宇宙没有任何义务向你解释它的存在——奈尔·德葛拉司·泰森
宇宙诞生于大爆炸
The universe began itscosmic life in a big bang
那发生在大约140亿年前
nearly fourteen billion years ago,
自那之后 宇宙一直处于膨胀中
and has been expandingever since.
但它要膨胀至何处？
But what is it expanding into?
这是个复杂的问题
That’s a complicated question.
原因在于：爱因斯坦的广义相对论方程
Here’s why: Einstein’s equations ofgeneral relativity
将时间与空间描述为互相连接的
describe space and timeas a kind of inter-connected
宇宙织布
fabric for the universe.
这意味着我们所知的空间和时间
This means that what we know ofas space and time
只是宇宙的一部分 而并非游离其外
exist only as part of the universeand not beyond it. Now,
而随着物体的不断膨胀
when everyday objects expand,
它们移至更大的空间
they move out into more space.
但 如果空间
But if there is no such thing
没有膨胀的余地
as space to expand into,
这种膨胀的意义何在
what does expandingeven mean?
1929年 爱德温·哈勃的天文观测
In 1929 Edwin Hubble’sastronomy observations
给出了一个决定性的答案
gave us a definitive answer.
他测量了夜空
His survey of the night sky
发现所有遥远的星系在渐渐远离
found all faraway galaxies recede,
或者说远离地球
or move away,from the Earth.
并且星系越遥远 远离速度越快
Moreover, the further the galaxy, the faster it recedes.
我们如何解读这一现象呢？
How can we interpret this?
想象烤箱里的葡萄干面包在不断膨胀
Consider a loaf of raisin breadrising in the oven.
每颗葡萄干之间的面团
The batter rises by the same amount
膨胀的大小都一样
between each and every raisin.
假设把葡萄干想象为星系
If we think of raisins as astand-in for galaxies,
把面团想象为星系间的空间
and batter as the spacebetween them,
我们可以猜想随着星系间的空间
we can imagine that thestretching or expansion
不断扩张或膨胀 星系会彼此远离
of intergalactic space will makethe galaxies recede from each other,
对任一星系而言 遥远的星系比附近的星系
and for any galaxy, its farawayneighbors will recede a larger
在同一时间内
distance than the nearby ones
渐远的距离更远
in the same amount of time.
果然 广义相对论的方程式预测了
Sure enough, the equations ofgeneral relativity
膨胀与引力之间
predict a cosmic tug-of-war
一场宇宙级的拔河比赛
between gravity and expansion.
只有在星系间的
It’s only in the dark void
黑暗虚空 膨胀才获胜了
between galaxies where expansion wins out,
进而空间扩张了
and space stretches.
因此这就是我们的答案
So there’s our answer.
宇宙在向其本身扩张
The universe is expandingunto itself.
即便如此 宇宙学家们还是在
That said, cosmologists are
不断突破数学模型的极限
pushing the limits of mathematical models
以推测出 我们的时空之后
to speculate on what, if anything,
如果有的话 存在着什么
exists beyond our spacetime.
这些并不是无端的猜想 而是基于
These aren’t wild guesses,but hypotheses that tackle
科学理论“大爆炸”的假说
kinks in the scientific theoryof the Big Bang.
大爆炸理论预言
The Big Bang predicts matter to
物质作为一种稀薄的气体均匀地
be distributed evenly across the universe,
分布在宇宙中
as a sparse gas —
然而 星系和星球是如何形成的？
but then, how did galaxies and stars come to be?
膨胀模型描述了
The inflationary model
一个短暂的
describes a brief era
宇宙暴涨期
of incredibly rapid expansion
它把宇宙初期
that relates quantum fluctuations
能量的量子涨落
in the energy of the early universe,
与团状气体的形成相关联
to the formation of clumps of gas
后者最终形成了星系
that eventually led to galaxies
如果我们接受这个范本
If we accept this paradigm,
那它同样意味着我们的宇宙所代表的
it may also imply our universe represents
只是更大的宇宙实体中的一小部分
one region in a greater cosmic reality
而后者也处于无止境的 永恒的膨胀中
that undergoes endless, eternal inflation
我们对这个
We know nothing of this
推测的膨胀实体一无所知
speculative inflating reality,
除了数学上的预言外
save for the mathematical prediction
宇宙无休止的膨胀
that its endless expansion
也可能被一个不稳定的
may be driven by an unstable
量子能态驱动
quantum energy state.
但在很多局部空间
In many local regions, however,
可能由于随机因素能量稳定了
the energy may settle by random
并形成稳定的形态
chance into a stable state,
停止膨胀并形成“泡泡宇宙”
stopping inflation and forming bubble universes.
每个泡泡宇宙 我们的宇宙也是其中之一
Each bubble universe —ours being one of them
都有自己的大爆炸和物理法则
—would be described by its own Big Bang and laws of physics.
我们的宇宙是更大的多元宇宙的一部分
Our universe would be part of a greater multiverse,
在这个多元宇宙中 无休止的急速膨胀
in which the fantastic rate of eternal inflation
使我们不可能遇见邻近的宇宙
makes it impossible for us to encounter a neighbor universe.
大爆炸理论还预言 在早期热宇宙中
The Big Bang also predicts that in the early,
我们的基本力
hot universe, our fundamental forces
有可能统一成了一种“超级力”
may unify into one super-force.
弦理论为这种统一提供了解释
Mathematical string theories suggestdescriptions of this unification,
除了基本的亚原子结构——夸克和电子外
in addition to a fundamental structurefor sub-atomic quarks and electrons.
在这些模型中 振动的弦是宇宙的基本结构
In these proposed models, vibrating strings are the building blocks of the universe.
而与弦对立的模型已经被结合于
Competing models for strings have now been consolidated
一个统一的解释中
into a unified description,
这些模型表明这些结构可能会与
and suggest these structures may interact
一种叫做“膜”的巨大高维度曲面相互作用
with massive, higher dimensional surfaces called branes.
我们的宇宙就可能被包含于这样一张膜中
Our universe may be containedwithin one such brane,
漂浮在一个未知的高维空间中
floating in an unknown higher dimensional place,
我们戏称为“块” 或者说多维空间
playfully named “ the bulk, ” or hyperspace.
别的一些包含其他宇宙的膜
Other branes—containing other types ofuniverses—
可能共存于多维空间中
may co-exist in hyperspace,
邻近的膜甚至可能
and neighboring branes may even share
共用某些基本力 比如引力
certain fundamental forces like gravity.
永恒膨胀和膜理论都描述了一个多元宇宙
Both eternal inflation and branesdescribe a multiverse,
但永恒膨胀的宇宙是孤立的
but while universes in eternal inflation are isolated,
膜宇宙却可以互相碰撞
brane universes could bump into each other.
这种碰撞的回声可能出现在
An echo of such a collision may appear
宇宙微波背景辐射中——
in the cosmic microwave background
扩散在宇宙中的一种辐射
—a soup of radiation throughout our universe,
它是大爆炸时期的遗迹
that’s a relic from an early Big Bang era.
但目前为止 我们还没发现这种宇宙回声
So far, though, we’ve foundno such cosmic echo.
有人猜测 这些不同的多元宇宙假说
Some suspect these differing multiverse hypotheses
最终可能有一个共同的解释
may eventually coalesce into a common description,
或者被其他假说取代
or be replaced by something else.
目前 这些假说
As it stands now,
建立在对数学模型推测性的探究之上
they’re speculativeexplorations of mathematical models.
虽说这些模型是在科学实验的
While these models are inspired andguided
启发和指导下创建的
by many scientific experiments,
但迄今仅有极少的客观实验
there are very few objective experiments
能直接检测这些模型
to directly test them, yet.
在下一个爱德温·哈勃出现之前
Until the next Edwin Hubble comes along,
科学家们很可能会不断争论
scientists will likely be left to argue
他们彼此对立的模型的优雅性
about the elegance of their competing models…
并继续想象着
and continue to dream about what, .
宇宙背后 如果有的话 存在的事物
if anything, lies beyond our universe