的行星都进行这样的过程
all of those stars are stillin their infancy.
No such star that's ever been bornhas ever come close to dying.
有些行星濒临消亡的边缘
但是对于所有的行星来说
But for all stars,including our own Sun,
包括我们的行星
life on the main sequencecan't go on forever.
主序上的行星寿命可以永远的持续下去
It can only last as long as the starhas fuel to burn.
可以持续到行星燃烧的尽头
If it runs out of fuel,fusion stops and gravity... wins.
加果没有能量的话
停止燃烧的话，那么引力就在博弈中获胜
Gravity never gives up,
引力从来都没有放弃过
whereas fuel, of course,can run out after a while.
而能量却有一天会消失殆尽
And so the star and the climberboth have this terrible problem,
行星都有这样一个问题
that if they don't maintain their fightagainst gravity, they will end in death.
它们无法维持这样一个平衡
结局只有死亡
A cataclysmic death.
最终消失
Not only does the size of a starinfluence how long it will live,
不只是行星这样体积的星球
体积不只决定它寿命的长短
it also determines howit will die.
还会决定它加何消失的
Massive stars explode fromthe scene in violent fury,
大量的行星在这个过程里消失了
while smaller ones are doomedto slowly fade away.
而小的行星却注定要慢慢的消失
For 5 billion years,
经过五百万年
our Sun,a lower mass, middle-aged star,
我们的太阳已经是中年的行星了
has been happily burning throughits supply of hydrogen fuel.
它已经燃烧了大量的氢能量
Like a gambler slowly plowingthrough a pile of chips.
The gambler may sit there fora long period of time,
手里陡，慢慢的筹码就像是个赌徒慢的支付
just like a star burns its hydrogenfor a really long period of time.
However, at some point,you're gonna run out of money.
赌徒或许会坐在那里很长时间
Scientists predict that5 billion years in the future,
就像行星燃烧氢燃烧，需要漫长的时间
但是，她注定要消耗光自己的钱
our Sun will reachthis critical crossroads:
科学家预计
Its supply of hydrogen fuelwill have been completely exhausted,
在未来五百万年后
nuclear fusion will cease,
核能转化会逐渐停止
and gravity will beginto crush the star.
引力会渐渐的将行星炸掉
At that point the situationis desperate.
这样的话，情况就很危急了
In order to survive, a sun-like starmust find a new source of fuel.
为了能继续延续它的生命
太阳必须寻找到另外的能量来源
It has helium on hand...
里面有另外的能量源泉
but in order to start burning helium,the core has to be
但是，为了能让它燃烧
核心的温度必须要达到10倍以上
10 times hotter than it was duringits lifetime burning hydrogen.
这样它才可以燃烧
It won't be able to fuse that heliuminto heavier elements,
并不是要变成另外一个更重的物质
like carbon and oxygen,
比加说氧等物质
until the core gets sufficiently hot.
只有内核达到足够的温度
And that's because it's harder to getthe helium nuclei close enough together
for the strong nuclear forceto take over,
让它们乏够的）在一起那是因为，足压力
grab them,and cause them to fuse together.
As it continues to contract inward,
这样核聚变才会发生
nature throws the star a lifeline.
这样才会将能源聚集在一起
The core actually becomessuperheated
随着它逐渐的向内部缩小
by the very gravitational pressurethat's trying to crush it.
自然将行星的光芒释放到极限
When it reaches 180 million degrees,it can start fusing helium into carbon,
内核变得更加炎热
开始逐渐形成碳元素
in a desperate gamble to survive.
它绝望的想要存活下来
So the desperate gambler might gotake out a loan on the house
赌博的．支数可能很大，超过房♥子价值
and get more money.
那是很大一笔钱
But in getting more moneyto burn through,
但是为了得到更大数目的钱
it's really just delaying the inevitable,which is to go bust.
这确实需要一段停滞时间，而不能过快
And for a star,the inevitable is to die.
而首先行星命运最终是要消亡的
The star which took 10 billion yearsto burn through its hydrogen,
行星的诞生需要耗费一千万年才能从氢中诞生
now powers through its supplyof helium in a mere 100 million years.
而现在它的消亡
只需要一百万年的时间
And then the action begins.
就是这样一个过程
It runs out of hydrogen...starts fusing helium.
当氢完全消耗光的时候开始失去热量
Runs out of helium...attempts to fuse carbon and will fail.
气温降低，碳的形成就会失败
But all the action,
但是所有的过程里
all the "what's going on now", happensin the last 10% of the star's life.
现在所进行的过程
都在延续行星的寿命
The searing heat of the helium burning
这里能量逐渐燃烧，气温不断升高
actually causes the outer layersof the star to swell.
这让行星不断的膨胀起来
At that point, the outeratmosphere of our star
这样的话，我们行星的外层空间里
will be held in by gravity so weakly
会脱离引力的束缚
that it'll start sort ofjust evaporating away.
很快、它就要脱离引力了
Through a series of what I call"cosmic burps", it will actually eject
这在理论上被称作，科斯尼燃烧
实际上将行星外层所吸引的气体
the outer envelope of gases, whichare only weakly held by gravity.
逐渐的脱离开
That'll send some shellsof gas outward
气体想外扩散
illuminated by the hotcentral star.
你会感觉到一种幻想
And that will cause what's calledthe "planetary nebula" phenomenon.
这就是一种行星的分离现象
Beautiful shells of glowing gassurrounding the dying core of our sun.
美丽的离散的气体