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Over the years, we've talked a lot about dark matter, and you can't blame us.
近年来，暗物质成为热议的话题，这件事儿不能怪我们。
Even though it exerts gravitational effects, this stuff is invisible in telescopes.
虽然暗物质会产生引力作用，但通过望远镜也看不到它。
And it's found all over the universe, but scientists aren't totally positive what it is.
宇宙里到处都可以发现暗物质，但科学家对暗物质并不是十分了解。
Dark matter is one of the coolest mysteries in astronomy, but it's also made many of you raise your eyebrows.
暗物质是天文学最神秘的未解之谜之一，但也引起了很多质疑。
Whenever we bring up dark matter, commenters ask why scientists are so stubbornly positive it exists.
每次我们提起暗物质，就总有人说科学家怎么这么顽固呢？怎么就这么肯定暗物质存在呢？
Like, why can't they just admit they're wrong about gravity?
有人会说，让科学家承认自己对引力的理解有错，就这么难吗？
The truth is, though, scientists have spent decades trying to alter gravitational laws to explain dark matter... without dark matter.
事实是：过去几十年来，科学家一直试图改变万有引力定律，这样就能解释暗物质了，或者说就能让暗物质不存在的这件事说得通了。
And while they have had plenty of successes, a recent paper says they're really likely to be wrong.
虽然科学家也曾多次成功过，但最近的一篇论文指出，暗物质很可能真的存在。
Like... this likely to be wrong. That's a lot of 9s.
比如，暗物质并不存在等等。
Lots of independent evidence points astronomers toward dark matter.
很多独立的证据都让天文学家认为暗物质是存在的。
The most famous comes from stars and galaxies.
最知名的证据来源于一些恒星和星系。
Some of them move too quickly, to the point that the gravity from visible matter can't be the only thing holding them together.
一些恒星和星系移速很快，速度快到只有可见物质的引力才能让它们聚合在一起。
Computer simulations of the universe's evolution also require dark matter to produce realistic results.
对宇宙演变过程的计算机模拟也显示暗物质必须要产生实际的结果。
And the Cosmic Microwave Background, temperature variations imprinted on the universe by the Big Bang, has patterns we can't make sense of without a bunch of the stuff.
而宇宙微波背景，也就是宇宙大爆炸给宇宙留下的温度变化，它的规模是我们所不能理解的，除非有一些物质存在。
Specifically, we need about five times more dark matter than regular matter.
准确的说，我们推演出来，暗物质的含量是常规物质的近5倍。
Which is the same amount we infer from those other methods.
这跟我们通过其他方法推演出来的含量是一致的。
So it's not like astronomers have been chomping at the bit to postulate what this matter is.
但这不是天文学家根据一丢丢证据就去对这种物质是什么做推测。
They have been forced to their current ideas by almost a century of measurements.
他们是在经过了一个世纪的测量后不得已才有了暗物质存在的想法。
Even if we keep failing to discover what exactly dark matter is, the case that it's there seems pretty solid.
虽然我们一直没能揭示出暗物质到底是什么，但暗物质存在已经成了板上钉钉的事儿。
Then again, to make dark matter work, we do have to make some pretty extraordinary claims.
所以，要让暗物质起到它所发挥的作用，我们确实必须有一些让世人瞠目结舌的说法。
Like, we have to conclude that there's five times more invisible stuff out there than what we can see.
比如，我们必须要下这样的结论：暗物质的含量是常规物质的近5倍。
So some researchers haven't given up on searching for alternate explanations.
所以一些研究人员还没有放弃寻找其他可能的解释。
One of the most famous is an astrophysicist named Mordehai Milgrom.
其中最出名的当属天体物理学家莫德采·米尔格若姆。
In the 1980s, he wondered just how much you would have to change our ideas about gravity to explain galaxies' behavior without dark matter.
上世纪80年代，莫德采·米尔格若姆如果要在没有暗物质的情况下理解各星系的行为，那么需要对万有引力定律做出多少改变才可以。
To figure it out, he invented the field of Modified Newtonian Dynamics, or MOND, and it's been growing since his initial papers.
为了弄清这个问题，他发明了修正的牛顿动力学（MOND）。而该动力学自从他首次发表论文后就越来越风靡。
Currently, gravity is explained by Einstein's spacetime-warping general theory of relativity.
目前，重力的存在可以通过爱因斯坦时空扭曲的广义相对论来解释。
Among many other things, it shows that gravity gets continuously and smoothly weaker as you get farther from an object.
通过爱因斯坦广义相对论可以得出多个结论，其中一个就是：离一个物体越远，它对你的引力作用就越小。
MOND is a little different. This method tweaks general relativity's mathematical approach to gravity.
修正的牛顿动力学却有些不同：它将广义相对论的数学手段转向了引力作用。
Near something massive, its predictions are pretty similar, but they're different as you get farther from something.
在离大质量物体较近时，它的预测就非常相似，而离的远一些的时候，结果就不同了。
Instead of gravity getting continuously weaker, MOND usually has what's called a fundamental acceleration scale.
根据修正的牛顿动力学，离得远一些的时候，引力不但没有变弱，反而有了一种基本的加速规模。
It's a sort of lingering gravitational effect where you wouldn't really expect one using general relativity.
这也是一种引力效应，却无需用广义相对论来解释。
So far, this new method seems like it can explain a lot.
目前为止，这个新方法似乎可以解释很多事情。
Many galaxies' motions fit MOND's predictions just as well as dark matter's, and simulations with MOND have even had success reproducing the universe's large-scale structure.
很多星系的运动方式都符合该动力学的预测，也符合我们对暗物质的预测。我们对该动力学进行的一些模拟甚至取得了成功，居然可以重新生成宇宙这样浩大的结构。
But the method still has plenty of problems.
但该动力学依然存在很多问题。
For example, it has trouble recreating those patterns in the Cosmic Microwave Background.
比如，它无法重新产生宇宙微波背景的规模。
And it can't really account for all the different ways we see galaxies behave.
它也无法解释星系所有与众不同的行为方式。
Some galaxies act like they have almost no dark matter in them, while others might be 90% dark matter or more, and MOND has trouble reproducing that variety.
一些星系的表现就好像其中并没有暗物质一样，而另一些星系可能就有高达至少90%的暗物质，而该动力学无法重新产生这样的区分度。
MOND also has issues with objects like the Bullet Cluster, an object some 3.7 billion light-years away.
该动力学也不太适用于子弹星系团。子弹星系团距离我们大概有37亿光年的距离。
There, gravitational effects seem to be completely separated from visible matter, as if there's dark matter in one place and matter in another.
在子弹星系团，引力效应似乎完全受到了可见物质的隔离作用，就好像一个地方有暗物质，而另一个地方有可见物质一样。
Some people would argue that general relativity and dark matter have had a decades-long head start, and that researchers will work out the kinks in MOND eventually.
一些人会认为，广义相对论和暗物质已经有了长达几十年的领先优势，他们还认为研究人员最后一定可以搞明白修正的牛顿动力学是怎么回事。
But others aren't so confident. Earlier this year, a team of astronomers searched for the fundamental acceleration scale by looking at the rotation rates of almost 200 galaxies.
但还有一些人信心不足。今年年初，一组天文学家搜寻了基本的加速规模，方式是观察近200个星系的自转速率。
And they found that MOND doesn't fit the data.
而他们的发现结果是：该动力学并不符合这近200个星系的数据。
No matter which specific model you're using, MOND would predict the fundamental acceleration scale should be the same throughout the universe.
无论用的是哪个模型，该动力学的结果都是宇宙各处会有一样的基本加速规模。
But this team found that different galaxies required a different scale, which kind of throws a wrench in things.
但该研究组发现，不同的星系需要不同的规模，这就产生了一些阻碍。
Of course, nothing in science is 100% certain. But the team's analysis says that the chance that MOND is still right is pretty slim.
当然了，科学也不是100%正确的。但该小组经分析认为，该动力学正确的可能性很小。
Like, about 1 in a hundred billion trillion, a number with 23 zeros in it.
比如，千万亿分之一的可能性。
Some scientists have disputed that extreme statement, saying there's far more uncertainty than the new paper claims.
一些科学家反驳了这个说法，认为这个说法太极端。他们觉得，这篇新发表的论文指出的不确定性还不够。
But possible is awfully far from 1 in a hundred billion trillion.
可能几率比刚才说的还要低。
Now, this all might have been the death of MOND once and for all, if another paper hadn't come out a few weeks later.
如果几周内，没有其他的论文发表，那该动力学可能就彻底糊了。
In it, a different group studied almost all of the exact same galaxies, but they analyzed the data in a slightly different way.
在这个问题上，另一个组织对同一群星系进行了研究，但他们用略微不同的方式分析了数据。
And they found clear evidence of a fundamental acceleration scale that worked for all of them.
他们发现有明显的证据表明，某个基本的加速规模对所有星系都适用。
It's not obvious what caused this difference, but it does mean that MOND isn't dead yet.
虽然这种差异的原因不太明显，但这表明该动力学还不是一无是处。
At least for now, though, the majority of astronomers and cosmologists do think dark matter is still the right approach, and they have decades of good evidence to support that.
至少目前来看，绝大多数天文学家和宇宙学家都认为暗物质是存在的，而且已有几十年的证据可以支持这种观点。
After all, on scales bigger than individual galaxies, MOND repeatedly fails while dark matter repeatedly succeeds.
毕竟，在比星系要大的维度里，该动力学屡战屡败，而暗物质却屡试不爽。
Researchers will keep looking into alternate explanations, but, at least for now, no other idea is anywhere near as successful as dark matter is.
研究人员会持续关注其他说法，但至少目前来看，暗物质存在这件事还是占上风的。
So we'll just have to keep looking. Thanks for watching this episode of SciShow Space, and thanks to all the commenters who asked questions and inspired this episode!
所以我们也只能观望了。感谢收看本期的《太空科学秀》，也要感谢评论的各位，感谢你们对我们节目的鼓励！
If you have a pressing space question or fact you think is really cool, go ahead and leave it in the comments.
如果您想问问题或者想推荐您觉得很酷的太空信息，可以留下评论哦。
We'll do our best to check them all out.
我们一定会竭尽全力为大家解答疑惑的。
If you want to make sure we see your question, though, you can go to patreon.com/scishow.
如果您想确保我们能看到您的问题，还可以登录patreon.com/scishow。
