终有一天宇宙会毁灭
One day the universe will die.
那么是为什么 而且怎么毁灭？是否会永远消失？
But why? And how? And will the universe be dead forever?
我们又是怎样知道的？
And how do we know that?
首先 宇宙在不断增大
First of all, the universe is expanding.
不仅如此 增大的速度还在不断加快
And not only that, the rate of its expansion is accelerating.
其根源就是:暗能量
The reason: dark energy.
科学家们认为暗能量是一种在宇宙中蔓延的奇怪现象
Dark energy is a strange phenomenon that scientists believe permeates the universe.
直到1998年 我们才明白宇宙的运行就像是一颗
Until 1998 we thought that the universe must work a bit like
抛向天空的球
a ball that you throw into the sky.
一般球体向上运动 到某一点之后就落下
The ball moves up, but at some point it has to come down again.
但是宇宙的增长却是在加速
But the expansion of the universe is actually speeding up.
就像扔了一颗球 然后看着它飞得越来越快
That’s like throwing a ball up and watching it fly away
越来越快
faster and faster and faster.
那它的加速是怎么一回事？
Where is this acceleration coming from?
我们无从得知 但将它定义为“暗能量”
Well, we don’t know, but we call it “dark energy”.
爱因斯坦是最先提出的 随后认为这很荒谬
Einstein thought of it first and then decided it was stupid.
而如今 天体物理学家却觉得是可信的
Now, astrophysicists have decided it is plausible.
麻烦的是 这还仅仅处于理论层面 我们都不了解
Trouble is, this is all very theoretical, and we don’t actually know
暗能量到底是什么
what the properties of dark energy are.
各种各样的理论展现给我们宇宙的
But there are various theories and they lead us to three scenarios
三个结局
for the end of the universe.
第一:大撕裂
One: the Big Rip.
宇宙在出现时就在不断增大
Since its birth, the universe has been expanding.
不知为何 到处都有新的空间不断出现
For unknown reasons new spaces created everywhere equally.
不同星系之间范围都在增大 所以它们被隔离开
The space between galaxies expands, so they move apart.
星系里的空间也在增长 但是万有引力可以令
The space inside galaxies also expands, but here, gravity is strong enough
它们聚集在一起
to keep them together.
理论上，宇宙增长加速度会上升到
In the Big Rip scenario, the expansion accelerates up to a point where
万有引力无法吸引住的时候
space expands so fast that gravity can’t compensate for this effect anymore.
结果就是发生大撕裂
The result is a Big Rip.
首先 像星系这样大的物质会在空间快速
At first, only large structures like galaxies are torn apart,
增长时撕裂破碎
since space between the single objects expands very fast.
接着 像黑洞 恒星 和行星等主体部分消失
Next, big bodies like black holes, stars, and planets die.
这是由于所受的万有引力无法让它们聚集
Their gravity isn’t strong enough to keep them together,
所以都分散成小碎片
so they dissolve into their components.
最后 太空膨胀的速度会增大到比光速快
In the end, space would expand faster than the speed of light.
原子也会因此受到影响 不再聚集成团
Atoms would now be affected, and they would just disband.
一旦太空的增长速度大于光速 宇宙里所有的
Once space is expanding faster than light, no particle in the universe can interact
物质就不再相互影响
with any other particle anymore.
整个宇宙会分散成无数不相互影响的
The universe would dissolve into countless lonely particles that won’t be able to
不受时间限制的平行粒子
touch anything else in a strange, timeless universe.
你以为你会感到孤单！
Hmm, and you thought you felt lonely!
第二:热寂或者说大冻结
Two: Heat death or a Big Freeze.
简而言之 大撕裂和热寂的区别就是
In a nutshell, the difference between the Big Rip and heat death is that
热寂让物质一开始保持原形但相当长的时间之后
in a heat death scenario matter stays intact and is converted
随着宇宙的不断增大
over an incredibly long but finite period of time into radiation,
转化为辐射
while the universe expands forever.
那它是怎么形成的？首先来了解“熵”
But how does this work? Let’s talk about entropy.
就像在喝拿铁玛琪朵咖啡一样
Every system tends towards the state of highest entropy,
每个系统都趋向于最高熵的状态
like when we have a latte macchiato.
最初 拿铁玛琪朵咖啡都有不同的层次分布 但是慢慢地
Initially, it has different regions, but over time, they will
它会冷却然后融合 直到全部混为一体
cool down and disintegrate, until it’s uniform.
宇宙也是如此
And this also applies to the universe.
所以在宇宙越变越大的同时
So, while the universe gets bigger and bigger,
物质也在慢慢衰变与扩展
matters slowly decays and spreads out.
到达一定程度 即出现大量星体之后 会因缺乏
At some point, after lots of generations of stars, all the gas clouds necessary
星际云而无法形成星体 因此宇宙变暗
to form stars will be exhausted, so the universe will turn dark.
然后剩下的恒星会消失
The remaining suns will die;
几万亿年后 黑洞会因为辐散“霍金辐射”之光
black holes will slowly degenerate and evaporate over trillions of years
而慢慢退化消失
due to what’s known as Hawking radiation.
当退化完全之后 就只剩下一些光子和轻质粒子组成的气体
When this process is complete, only a dilute gas of photons and light particles
而它们也会退化消失
remains,until even this decays.
宇宙里的所有物质都会如此退化消失
All activity in the universe ceases at this point;
这时候熵达到最大 而宇宙也永远消失
entropy is at its maximum and the universe is dead forever.
除非……在理论上 有可能
Unless… theoretically, it might be possible
经历非常长的时间后
that after an incredibly long amount of time,
会因为形成“量子隧穿” 而出现熵的自发降级
there might be a spontaneous entropy decrease as a result of something called
最后形成新的“大爆炸”
“quantum tunneling”,leading to a new Big Bang.
第三:宇宙大收缩和大反弹理论
Three: Big Crunch and Big Bounce.
这是最令人振奋的一个说法
This is the most uplifting scenario.
如果宇宙中存在比想象中更少的暗能量 或者它随着时间减少
If there is less dark energy than we think or it decreases over time, gravity will be
那终有一天万有引力会成为最终支配宇宙的力量
the dominating force in the universe one day.
在几万亿年后 宇宙增长的速率
In a few trillion years, the rate of expansion of the universe
会慢下来直至停止
will slow down and stop.
然后 事情反过来了
After that, it reverses.
万有引力会让星系彼此吸引 合并 然后宇宙变得
Galaxies will race at each other, merging as the universe becomes
越来越小
smaller and smaller.
宇宙变得越小 意味着变得更热 温度会
Since a smaller universe also means a hotter universe, temperatures rise
即时上升
everywhere all at once.
在宇宙大收缩开始的十万年前 背景辐射会变得
One hundred thousand years before the Big Crunch, background radiation would be
比大多数星体表面热 这意味着
hotter than the surfaces of the most stars, which means that
星体从表面被烤熟
they would be cooked from the outside.
在大收缩的几分钟前 原子核被扯碎
Minutes before the Big Crunch happens, atom cores are ripped apart,
而特大黑洞将吞噬所有物质
before supermassive black holes devour everything.
最后 所有黑洞聚集形成一个特别巨大的
Finally, all black holes would emerge into a supermassive mega-black hole
包含了宇宙所有质量的黑洞
that contains the entire mass of the universe,
在大收缩的最后一分钟
and in the last moment before the Big Crunch
它会毁灭整个宇宙 包括自身
it would devour the universe, including itself.
宇宙大跳跃论认为宇宙
The Big Bounce theory states that this has happened a lot of times
在不断地循环着
and that the universe goes through an infinite cycle of
增长和收缩
expansion and contraction.
是不是很棒？
Well, wouldn’t that be nice?
那最后宇宙会发生什么？
So what will actually happen to the universe in the end?
热寂是最有可能发生的 但是在Kurzgesagt的我们
At the moment, heat death seems the most likely, but we at Kurzgesagt hope that
认为宇宙“永远消失”是错误的 它会一次又一次地重新开始
this “dead forever” stuff is wrong and the universe will start over and over again.
我们不能确定宇宙的结局是怎样 但是希望这个
We don’t know for sure either way, so let’s just assume
最令人振奋的结局是真的
the most uplifting theory is true.
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By the way, we have a Twitter account.
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