了解宇宙是如何运行的（2010）

How the Universe Works S10E05

Part 5 Aug. 5, 2022, 5:05 p.m.

基于我们对粒子物理学
Based on our knowledge of
particle physics
和广义相对论的知识
and general relativity,
它就像一本宇宙如何运行的
it's like an instruction manual
说明书
for how the universe works.
重写它是一个激进的建议
Rewriting it is
a radical suggestion.
在大多数情况下，它与我们所看到的是相符的
For the most part,
it matches what we see,
但有一件事确实让它很纠结
but it does struggle
with one thing.
当宇宙从大爆♥炸♥中膨胀时
As the universe expands
away from the Big Bang,
你会直觉地认为引力
the intuitive thing you would
expect is for gravity to start
会把它重新拉回一起
pulling it back together again.
所以随着时间的推移
So over time, gravity
would just reverse that
引力会逆转，把所有东西都拉回来，回到一个单一的点
and pull everything back in,
back to a single point.
但我们在数据中看到的情况完全相反
But what we see in
the data is completely opposite.
我们看到的是，宇宙不仅是在
What we see is that
the universe is not only
继续膨胀
continuing to expand,
而且它的速度一直在越来越快
but it's speeding up faster
and faster all the time.
为了解释这一奇怪的现象
To explain
this weird phenomenon,
宇宙学模型依赖于
the cosmological model
relies on
一种奇怪的、未知的力量——
the existence of
a strange, unknown force --
暗能量的存在
dark energy.
暗能量是我在研究中
Dark energy is
the most perplexing
遇到的最令人困惑和神秘的东西
and mysterious thing I've
encountered in my research.
普莱特:暗能量是我们用来描述
PLAIT: Dark energy is a term
that we slap
宇宙膨胀加速这一观点的
on this idea that
the universal expansion
术语
is accelerating.
我们只知道这么多
That's about all
we know about it.
我们不知道是什么引起的
We don't know
what's causing it.
我们不知道它的行为
We don't know
how it behaves.
我们不知道它过去是什么样子
We don't know what
it was like in
也不知道它未来是什么样子
the past or what it's like
in the future.
所以我们称它为暗能量
So we just call it
dark energy.
它是看不见的——但它充满了整个宇宙
It's invisible --
it fills the whole universe
把星系推开
and pushes galaxies apart.
在某种意义上，它就像一个弹簧
In some sense,
it's like a spring,
一个收缩的弹簧，你要让它离开，但它想把所有东西
a contracted spring, and you
let it go, and it wants to push
都推开
everything away.
事情变得更奇怪了
And things
get stranger.
暗能量不会随着宇宙膨胀而稀释
Dark energy doesn't dilute as
the universe expands.
霍普金斯:当真空产生或膨胀时
HOPKINS:
As empty space gets created
与之相关的暗能量
or expands, the dark energy
associated with that
保持不变
stays the same.
它基本上填满了所有空的空间
It basically populates
all this empty space.
想象一下，我正在抽一桶水
Imagine I'm draining
a bucket of water,
水不知从哪里神奇地冒了出来
and water just magically
appears out of nowhere.
这就像宇宙膨胀时
That's like how
dark energy behaves
暗能量的表现
as the universe is expanding.
要标准宇宙学模型中
Dark energy
plays an important
暗能量起着重要的作用
role in the standard
cosmological model.
如果我们对它的理解是错误的
If our understanding of it
is wrong,
那么这个模型也是错误的
then so too is the model,
这意味着我们从宇宙微波背景辐射得到的宇宙年龄
which means the age of
the universe we get from the CMB
也是错误的
is wrong, too.
特马克:由于没有人知道暗能量是什么
TEGMARK: Since nobody has a clue
what dark energy is,
所以有很多不同的理论
there are a lot of
different theories.
但最大的问题很简单，它是恒定的吗？
But the biggest question of
all is simply, is it constant?
庞岑:我们对暗能量的标准假设是
PONTZEN: Our standard assumption
about dark energy is that
在整个宇宙的历史中
it's pushing apart the universe
它以相同的强度
with the same strength
throughout the history
推动着宇宙
of the universe.
现在物理学家们想知道这个想法是否错误
Now physicists are
wondering if that idea is wrong.
也许，在早期的宇宙中，暗能量的作用是不同的
Maybe, in the early universe,
dark energy acted differently.
嘿，你知道今天暗能量
Hey, you know that whole dark
energy thing that's messing
搅乱宇宙的事吗？
with the universe today?
也许过去它的确扰乱了宇宙
Maybe it messed with
the universe back then.
塞勒:暗能量对宇宙膨胀速度的影响
THALLER: It could be that dark
energy really has affected
可能比我们想象的要大得多
the rate of expansion a lot
more than we thought.
这将给我们关于宇宙的年龄
This is gonna throw a big
monkey wrench into our idea of
以及不同时期的情况的想法
how old the universe is
带来很大的影响
and what it was like
at different eras.
这个理论被称为新早期暗能量
The theory is called
new early dark energy.
DE RHAM:所以新的早期暗能量背后的想法是
DE RHAM: So the idea behind
new early dark energy is that
暗能量在宇宙非常早期的时期就存在了
dark energy was present during
the very early periods
但处于一种非常不同的状态
of the universe,
but in a very different state.
就像你可以想象水有
Just like you can think of
water being present in
两种状态
two states,
如果环境很热，它可以是液态水
it can be liquid water if
the environment is quite hot,
如果环境较冷
or it can be frozen water
它可以是冻结的冰
if the environment is colder.
普莱特:我们称之为相变
PLAIT:
We call that a phase change.
也许在宇宙早期
Maybe in the early universe,
暗能量也经历了相变
dark energy underwent
a phase change, as well.
以前不一样，现在也不一样
It was different before then
and acts differently now.
根据该理论，这种早期暗能量的高能状态
According to the theory,
this more energetic state of
将早期宇宙拉开的速度
early dark energy
pushed apart
比我们想象的要快得多
the early universe
much faster than we thought.
庞岑:所以这加速了我们宇宙的
PONTZEN: So that speeds things
up in the opening moments of
初始时刻
our universe,
当你解释宇宙微波背景
which starts to actually bring
things back into agreement
和距离阶梯测量时
when you look at
interpreting both
这实际上开始让事情
the cosmic microwave
background and the distance
回到一致的状态
ladder measurements.
普莱特:我们在宇宙中看到的事情之一是
PLAIT: One of the things
that we see in the universe
事物会随着时间而变化，密度会变化
is that things change with time,
density changes,
物质会变化、能量也会变化
matter changes,
energy changes.
为什么暗能量不会？