了解宇宙是如何运行的（2010）

How the Universe Works S10E03

Part 6 Aug. 5, 2022, 5:04 p.m.

ZIP codes,
在那里 WIMP 碰撞应该更容易被发现
where WIMP collisions
should be easier to spot.
你可能会在一个地方看到 WIMP 碰撞的证据
One place where you might see
evidence for WIMP collisions
那就是系外行星的核心
is actually the cores
of exoplanets.
事实证明，系外行星可能是我们最好的暗物质探测器
Turns out exoplanets might
be the best dark matter
detector we have.
你可以利用围绕遥远恒星运行的巨大行星
You can use giant planets
orbiting distant stars
作为实验室来了解暗物质
as laboratories
to understand dark matter.
我们知道引力会吸引 WIMP
We know gravity
should attract WIMPs.
引力越大，聚集在一起的暗物质粒子就越多
The more gravity,
the more dark matter particl
come together.
科学家认为 WIMP 聚集在
Scientists suggest that WIMP
congregate inside the cores
银河系最大的气体行星的核心内
of the Milky Way's
largest gas planets.
在这些超大的气体巨行星中
In these super-sized
gas giants,
WIMP 可以碰撞、湮灭并释放出伽马射线
WIMPs could collide,
annihilate, and release
gamma rays.
如果这些 WIMP 正在聚集系外行星的质量中心
If there are these WIMPs
that are collecting
the centers
那么暗物质的湮灭
of mass of exoplanets,
the annihilation
of that dark matter
就会使这些系外行星升温
can heat those exoplanets up.
如果你有一个被 WIMP 加热的系外行星，听起来很有趣
If you have a WIMP-heated
exoplanet, and that's just fun
to say,
这个东西会很热
this thing is going
to be warm,
它会比空间的热量高，而空间是非常冷的
it's gonna be warmer
than the heat of space,
which is very cold.
所以你需要一个红外望远镜
So what you need
is an infrared telescope,
它能看到红外线，如果有足够的敏感度
something that sees
an infrared light
and is sensitive enough
就能够测量这些物体的温度
to be able to measure
the temperatures
of these things.
但像这样的专用望远镜要到2028年才能发射
But a dedicated
telescope like this
won't launch until 2028.
对于一些暗物质探测者来说，等待太久了
For some dark matter hunters
that's too long to wait.
他们认为，WIMP 确实有一个特征
They argue that WIMPs
do have one characteristic
可以让我们在地球上探测到它们
that should allow us
to detect them
right here on Earth.
探测 WIMP 的关键就在它们的名字里，那就是 W-I
The key to detecting WIMPs
is in their name,
it's the W-I.
即他们是弱相互作用，并不是没有相互作用
<注：W:weekly——弱 I:interacting——相互作用>
They're weakly interacting.
They're not not interacting.
它们确实相互作用，只是与物质的作用很弱
They do interact,
it's just very weak
with matter.
这意味着在极少数情况下
And that means that
there are the rare occasions
它会撞到正常物质的粒子
where it will smack
into a particle
of normal matter
然后我们就可以观察到一些影响
and then there are effects
that we can observe.
在意大利中部的格兰萨索，科学家们正在观察
Scientists in
Gran Sasso in Central Italy
watch for a spark of energy
WIMP 撞击正常物质原子时产生的能量火花
generated when a WIMP hits
an atom of regular matter.
他们的探测器是一箱超级冷却的氙气
Their detector, a tank
of super cooled xenon
建在地表下几千英尺的地方
built thousands of feet
beneath the Earth's surface
把探测器放在山下的好处是，你可以看到所有的
The beauty of putting
this detector under a mountain
is that you've got all of this
岩石和土壤，以及其他东西
rock and soil
and everything else
它们能阻挡很多背景噪音
which is blocking
a lot of background noise.
当你在寻找 WIMP 交互时
When you're looking
for a WIMP interaction,
你在寻找一些非常罕见的东西，一些非常微妙的东西
you're looking for something
that's very rare
and something very subtle,
所以你不希望有其他东西发生
so you don't want
other things going on.
你不希望其他粒子进来破坏你的实验
You don't want other particles
coming in and messing up
your experiment.
这些弱相互作用的大质量粒子会穿过这座山
These Weakly Interacting
Massive Particles will pass
right through that mountain,
然后如果它们撞到氙原子上，我们可以看到它
and then if they smack
into a xenon atom,
we can look at it and go,
“哎，那是暗物质粒子”
"Ah, that was
a dark matter particle."
探测到 WIMP 可能是暗物质存在的决定性证据
Detecting a WIMP
could be definitive proof
that dark matter exists.
2020年，科学家们在研究结果中发现了一些东西
In 2020, the scientists
spotted something
in the results.
但这究竟是难以捉摸的证据
But was it
the elusive evidence
还是恒星间的幽灵？
or a ghost among the stars?
[播放环境音乐]
[ambient music playing]
科学家们相信，他们可以通过探测 WIMP
Scientists believ
they can prove
dark matter is real
来证明暗物质的存在
by detecting WIMPs.
一项深埋在意大利一座山下的实验发现
An experiment buried
deep beneath
an Italian mountain
在一罐普通物质中纯液态氙
spotted unusual activity
in a tank of regular matter
有不寻常的活动
pure liquid xenon.
[爆裂声]
[popping]
所以 WIMP 探测器，比如 XENON1T
So a WIMP detector,
like the XENON1T,
要等待一个 WIMP，一个非常非常小的粒子
waits for a little WIMP,
tiny, tiny little particle
撞击正常物质的原子
to hit an atom
of normal matter,
这就会产生振动
and that creates a vibration.
我们可以看到整个液态氙
And we can see this entire
block of xenon shake
在亚原子碰撞中发生了一点点震动
just a little bit
from that little,
subatomic collision.
粒子碰撞产生的
The intensity
of the vibration
振动强度是至关重要的
from the particle collision
is critical.
理论上，WIMP 撞击氙原子应该会产生强大的冲击
In theory, a WIMP striking
a xenon atom should generat
a powerful shock.
XENON1T 检测到的振动太弱
The vibrations XENON1T
detected were too weak.
当 WIMP 通过时，它会撞向原子
When a WIMP comes through,
it smashes into the atom.
就好像有什么东西
It seemed like here
something was just sort of
rattling the electrons
在震动原子外面的电子
on the outside of the atom.
所以，不管是什么导致了这些探测结果
So whatever is causing
these detections was likely
都可能是比 WIMP 小得多的东西
something much smaller
than a WIMP.
[萨特]从表面上我们看这些实验结果……
[Sutter] Let's take
these results at face value
如果他们是正确的，这就告诉我们
It... If they're correct,
it's telling us
暗物质不是 WIMP
that the dark matter
isn't a WIMP,
而是更小物质
but something
much, much smaller
更轻的物质
and something
much, much lighter.
结果表明，撞击液态氙的实际上
The results sugge
that what hit the xenon
是一种更小的理论粒子，称为轴子
was actually a much
smaller theoretical particl
called an axion.
[布洛克]轴子是一种非常奇怪的粒子，非常轻
[Bullock] Axions are really
weird particles,
incredibly light.