transcript: 每个人都喜欢平行宇宙这个说法——
Everyone loves the idea of parallel universes - 也许它的诱人之处就在于你不但拥有两次机会，而且一切都不同了——
maybe it's the appeal of an ideal world where you have second chances and things turn out differently -
每个人都喜欢平行宇宙这个说法——
Everyone loves the idea of parallel universes - 也许它的诱人之处就在于你不但拥有两次机会，而且一切都不同了——
maybe it's the appeal of an ideal world where you have second chances and things turn out differently - 在另一个现实之中，你进了霍格沃茨魔法学校
an alternate reality where you do get into Hogwarts 在那里，《星战前传》没有拍
and the Star Wars prequels aren't made 在那里，你终于只试了一次就成功地把不对称的USB插头插了进去
and you finally plug in your asymmetric computer cord correctly on the first try 但是在科学中，如此令人神往的景象真有一席之地吗？
but is there really a place in science for such wistful speculation? 我的意思是，如果“宇宙”是一切存在着的事物
I mean, if "the universe" is everything that there is 它就不能有两个版本，对吧？
you can't have two versions of it, right? 否则，这一对儿家伙就应该是真正的“一切”
Otherwise the pair would really be everything 而你一开始称为“宇宙”的那东西却不是了
and what you started off calling the universe, wasn't. 这是个术语上的问题：物理学家们所说的“宇宙”
The problem here is terminology: physicists speaking informally often say "universe" 时常是对“可观测的宇宙”这个词的一种不正式的说法
when they really mean "observable universe" 也就是整个宇宙中我们目前为止所能看得见的部分
that is, the part of the whole universe that we've so far been able to see. 而谈论多个不同的可观测宇宙则是没有问题的
And it's perfectly fine to talk about multiple different observable universes - 比如，一个处在<u>我们</u>可观测的宇宙边缘的外星人
for example, an alien near the edge of OUR observable universe 能够看见整个宇宙中我们看不见的部分
will see parts of the Whole Universe that we cannot yet see, 因为那里发出的光还没来得及到达我们这里
because the light doesn't have the time to reach us yet 但是这个问题其实相当浅显，并不是物理学家们平时讨论“多个可观测宇宙”或者“多宇宙”时
but that's a well-understood question and not what physicists normally talk about 所指的东西
when they discuss multiple observable universes, or "multi-verses." 所以就让我们直说重点吧：在物理学中，“多宇宙”一词通常是指
So let's cut to the chase: in physics, the word "Multiverse" normally refers to 人们提出的三种互不相同且基本上互不联系的描述宇宙的物理模型之一——
one of three distinct and largely unrelated proposed physical models for the universe - 顺便一提，它们全都并未经过实验的检验或证实
none of which has been tested or confirmed by experiment, by the way. 这三种“多宇宙”是：
The three "multiverse" models are: 第一种：泡泡宇宙或婴儿黑洞中的宇宙
Type 1) Bubble universes or baby black hole universes. 这是最简明易懂的一种多宇宙；它基本的意思是
This is the most straightforward kind of multiverse: the basic idea is that 也许宇宙的另外部分离我们十分遥远，以至于我们永远也看不见它们
perhaps there are other parts of the universe which are so far away that we will never see them 或者，这些部分处于黑洞之中，所以我们也看不见
or are inside black holes so similarly we will never see them. 这种模型的提出尝试解释了为什么我们的宇宙如此善于
This kind of model was created as an attempt to explain why our universe is so good at 制造恒星、星系、黑洞和生命——正如这种观点所指出的那样
making stars and galaxies and black holes and life - as the argument goes 如果宇宙中每个这些彼此分离且互不可见的“泡泡”都有稍微不同的物理学定律
if each of these separate mutually un-seeable "bubbles" in the universe had slightly different laws of physics 那么按照定义，我们只能存在于
then by definition we could only exist 拥有允许我们生存的适当物理定律的那一个之中
in one that had the right physical laws to allow us to exist. 就像，我们必须存在于能形成地球的宇宙之中
like, we have to exist in the universe where the earth can form 因为如果地球没有形成的话，那我们现在就不会在这里了
because if the earth couldn't be formed, then we couldn't be here 如果这种逻辑说服不了你，不要太担心
If you're not convinced by this logic, don't worry too much; 因为还没有任何实验依据能够支持这种多宇宙的说法
there's not yet any experimental evidence for this kind of multiverse. 第二种：膜和额外维
Multiverse type 2) Membranes and extra dimensions. 弦论无法在数学上预言我们所居住的宇宙的维度数目
Inspired in part by the inability of the mathematics of string theory 某种程度上，正是受此启发
to predict the right number of dimensions for the universe we observe, 弦论学家们提出了一个观点，即我们所认为的宇宙其实只是
string theorists proposed the idea that perhaps what we think of as our universe is actually 镶嵌在一个更大的九维“超宇宙”上的一张三维面
just a three-dimensional surface embedded within a larger super-universe with 9 spatial dimensions. 就像报纸的每一页都是
Kind of like how each page of a newspaper 镶嵌在我们的三位世界中的一个二维平面一样
is its own two-dimensional surface embedded within our three-dimensional world. 并且，当然，如果空间有九个维度而不是三个
And of course, if space had 9 dimensions rather than 3, 应该就存在足够的空间来使其他像我们的一样的三维面
there'd be plenty of space for other three-dimensional surfaces that appeared like ours, 作为它们自己眼中的宇宙而存在
to be universes in their own right, 但是，就像报纸的每一页一样，它们其实都是一个更大的整体的一部分
but, like the pages of a newspaper, were actually part of a bigger whole. 这种平面称为“膜”
These kinds of surfaces are called "membranes" or "branes" for short. 提醒一下，这种多宇宙也没有任何实验证据
And as a reminder, there is not yet any experimental evidence for this kind of multiverse. 第三种：量子力学的多世界图像
Multiverse type 3) The many-worlds picture of quantum mechanics. 令人诧异的是，物理学家至今还不能完全理解量子力学中的波函数坍缩是如何发生的
Surprisingly, physicists still don't fully understand how the collapse of the wavefunction in quantum mechanics happens, 多世界假说尝试着对此做出了一个诠释，它提出每条可能的
and the many-worlds hypothesis makes an attempt at explanation by proposing that every possible 宇宙时间线都是真实的，它们都以一种更大的、有更多分支的方式运行
alternate timeline for the universe is real and they all happen in an ever-larger, ever-branching way. 就像宇宙的一场自由路线的探险，所有可能的事件都会发生
Like, a universal choose-your-own-adventure where every possible story happens! 如果事实正是如此，我们可能无法意识得到，因为我们被困在了
If this were the case, we might not realize it because we'd be stuck living out just one 可供选择的无数种生活的其中一种里
of the infinitely many possible lives available to us. 某种意义上，多世界理论与泡泡宇宙模型有些相似
In some ways, many-worlds is similar to the bubble multiverse model 它们都认为：“一切能发生的事情都会发生
by proposing "maybe anything that can happen, does. 而我们只是恰好处在了那条能让我们存在的事件线上”
And we just happen to exist in the series of happenings that were necessary for us to exist." 如果你还是不相信这种逻辑，别着急
If you're still not convinced by this logic, don't worry: 这种多宇宙理论同样没有任何实验证据
there is not yet any experimental evidence for this kind of multiverse. 当然，如果你想让自己的想象力变得丰富一点，你也可以把这些模型中的几个组合起来
Of course if you want to get imaginative, you could also combine several of these models together 形成一个多多宇宙模型，它以一个新的超推测模型为基础
into a multi-multiverse, a new super-speculative model based, 而它自身则是推测性的、没有实验证实的模型
itself speculative and experimentally unconfirmed models. 但这并不是说我们不能验证多宇宙假说
But that's not to say we couldn't test the multiverse hupotheses. 比方说，如果我们的可观测宇宙
For example, if our observable universe were 真的是许多彼此不相连的泡泡或膜中的一个
really just one of many disconnected bubbles or membranes 并且如果它正巧与另一个泡泡或膜在过去的某个时间发生了碰撞
and if it happened to collide with another bubble or membrane some time in the past, 那么这种碰撞一定会对我们今天看到的夜空造成某些影响
then that collision would certainly have had some sort of effect on what we see when we look up at the night sky. 另一方面，多世界诠释可能很快就会得到检验
On the other hand, the many-worlds interpretation might be tested fairly soon 因为实验者们在实验室中操纵和控制
since experimentalists are becoming increasingly able to manipulate and control 更大的量子系统——那些位于量子力学领域与我们的日常体验的边界处的系统——
ever-larger quantum mechanical systems in their labs - 的能力正在不断地提高
systems that approach the line between the quantum realm and our everyday experience. 所以，我们必须一如既往地记住，物理学是科学而不是哲学
So as always, we must remember that physics is science, not philosophy; 当我们尝试解释我们观察到的宇宙时，我们要首先认定
and in our attempts to explain the universe that we observe, we have to make claims that 它在理论上是可以检验的
it can in principle be tested - 然后检验它们！
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