But the reality is that is less than five percent of the mass of the universe.

但事實上，這些不到宇宙質量的 5 %。

The other ninety five percent?

那剩下的 95 % 呢？

Well that's one of the biggest questions in science today, and what some of the greatest minds in astrophysics are trying to decipher.

那是當今科學界最大的問題，也是某些傑出的天體物理學家想破解的問題。

The hunt for dark matter has spanned decades and though we can't see it, smell it, feel

暗物質已經持續尋找數十年，雖然我們看不到、聞不到，感受不到

it, taste it, or hear it, we can see its gravity impacting other things.

嘗不到、聽不到，但我們發現它的重力在影響其他事物。

So if we only really know five percent of the story, discovering this elusive dark matter

因此，如果我們真的只知道整體的 5 %，那發現這難以捉摸的暗物質，

would unlock an entirely new understanding of everything and everyone in our known universe.

將解開已知宇宙中，對每件事和每個人的全新理解。

So how close are we to finding dark matter?

那麼，我們快找出暗物質了嗎？

If you're not really familiar with dark matter, let me get you up to speed on what we know so far.

如果你對暗物質真的不太熟悉，讓我快速解釋目前為止我們所知的事。

What we know is it exists.

我們知道它真的存在。

And that's about it.

這就是全部。

No, seriously.

我是講真的。

But there are a few things we are at least confident about:

但我們對某些事稍微有信心：

Dark matter is this really mysterious, strange substance.

暗物質是種非常神秘、奇怪的物質。

It's amazing in some sense because it's all around us.

從某種意義上來說它很驚人，因為它就在我們身邊。

Right now, as I'm sitting here, a wind of dark matter is going through me.

就現在來說，我坐在這裡時，暗物質的風正吹過我。

It doesn't interact with me, which, at least, it doesn't interact with me much so my body

它不會與我互相影響，至少沒有影響我的身體太多，

doesn't realize it's there, the Earth doesn't realize it's there.

所以身體並不知道它在這，地球也不知道它就在這。

We are pretty sure it's a new particle.

我們非常確定暗物質是種新粒子。

If it were not a new particle, if there's something totally crazy, then science would

如果它不是種新粒子，如果其中有些非常瘋狂的東西，那科學

be revolutionized overnight in a way that it has never been in the history of mankind.

將以一種從未出現在人類歷史中的方式，在一夜之間徹底改變，。

And then finally we know a lot about what dark matter isn't.

而且，我們終於搞清楚什麼東西不是暗物質。

So there have been lots of different kinds of experiments that have looked and tried to discover what dark matter is and haven't found it yet.

所以，有許多不同類型的實驗在尋找且想發現暗物質，只不過還沒發現。

And so we've excluded a lot of possibilities.

我們也已排除很多可能性。

But why is this missing piece of our universe so important to find and understand?

但是，為什麼我們宇宙中缺失的這部分，如此重要到必須找出並了解？

It could be that someday if we could manipulate this stuff, we could actually use it as a source of energy or something.

如果我們可以操縱這些東西，可能有一天，實際將它用作能源或其他東西。

In the far future, there might even be a huge payoff for us if we could manage to do that.

在遙遠的未來，如果我們能設法做到這點，可能會有龐大的回報。

In the late 1900s when JJ Thompson discovered the electron in cathode ray tubes nobody knew what the electron was good for.

約瑟夫．湯姆森在 20 世紀後不久，在陰極射線管中發現電子時，沒人知道電子有什麼好處。

He just thought this was an interesting thing to study.

他只是想說研究這東西很有趣。

And now when we think about how we live our lives, we all go around all the time with

想想我們現在的生活方式，我們出門逛逛時，

our heads in our phones, which are packed full of devices that rely on the quantum mechanical properties of the electron.

頭總是盯著手機，而這些手機充滿依賴量子力學特性的電子。

And so although we haven't found dark matter yet, there's a huge amount of it out there.

因此，雖然我們還沒有找到暗物質，但那裡有大量的暗物質。

And understanding its quantum mechanical properties, who knows how it's going to change our lives?

而且了解量子力學的特性，誰知道它將如何改變我們的生活？

This is a puzzle that is being put forward by the universe to us.

這是宇宙向我們提出的一道難題。

I cannot think of anything else better to do with my time than to try to answer that puzzle.

在我的其他時間中，想不到比解開這難題還值得去做的事。

Even though we haven't seen it yet, there's a few key pieces of evidence we have found so far in the search for dark matter that tell us we're on the right track:

即使我們還沒看到暗物質，但目前尋找暗物質時，已找出某些關鍵證據，告訴我們走在正確的方向。

We are certain that dark matter exists because the evidence for additional mass in the galaxy is all over the place in astronomical observations.

我們確定暗物質真的存在，因為在天文觀測中，有證據表明在星系中有額外的質量遍布整個地方。

You can see the gravitational pull on stars and on galaxies, to even a lot more subtle

你可以看到恆星和星系上的重力，甚至是更微妙的東西，

things like you can see the relativistic effect of invisible clumps of dark matter causing light rays to bend.

像是你可以看到，由暗物質看不見的團塊，造成光線彎曲的相對論效應。

Most recently there have been beautiful observations using optical data and X-ray data looking

就近期來說，在研究重力透鏡效應時，使用光學數據和 X 射線數據得出很美的觀察，

at gravitational lensing to infer the distribution of matter in colliding clusters of galaxies.

以推斷出星系碰撞中的物質分佈。

But by far the smoking gun for dark matter is the Cosmic Microwave Background.

但到目前為止，暗物質確切的證據是宇宙微波背景輻射。

This is the earliest thing that we can see through our telescopes through light.

這是我們在光線中利用望遠鏡最早看到的東西。

It's basically a photograph of a moment in history after the Big Bang, when the universe was only three hundred and eighty thousand years old.

它基本上是大爆炸後，歷史上重要的照片，那時宇宙只有三十八萬歲。

It also shows temperature data, and when we measure the fluctuations in temperature, the position of the peaks can determine the ingredients of our universe.

它還顯示出溫度數據，我們在測量溫度波動時，波峰的位置可以找出我們宇宙的成分。

It shows that less than five percent of the total mass of the universe is made up of what we call “normal matter,” like visible stars, planets, and galaxies.

它表明在宇宙總質量中， 我們稱為的「正常物質」才不到 5％，如可見恆星、行星和星系。

Then twenty six point eight percent of the mass of the universe is dark matter and the rest is made up of dark energy.

此外，宇宙質量的 26.8% 是暗物質，剩下的由暗能量所組成。

If you asked me what dark matter was I'd say I have no idea.

如果你問我暗物質到底是什麼，我會說不知道。

If you ask me what dark energy is, you wouldn't be able to show that because it would be I have no bleep bleep bleep bleep idea.

如果你問我暗能量是什麼，你沒辦法顯示出來，因為我根本 #@!% 沒想法。

Which means we should just leave dark energy for another day.

這意思是我們將暗能量留到改天再說。

Now, the reason the CMB was so significant in proving dark matter exists is because when

目前來說，宇宙微波背景輻射對證明暗物質的存在非常重要，

we compare theoretical models with these peaks, there's an extremely compelling match, practically ruling out a universe without dark matter.

我們將理論模型與這些峰值比較時，有個非常引人注目的搭配，幾乎是排除沒有暗物質的宇宙。

So basically putting it all together, dark matter is the simplest explanation we have

所以基本上將它們放在一起，暗物質是我們最簡單的解釋，

that explains all of the data that we have from different types of observations.

解釋從不同類型的觀察中得到的所有資料。

To match these discoveries and observations, scientists came up with a theory for what dark matter could be: WIMPs.

為了匹配這些發現和觀察，科學家提出一個理論，關於暗物質可能為何：WIMPs。

WIMPs — which stands for weakly interacting massive particles, but of course, the name

WIMPs ——意思是大質量弱交互作用粒子，當然

WIMP is so cute that everybody likes to use it instead — are particles that are heavy,

WIMP 這名字很可愛，每個人都喜歡這麼說，而不是說沉重的粒子，

and that's where the “massive” comes from and “weakly interacting” means that they

正是「大質量」的來源，而「弱交互作用」的意思是，

have an interaction strength that's maybe around the electroweak force.

它們可能有圍繞弱電作用力的相互作用力。

WIMPs started being discussed sometime in the 1980s.

WIMPs 在 1980 年代某個時期開始受到討論。

They've really been dominating the conversation, I would say, until about the last five or 10 years.

我會說，直到過去五或十年，它們才真正主導一切的討論。

WIMPs are beautiful because they solve a lot of problems kind of for free.

WIMPs 很美妙，因為它們算是自由解決許多問題。

You don't add too much, you just get a lot of explanations for mysteries that we want to know.

你不用補充太多，只需要解釋我們想知道的神秘事物。

If we can find WIMPs, it's possible that that would then mean we have found dark matter.

如果我們可以找到 WIMPs，可能意味我們已經找到暗物質。

So scientists began planning and building a lot of different experiments to look for WIMPs, dispersed all over the world.

因此，科學家開始計劃和建立許多不同的實驗，來尋找分散在世界各地的 WIMPs。

Experiments look for dark matter in three ways.

實驗以三種方式來尋找暗物質。

You can make it, break it, or shake it.

你可以製作、破壞或震動它。

So the experiments that make it try to produce dark matter particles in ultra high energy collisions of proton beams and accelerators like in the Large Hadron Collider.

所以，這些實驗想在大型強子對撞機的質子射柱和加速器的超高能量碰撞中，產生出暗物質粒子。

And those experiments look for some evidence that dark matter particles were produced and flew out of the detector.

那些實驗想找出某些證據，證明暗物質粒子是從探測器中產生並飛出來。

The Large Hadron Collider is pushing particles together at such high speeds that when they

大型強子對撞機將粒子以超高速擠在一起，

slam into each other, the kinetic energy that breaks off can be frozen into matter to be studied.

當它們相互撞擊時，中斷的動能可以凍結成待研究的物質。

It's possible that these tests could generate something that matches the properties of dark matter.

這些測試可能會產生與暗物質相配的特性。

The second search method is called indirect detection — the “break it” method.

第二種尋找方法稱為間接檢測 —— 「破壞」方法。

This is when we observe dark matter in space, and since it is so far away from us, we are

這是在我們觀察太空中的暗物質時，因為它離我們太遠，

only seeing what is produced when dark matter particles are annihilating each other — which

我們只看到暗物質粒子互相消滅時產生的物質，

could happen if there's a high enough density of them.

如果它們密度夠高，就會發生這情況。

And finally, the “shake it” method is actually called direct detection —

最後，「震動」方法實際上稱為直接檢測 ——

because scientists theorize that dark matter may set off extremely sensitive detectors.

因為科學家推測暗物質可能觸發極其敏感的探測器。

I work on the DEAP experiment.

我在從事 DEAP (氬元素暗物質探測器) 實驗。

And we use a detector which has three and a half tons of argon and is located a mile underground in Sudbury Ontario, Canada.

我們使用的探測器有三噸半的氬氣，位於加拿大安大略省薩德伯里一英里的地下。

And what we're looking for is some evidence that a dark matter particle struck an argon atom and then that argon atom deposited the energy in the detector.

而我們在尋找一些證據，證明暗物質粒子撞擊氬原子，然後氬原子將能量儲存在探測器中。

And that produces a flash of light.

這樣就會產生閃光。

It takes months or even years to get the experiments going and they often run for month or years

實驗需要好幾個月甚至好幾年才能完成，他們經常運轉好幾個月或好幾年

just collecting the data that they need in order to see if the dark matter is there where they think it might be.

就為了收集他們所需的數據，來看看暗物質是否在他們認為可能存在的地方。

So with all of these different searches, and all these different methods, have we found anything close to WIMPs?

所以，藉著這些所有不同的尋找和方法，我們已發現任何接近 WIMPs 的內容嗎？

We've been looking for almost 25 years.

我們已經尋找將近 25 年。

And we haven't seen it yet.

但我們還沒有看到它。

That means that WIMPS are still allowed to be the answer. On the other hand,

這意味 WIMPS 仍然會是答案。 另一方面，

when you don't find something for a few years, then you start to think, "All right, well, maybe I'd to look in other places too."

當你好幾年都沒找到東西時，你會開始思考，「好吧，嗯，也許我該往其他方面看看。」

I think what we're seeing now is a push in that direction.

我認為目前是往那個方向在推進。

In fact, the search for dark matter is experiencing a major, exciting shift right now for the first time in decades.

事實上，尋找暗物質的研究在這幾十年來，經歷首次重大且令人興奮的轉變。

The search for WIMPs will continue, but scientists are clamoring onto the scene with new ideas for what dark matter could be, bringing the hunt to new corners of the universe.

未來會繼續尋找 WIMPs，但科學家正努力提出暗物質可能為何的新想法，將尋找之旅帶往宇宙的新困境。

Once you go beyond the idea of WIMPs and start thinking about other ideas for what dark matter could be, you find actually there's a lot of great possibilities.

一旦你撇除 WIMPs 的概念，並開始考慮暗物質的其他想法，會發現其實還有很多可能性。

There are very light-mass particles like sterile neutrinos, which is kind of a cousin of the

像惰性微中子這樣非常輕質的粒子，它是微中子的一種表親，

neutrinos that are part of the standard model, or axions, this is kind of a very, very, light particle that explains certain mysteries for the strong nuclear force.

為標準模型的一部分，或是軸子，一種非常非常輕的粒子，用來解釋強核力的某些謎團。

One thing I'm actually really excited about is looking for dark matter through new forces.

我真正感到興奮的一件事是，透過新的力來尋找暗物質。

I think this is an avenue that is a relatively modest mathematical change to the theory,

我認為這方法對理論來說，是用相對適度的數學來改變，

that opens up a whole new range of different experimental handles.

開闢出一系列全新不同的實驗手段。

You could imagine that it's actually something to do with extra dimensions of space where

你可以想像它實際上與額外的空間維度有關，

at every point in space there's a different direction that we can't see because our eyes

空間中每個點都有不同的方向是我們看不見的，

don't know how to look in it, but you can actually send energy into it and you can have particles that live in it.

因為我們的眼睛不知道怎麼看，但其實可以將能量送進去，就可得到存在其中的粒子。

I'm really interested right now in the possibility that dark matter might actually interact with electrons.

對於暗物質可能確實與電子相互作用，我現在真的很感興趣。

And so I'm focusing on looking at searches using an alternate signal.

所以我專注使用替用信號檢查搜索結果。

And I think that that's kind of a trend for a lot of experimentalists: is we're thinking about how can our experiments do more?

而我認為這對許多實驗主義者來說是種趨勢：我們在思考實驗如何做出更多事？

How can we test other possibilities?

我們要如何測試其他可能性？

These are just a handful of new theories — there are so many more, with great names like fuzzy dark matter.

這些只是少數幾個新理論 —— 還有更多理論，名字也很棒，如模糊的暗物質。

Or, what if there was a periodic table of dark matter just like what we have for elements?

或者，如果說有個暗物質週期表，就像元素週期表一樣呢？

Testing these new theories can be folded into existing experiments or drive completely new ones.

測試這些新理論可以融入現有實驗或推動全新實驗。

Other ideas are actually even more exotic.

其他想法的確比較奇特。

You could imagine that you're going to use gravitational waves to discover something about dark matter.

你可以想像用重力波來找出暗物質的某些東西。

Other advances are more in the way that we actually do analysis.

其他進步更多的是我們實際分析的方式。

So, there are things like machine learning that allow us to be very sensitive to tiny and very subtle signals that are buried in complicated backgrounds.

因此，機器學習讓我們對隱藏在複雜背景中，微小且非常微妙的信號非常敏感。

The machines can be trained to discover things that your eye wouldn't be able to pick out from a set of data.

可以對機器進行訓練，來發現眼睛無法從一組數據中挑出的東西。

So to recap: We know it exists.

因此概括一下：我們知道暗物質存在。

We've been searching primarily in 3 different ways for WIMPs, but haven't found them yet.

我們主要以三種方式來找 WIMPs，但還沒有找到。

In doing so, we've eliminated a lot of what dark matter is not — which is progress.

在這過程中，我們已排除許多不是暗物質的東西，而這就是進步。

And we have a bunch of new ideas to explore.

而且我們有一堆新想法值得探索。

So how close are we to finding dark matter?

所以，我們快要找出暗物質了嗎？

If the current round of experiments are going to be able to discover dark matter,

如果目前一連串的實驗有辦法發現暗物質，

and there's a good reason to think they might be, I think we would know in a couple of years.

而且有充分理由認為它們就是暗物質，那我認為在這幾年內就會知道。

On the other hand, if these experiments are not quite what we need, it could take longer than that.

另一方面，如果這些實驗結果不是我們要的，那可能需要更長的時間。

I'm an optimist.

我是樂觀派的。

I'll tell you I could find it tomorrow.

我會告訴你明天就會找到。

I might have already found it.

我可能已經發現了。

I've got two years of data in the can that I haven't look at yet.

我手上還有兩年的資料還沒仔細看過。

It may be right around the corner.

也許就快找到了。

The honest answer is we really have no idea, but it's exciting because we have a fighting chance of being really close.

坦白來說，我們真的不知道，但這令人興奮，因為我們有非常接近的一線希望。

It is a hugely exciting scientific question and there are great experiments taking data now.

這是讓人非常興奮的科學問題，而現在有大量的實驗在收集資料。

And big leaps forward in sensitivity.

敏感度會大幅提高。

So I think the chance that we discover dark matter in the next 10 years is good.

所以，我認為在未來十年很有機會找出暗物質。

I'm betting on it.

我打賭會找到。

When the discovery comes, it's going to be like a bolt of lightning and it's going to change everything.

找出暗物質時，它就像一道閃電，將會改變一切事物。

Thanks for watching and let us know in the comments what topics you'd like us to investigate in future videos.

謝謝觀看並在下方留言告訴我們，希望在未來的影片研究什麼主題。

If you want to watch more “How Close Are We?”, be sure to check out our our full playlist and don't forget to like, share, and subscribe.

如果你想看更多「How Close Are We」的影片，記得要來看看我們的播放清單，也別忘了按下喜歡、分享及訂閱。