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Just a few days before he died, Stephen Hawking submitted one last research paper. And now, it's officially public.
在离世几天前，史蒂芬·霍金递交了自己的最后一篇论文，现在，这篇论文公布于世了。
After making it through the peer-review gauntlet, the paper was published last week in the Journal of High Energy Physics.
经过了同行评议的考验，这篇论文于上周发表在了《高能物理学报》上。
And in it, Hawking and his co-author Thomas Hertog attempt to upend the one of the most popular theories of not just the universe, but the entire multiverse.
在这篇论文中，霍金和合著者托马斯·赫托格试图颠覆最知名的理论之一，该理论不仅与宇宙有关，也与整个多元宇宙有关。
Yeah. We're getting a bit brain-bendy here. Thanks to astronomical observations,
这里有点复杂，需要稍微解释下，通过天文观测，
we know that our universe's structure is surprisingly uniform given its size.
我们得以知道人类所处的宇宙，就其规模而言，其结构堪称十分均衡。
On a large scale, there's roughly the same amount of matter everywhere.
在宇宙的广袤空间里，几乎到处都有相同的物质。
To explain this, cosmologists introduced the idea of inflation around 1980.
为了解释这一点，宇宙学家于1980年引入了宇宙膨胀的概念。
It says that, almost immediately after the Big Bang, the universe started expanding faster than the speed of light.
该概念说的是，几乎在大爆炸发生后，宇宙就开始以比光速更快的速度进行膨胀。
And that's not allowed for stuff in space, but is allowed for space itself.
空间里的物质无法承受这种情况，但空间本身是可以承受的。
It doubled in size over and over again in a teeny tiny fraction of a second.
那时候，宇宙在极短的时间里就可以发生无数倍的剧烈膨胀。
Then, for some reason physics can't really explain, that super-fast inflation stopped.
然后，这种极速的膨胀戛然而止了，其原因，目前的物理学尚且无法解释。
At least, it did in our neck of the universe. According to an idea called the theory of eternal inflation, it's still going on somewhere.
但就是发生了这样的现象，宇宙永久膨胀理论指出，这种情况是会发生的。
The idea says that separate parts of space too far away for us to observe have continued to inflate.
该理论认为，在地球观测不到的遥远空间里，宇宙是持续膨胀的。
But other pockets have stopped inflating, too. So you end up with isolated bubbles of space or,
但也有一些空间停止了膨胀，所以最后的宇宙成了相互分离的空间，
whole other universes, in a giant, ever-inflating multiverse.
这些空间都处在一个不断膨胀的巨大多元宇宙中。
If that hypothesis is correct, it means there are an infinite number of universes out there,
如果该假说成立，那么就有无数个宇宙，他们彼此相隔甚远，
and they'd be so far apart that each would have its own laws of physics.
各自遵循不同的物理学原理运转着。
Now, if this sounds like the parallel universes that sometimes show up in science fiction, that's because that's kind of what they are.
到这里，如果大家觉着这些相互平行的宇宙是科幻片里才会出现的概念的话，那是因为这确实有点不切实际。
Infinite, coexisting universes would mean there'd be no real significance behind the laws that govern our reality.
倘若真有无限且共存的宇宙，那么地球所遵循的物理学原理也就没有实际意义了。
That includes the exact speed of light, the strength of gravity, or any of the other components of physics that allow us to exist.
其中就包括光的实际速度、重力的作用等我们赖以生存的物理学原理。
They'd be just one random version of the way things could have gone.
这些原理就只是万事万物运转方式的一个可能版本而已了。
The biggest problem with this multiverse idea, though, is that you can't really test it. After all, if there's an infinite number of universes,
多元宇宙概念存在的最大问题就是：根本无法验证其真伪，毕竟，如果真的有无限数量的平行宇宙的话，
then any experiment that made predictions about what the universe should look like would be guaranteed to find a match somewhere.
那么通过任何实验所做出的的宇宙究竟怎样的预测就会有另一个版本。
If everything is possible, there's no way to falsify your hypothesis.
如果一切皆有可能，就无法证实假说的真伪了。
Unsurprisingly, many scientists, Hawking and Hertog included, just weren't comfortable with this.
在霍金和赫托格意料之内的是：很多科学家都持反对意见。
The two were actually working on the problem for decades, but for this paper, they borrowed some newer, special math from string theorists.
过去几十年来，这两位科学家一直在研究这个问题，但在这篇论文中，他们还引用了其他弦理论学家所使用的一些时间更新、方法特别的数学方式。
These researchers are trying to pin down a single set of laws that govern everything in the universe,
他们两个试图确定一套规律，这套规律是宇宙中万事万物的根本规律，
which we don't have yet, but if we did, would help us understand the Big Bang.
虽然尚未证实这样一套规律的存在，但如果我们能确定，就能更好地理解宇宙大爆炸是怎么回事。
To make their calculations easier, Hawking and Hertog's math ignores the dimension of time,
为了方便计算，霍金和赫托格所运用的数学方法对时间维度忽略不计，
so that's not a perfect reflection of the real world.
所以这并不能反映真实世界的情况。
But other researchers have used it in their own work, so it's a decent estimate.
但其他科学家在自己的研究中考虑了时间维度，所以其估测更符合实际情况。
Their model suggests that, mathematically speaking, the multiverse doesn't have to be infinite.
他们的模型显示，从数学角度来讲，多元宇宙并不一定是无限的。
And any other universes that do exist have similar laws to our own.
而其他与我们共存的宇宙也遵循与我们类似的规律。
Their work also suggests that time itself didn't exist at the very beginning of our universe, which might be even weirder.
他们的研究还表明，在宇宙产生之初，是没有时间维度的，这就让问题显得更加奇怪了。
It's all theoretical for now, but if this hypothesis proves correct,
虽然目前为止，这还只是理论研究，但如果该假说为真，
studying the really early universe would allow cosmologists to understand a lot.
那么研究初期宇宙就能让宇宙学家了解得更多。
It would help them figure out where the laws of physics come from,
可以让宇宙学家得知其背后的物理学规律是从何而来的，
how they came to be what they are today, and whether they're unique among the multiverse.
如何形成今天这副模样的以及多元宇宙里是否有其他宇宙遵循这样的规律。
And also, whether the multiverse actually even exists. As of right now, though, we don't have the technology to test this.
此外，还可以得知多元宇宙到底是否存在，但就目前而言，我们的技术尚无法验证这一点。
So several of Hawking's cosmology peers are skeptical, and he and Hertog have also stated their ideas need further development.
说回刚才的故事：霍金的同行对霍金的观点持怀疑态度，而霍金和赫托格也表示过，他们的观点需要进一步验证。
Hertog believes evidence either supporting or refuting their work could be found in gravitational waves generated during our universe's inflation.
赫托格认为，可以通过引力波来验证他们的观点是否正确，引力波是宇宙膨胀期间出现的一种现象。
These are similar to the ripples in space-time generated by things like black holes, but they'd be much older and longer.
引力波就像是宇宙里的涟漪一样，它是有黑洞这样的东西形成的，但引力波的年代更为久远，波长更长。
That means we couldn't detect them with LIGO, the instrument we currently use to detect gravitational waves.
所以，激光干涉引力波天文台是探测不到引力波的。激光干涉引力波天文台是现在我们用来探测引力波的工具。
But the European Space Agency's Laser Interferometer Space Antenna, or LISA, should be up for the task after it launches in 2034.
不过，欧洲太空总署的激光干涉空间天线于2034年面世后就可以进行探测引力波的任务了。
Still, even that might not be enough. We really won't be able to get an accurate story of our origins
不过，即便这样，也还不够，我们还是无法准确地了解地球起源的来龙去脉，
until we can find that batch of equations people like string theorists are looking for:
除非我们能找到弦理论家这样的人所寻找的等式。
one that unites general relativity and quantum mechanics, or the physics of really large and the physics of the really small.
一个囊括了广义相对论和量子力学的等式，或者说，一个囊括了宏观与微观的等式。
Right now, those two theories don't play well together, but we need them to in order to describe the Big Bang,
目前为止，我们还无法将广义相对论与量子力学完美融合，但我们需要这两种理论才能得知宇宙大爆炸的来龙去脉，
which is simultaneously super massive and super tiny.
因为宇宙大爆炸本身就是宏观与微观的结合。
So we might be waiting a long time to learn exactly what's going on with this multiverse. Or if there even is one.
所以，我们需要很多时间才能准确地得知多元宇宙到底是怎么回事，或者说，多元宇宙到底是否存在。
But whether he turns out to be right or wrong, it's clear Hawking's work will continue to resonate with current and future cosmologists.
但无论霍金的这篇论文正确与否，很明显的一点是：霍金所做的工作将与现在和未来的宇宙学家产生共鸣。
And as a bonus, when he passed, Hawking also had several other papers in the publishing pipeline.
或许是为了告慰这位科学家，在他逝世之际，他的其他几篇论文也发表面世。
So even if this was the last one he submitted, there should be even more science to come.
所以，即便这是霍金先生所提交的最后一篇论文，在他之后，科学会不断向前发展。
Thanks for watching this episode of SciShow Space!
感谢收看本期的《太空科学秀》！
This paper might not end up in the cosmology hall of fame,
这篇文章或许不会最后无法为人称道，
but some of Stephen Hawking's other work has definitely changed how we think about the universe.
但霍金的其他杰作确曾改变了我们对宇宙的看法。
If you'd like to learn more about some of his biggest accomplishments, you can watch our episode all about them.
如果大家想了解更多霍金的伟大成就，我们的视频集锦中应有尽有哦！
