Name: This Missing Force Field Could Lead to a Dark Matter Breakthrough
Uploaded: 2020-08-31T19:35:08.000Z
Duration: 5 min

情態副詞

You're probably familiar with the standard model, a theory of fundamental particles and

你可能對標準模型很熟悉，這是一個關於基本粒子和的理論。

how they interact. These particles have counterparts that are mirror images, or opposite charges,

它們是如何相互作用的。這些粒子的對應物是鏡像，或相反的電荷。

or both. But in the '60s, we discovered particles that were flipped- image and charge versions

或兩者。但在60年代，我們發現了粒子 那是翻轉的影像和電荷版本

of each other didn't always behave how we expected. We've since adjusted our expectations,

彼此並不總是按照我們的期望行事。我們後來調整了我們的期望。

but even so, some of these particles still behave in a way we can't explain. It's

但即便如此，這些粒子中的一些仍然表現在我們無法解釋的方式。它的

what's known as the "strong CP problem," and it's a glaring flaw in the standard

所謂的 "強CP問題"，是標準中一個明顯的缺陷。

model. In order to understand the strong CP problem, there's a hierarchy of terms we

模型。為了理解強CP問題，我們有一個層次的名詞

need to make clear so we're all on the same page. First up, we need to review the four

需要說清楚，這樣我們才會心中有數。首先，我們需要回顧四個

fundamental forces. They are gravity, electromagnetism, the weak nuclear force, and the strong nuclear

的基本力，它們是重力、電磁力、弱核力和強核力。它們是重力、電磁力、弱核力和強核力。

force. With the exception of gravity, these forces are mediated by particles in the standard

力。除重力外，這些力都是由標準的粒子所介導的。

model called bosons. The way these forces affect decaying particles starts to get complicated

稱為玻色子的模型。這些力對衰變粒子的影響方式開始變得複雜起來。

when we talk about symmetry. Imagine an unstable particle that, through an electromagnetic

當我們談論對稱性時。想象一下，一個不穩定的粒子，通過電磁波

interaction mediated by photons, decays into “daughter” particles. If you were to take

由光子介導的相互作用，衰變為 "子 "粒子。如果你要把

that unstable particle and flip its charge, what's known as charge conjugation or just

顛覆其電荷，這就是所謂的電荷共軛或只是

C, the charge-flipped particle undergoes electromagnetic interactions in the same way as its antiparticle.

C、電荷翻轉的粒子與其反粒子一樣發生電磁相互作用。

The decay happens at the same rate and with the same properties, meaning electromagnetism

衰變發生的速度和性質都是一樣的，也就是電磁學。

has what's called "C-symmetry."  The same is true if you were to take that unstable

具有所謂的 "C對稱性"。  同樣的道理，如果你把那個不穩定的...

particle and flip all its spatial coordinates to make a mirror image of it, what's known

粒子，並翻轉其所有的空間座標，使之成為鏡像，這就是所謂的

as parity, or P.  A mirror particle will also undergo electromagnetic interactions

鏡面粒子也會發生電磁相互作用，作為奇偶性，即P。

in the same way, or symmetrically, to its regular self. So electromagnetism has "P-symmetry."

以同樣的方式，或者說對稱的方式，對其規律性的自我。所以電磁學具有 "P對稱性"。

And finally, electromagnetic interactions are the same whether we're going forward

最後，電磁相互作用是一樣的，無論我們是向前走還是向後走

in time or back, so they exhibit "T-symmetry." They also are symmetrical with any combination

在時間上或回溯上，所以它們表現出 "T對稱性"。它們也是對稱的任意組合

of C, P, and T, even all three together. So if you have a charge-flipped mirror image

的C、P、T，甚至三者一起。所以，如果你有一個電荷翻轉的鏡像。

of an unstable particle undergoing an electromagnetic interaction backward in time...you still know

一個不穩定的粒子在電磁作用下向後退的時候......你還知道嗎？

what you're going to get. Simple, right? Okay, stop, catch your breath. Let's all

你會得到什麼。簡單，對吧？好了，停下來，喘口氣。讓我們都

take a minute to sit with this new information, because I think you know what's coming next.

花點時間看看這些新資訊 因為我想你知道接下來會發生什麼事情

That's right, it gets more complicated. If our hypothetical unstable particle were

沒錯，它變得更復雜了。如果我們假設的不穩定粒子是 If our hypothetical unstable particle were

instead to undergo radioactive decay mediated by the weak force, then its mirror image version

而不是在微弱的力的作用下進行放射性衰變，那麼它的鏡像版本

wouldn't behave symmetrically every time. It would violate P-symmetry. This was first

不會每次都表現得很對稱。它將違反P對稱性。這是第一次

observed in 1956,  back when we thought parity conservation was the law. So you can imagine

觀察到1956年，當時我們認為奇偶性保護是法律。所以你可以想象

it was quite a shock when scientists observed two arrangements of cobalt-60 decaying differently.

當科學家們觀察到鈷-60的兩種排列方式衰變不同時，相當震驚。

Since then, it's been observed that weak interactions can also violate C- and T-symmetry,

此後，人們觀察到，弱相互作用也可以違反C對稱性和T對稱性。

and any combination of any two, though not C, P, and T altogether. So, after reworking

和任意兩個的組合，雖然不是C、P、T的全部。所以，經過重新設計

the math, the standard model today allows for weak and strong interactions to violate

數學，今天的標準模型允許弱相互作用和強相互作用違反。

all symmetries except CPT altogether.  Which gives rise to a new problem. We've observed

除了CPT以外的所有對稱性完全。  這就產生了一個新的問題。我們已經觀察到

weak interactions that violate CP-symmetry. It doesn't happen often, but it does happen

違反CP對稱性的弱相互作用。這種情況並不經常發生，但它確實發生了

nonetheless. In fact, it happens a lot more than we've seen charge-parity violation

儘管如此，。事實上，它的發生比我們所看到的電荷對等違反的情況要多得多。

in interactions mediated by the strong force. We've seen that a grand total of, drumroll

在由強勢力量調解的相互作用中。我們已經看到，總共有，鼓聲響起

please…. no times. Not once. Kind of disappointing, isn't it? The fact that the strong force

求你了......沒有次數。一次都沒有有點失望吧？事實上，強大的力量

should violate CP symmetry but hasn't as far as we know is called the strong CP problem.

應該違反CP對稱性，但據我們所知並沒有違反，這就是所謂的強CP問題。

But in science, the unexplained is where the fun begins! Because the strong CP problem

但在科學上，未被解釋的問題才是樂趣的開始!因為強CP問題

is such a mathematical improbability, we think there must be something else at play here.

是這樣一個數學上的不可能，我們認為這裡一定有別的東西在起作用。

In the '70s, scientists Roberto Peccei and Helen Quinn proposed that maybe there's

70年代，科學家Roberto Peccei和Helen Quinn提出，也許有

some undiscovered parameter, like a field that inhibits strong CP violation. If this

一些未被發現的參數，比如一個抑制強CP違反的場。如果這個

field exists, then there should be a particle called an axion to go with it. Axions should

場的存在，那麼就應該有一種叫做軸子的粒子與之配合。軸子應該

be chargeless, very light, and incredibly abundant. Hmm, a particle that's hard to

是無電的，很輕的，和令人難以置信的豐富。嗯，一個粒子，很難

find and doesn't interact with anything except through gravity? Sounds like another

找到並不與任何東西相互作用，除了通過重力？聽起來像另一個

candidate for dark matter to me. Indeed, since the 1980s, scientists have been hunting for

暗物質的候選者對我來說。事實上，自20世紀80年代以來，科學家們一直在尋找

axions in labs. As you might have guessed, we haven't found them yet, but we're still

實驗室裡的軸子。你可能已經猜到了，我們還沒有找到它們，但我們仍在

looking for them with research like the ADMX-G2 Experiment. Axions are not the only possible

通過ADMX-G2實驗等研究來尋找它們。軸子不是唯一可能的

solution to the strong CP problem, and when we eventually do figure out why this expected

強CP問題的解決方案，而當我們最終弄清楚為什麼這個預期的?

unexpected event...isn't...occurring, it'll be exciting to see where physics takes us

意外事件... ...是不是... ...發生，這將是令人興奮的看到物理學帶我們到哪裡去

If the search for axions and their relation to dark matter has piqued your curiosity,

如果尋找軸子及其與暗物質的關係引起了你的好奇心。

check out this Focal Point episode on how today's scientists are attempting to hunt

請看本期Focal Point的節目，講述當今科學家如何試圖獵取。

them down. Don't forget to subscribe, and keep coming back to Seeker for all of the

他們下來。不要忘了訂閱，並繼續回到Seeker來獲取所有的。

latest science news. Thanks for watching, and I'll see you next time!

最新科學新聞。感謝您的觀看，我們下期再見!