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Whether you’re pondering alternate timelines that split into infinite possibilities,
无论你是正在思考有关交替时间线分化出无限多种可能性这一问题，
a completely different set of fundamental particles,
还是设想宇宙拥有一组完全不同的基本粒子，
or a reality where you came up with that hilarious comeback.
又或者是你想出了一种颇为滑稽，能够复原的现实，
Just in time!
那你可算是来对了！
You have to admit that the idea of parallel universes is pretty exciting.
毕竟你得承认，平行宇宙这个想法确实挺让人兴奋的。
And with modern advances in cosmology and particle physics,
我们的宇宙究竟是由什么构成的？
we’re refining our ideas of what exactly our own universe is made of,
宇宙是如何开始的？我们所在的宇宙之外，又或者之内，
how it got started, and whether there might just be another one, two, or infinitely many more out there. Or right in here?
是否还有另外一个，两个，甚至无穷多个宇宙？随着宇宙学和粒子物理学的进步，我们对这些问题的认识正在逐步刷新。
So, how close are we to finding a parallel Universe?
那么问题来了，我们离发现平行宇宙究竟还有多远呢？
When we consider what might lie beyond our observable universe, a few pretty cool theories emerge.
在讨论我们可观测的宇宙范围之外可能存在的事物方面诞生了几个非常酷的理论。
Many are not directly testable just yet;
尽管其中有许多理论当前都没有办法直接验证；
after all, if we could observe it, it would become part of our observable universe, right?
毕竟，要是都能观测到了，它就会成为可观测宇宙的一部分对吧？
But as it turns out, we have plenty of places to look in the game of hide-and-seek for other universes.
但事实证明，在和其他宇宙的捉迷藏游戏中，我们还有很多地方需要探索。
So, let’s start with the most basic, vanilla theory,
我们不妨从最基本的香草式（大家都能理解）理论入手，
and work our way up to the more “ghost-pepper-ice-cream-with-rainbow-sprinkles”-type ideas.
循序渐进地往更“撒了七彩糖针的魔鬼辣椒味冰淇淋”式（奇怪而高深）理论探讨。
There’s a type 1 multiverse, a quantum multiverse, a mirror universe, bubble universes, and baby universes inside black holes.
这些理论包括1型多重宇宙论，量子多重宇宙论，镜像宇宙论，泡泡宇宙论，还有黑洞内蕴含有小宇宙论。
The first proposal is what physicist Max Tegmark coined ‘the type 1 multiverse,’ Or what I like to call, “more of the same.”
第一种提法是物理学家马克斯·泰格马克提出的“1型多重宇宙”，我更喜欢称其为“多个相同宇宙”。
“One version is just to say that we can observe some finite region in the universe, but there's probably more out there.
“一种说法是，我们能观测到宇宙中某个有限的区域，但除了那个区域，宇宙中可能还存在更多区域。
So that sort of multiverse almost certainly exists.
这样一来，多重宇宙的存在几乎就是必然的了。
It just says that the universe is much bigger than the universe that we can see, but that's not that much of a surprise.”
这个理论的基本思想就是，实际的宇宙比我们所能看到的宇宙要大得多，但这其实算不上令人意外的理论。”
Okay, but if our own universe is defined by what we can observe,
好吧，那如果我们的宇宙是由我们所能观察到的事物来定义的，
what if it’s those observations themselves that spawn more universes?
要是其他宇宙是由观察到的这些事物本身生发出来的呢？
What if, every time you chose an ice cream flavor, for example,
打个比方，要是你选择一种冰激凌口味的时间，
thirty other universes branched off where all other possible outcomes came to fruition?
就有30个宇宙生发出来，所有其他可能都照进现实呢？
This is the next possibility, what you might call the “quantum multiverse”, where things get a little more interesting.
这就是第二种可能性，你可以称之为“量子多重宇宙”，在这种宇宙理论中，事情变开始变得有意思起来了。
"The multiverse where, whenever something in the quantum world happens, the universe kind of splits into two copies,
“在多重宇宙中，只要量子世界一发生变化，宇宙就会分裂成两个副本，
this is the so-called “many-world-version” of quantum mechanics.
这就是所谓的量子力学的“多世界版本”。
You know, in quantum mechanics, you can have version A of something and version B.
你懂的，从量子力学角度来看，一个东西可以有A，B两个版本。
And usually that's something like an electron,
通常这种情况都发生在电子身上，
but, you know, it doesn't weird us out that much that there's two versions of an electron.
但是，你也知道，我们并不会对电子有两个版本感到奇怪。
There are experiments that are now making two superposed, that is, kind of added-up Versions of complex molecules.
现在有一些实验正在模拟两种重叠的，也就是类似于叠加态的复杂分子。
There are people who are even trying the simplest viruses,
有人甚至在尝试对最简单的病毒进行多重版本研究，
and so as technology gets better, we might find that there's a limit to how big of an object we can make two versions of.
随着技术进步，我们可能会发现，能够拥有两个版本的物体的大小是有限制的，
Or there might not be.
但也有可能是没有限制的。
At some point, we might have two versions of a person.”
以此类推，我们人也可以有两个版本。”
But don’t get too excited to meet your new evil twin, or spock with a goatee, anytime soon.
但你可别兴奋过了头，以为很快就能跟你那邪恶的双胞胎或者留着山羊胡子的斯波克（出自《星球大战》）见面了。
Quantum phenomena are famously tough to understand and manipulate,
众所周知，量子现象很难理解，也很难控制，
because, by definition, observing them collapses their coexisting realities into just one: our own.
因为，首先从定义来看，对它们进行观察就会瓦解他们同时存在构成一个现实——也即构成我们的宇宙——的假设。
But what if we could observe quantum effects on other particles?
但如果我们能观察到其他粒子的量子效应呢？
Could there be clues about another universe lurking right under our nose?
会不会有另一个宇宙就潜伏在我们的眼皮底下呢？
And that brings us to the third idea: Mirror matter.
这就引出了第三种宇宙理论：镜像物质（镜像宇宙）。
“Mirror matter was originally hypothesized because of a discomfort with the fact that
“最初，学界是因为不满于弱力，宇宙中四种基本力之一，
the weak force, one of the four fundamental forces in the universe, actually prefers to couple to left-handed particles.
倾向于与左旋粒子配对这一现实才提出了镜像物质这一假设。
We realized that in order for this to be a valid theory, it probably shouldn't interact very strongly with our own universe.
我们意识到，为了让这一理论更站得住脚，这种物质可能不应该与我们自己的宇宙有很强的相互作用。
Mirror matter was actually one of the first and oldest possible candidates for dark matter.”
镜像物质实际上是暗物质最早、最古老的可能雏形之一。”
That’s what Leah and her colleagues at the Oak Ridge National Laboratory are busy hunting for,
而暗物质恰好也是橡树岭国家实验室的利亚和她的同事们正忙着追踪的东西，
using one particularly pertinent particle: the neutron.
她们追踪用的是与暗物质关系特别紧密的一种粒子：中子。
“What's really interesting about the neutron is because it is electrically neutral, it can undergo a process called ‘oscillation’.
“关于中子，真正有意思的是，它的带电性为中性，能发生所谓的‘振荡’。
This is a quantum mechanical phenomenon in which a particle can just move back and forth from one state to another.
振荡是一种量子力学现象，指的是粒子可以在两种状态之间来回切换。
So if there were some mirror partner to the neutron, some dark neutral twin,
这样一来，如果中子有镜像搭档，也即有同样不带电的暗黑兄弟的话，
then the neutron, in principle, could undergo an oscillation into that particle.
那么，原则上，中子就可以振荡成那种粒子。
and if so, that's something we can detect.”
这样一来，我们就能实现对镜像粒子的探测了。”
“Beyond this wall is a large liquid mercury target.
“这堵墙后面是一个巨大的液汞靶。
And through a process called spallation, it shakes free a bunch of neutrons from this very heavy mercury nucleus.
经过所谓的“分裂”，这个质量非常大的汞原子核会释放出大量的中子。
Once the neutrons are cooled down, they travel down these beam guides into the sample area of the instrument.
中子冷却以后，会沿着这些束流导管进入设备的取样区。
We use a wall made of a really thick boron carbide to absorb any neutrons that try to pass through.
我们用了一层非常厚的碳化硼来吸收任何试图穿过这个区域的中子。
If a neutron can oscillate into a mirror neutron, they'll pass through the wall.
但若一个中子能够振荡成镜像中子的话，它就能穿过这堵墙。
And then on the other side of this wall, those mirror neutrons then have a chance to oscillate back into regular neutrons.”
过了这堵墙之后，那些镜像中子就有机会振荡回正常中子的形态。”
“If we're able to confirm that what we see really acts like a mirror neutron,
“如果能够证实，我们看到的粒子在像镜像中子一样运动，
that would be very strong evidence that something like mirror matter, this mirror universe must exist.”
我们的实验就能有力地证明镜像物质，镜像宇宙之类的东西必定存在。”
While Leah and her team continue to search for that elusive mirror universe, this theory is still up in the air.
尽管利亚和她的团队仍在继续追寻神秘的镜像宇宙，该理论目前仍处于有待验证的状态。
But she can tell you one thing for sure: “I definitely don't have a pet demogorgon.”
但有一点可以肯定：“我绝对没有养恶魔王子（出自《龙与地下城》）。”
