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研究地球内部的新方法 以及水母星系的最新研究进展 – 译学馆
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研究地球内部的新方法 以及水母星系的最新研究进展

A Better Way to Study Earth, and Lessons from Jellyfish Galaxies

开篇音乐
[♪ INTRO]
我们对地球的大部分了解
Most of what we know about the inside of our planet
源于对地表的观察以及对地球内部的研究
comes from looking down and studying Earth’s interior itself.
然而关于我们的地球家园 我们还有很多东西并不了解
But there’s still a lot we don’t know about our planetary home,
科学家们也在持续寻找更好的工具来帮助我们学到更多
and scientists are always looking for better tools to help us learn more.
而就在上周 一支物理学家团队宣称他们可能找到了一个新的方法
And just last week, a group of physicists announced that we might be getting a new one.
他们在发表于《物理评论D》的论文中表明
In a paper published in the journal Physical Review D, they calculated that a detector
他们正在建造的探测器将可以利用中微子探索地球内部
that’s already being built will be able to study Earth’s interior using neutrinos,
中微子是宇宙中最难以探测到的粒子
some of the most elusive particles in the universe,
它们每时每刻都会穿过我们的身体
which are constantly raining down on us from space.
我们从地震中对地球内部了解了很多
We learn a lot about the inside of our planet from earthquakes.
例如 根据测定的波的类型
For example, based on the types of ripples we detect from an earthquake,
我们能推断地震波是否穿过了一层液体
we can tell if it traveled through a layer of liquid.
通过对重力等数据的测量 我们可以知道地震波穿过的介质 根据这一点
By combining what we know about how ripples travel through matter with measurements of
科学家建立起了良好的
things like gravity, scientists have formed pretty good models
地球和其他行星地表之下的结构模型
of what Earth and other planets look like beneath the surface.
然而现今的方法仍然遗留了许多待解决的问题 比如不同的岩石层
But today’s methods leave a lot of unanswered questions still, like how different layers
是怎样移动变化才让热量流向地球内部的
of rock move and change to let heat flow through the inner Earth.
论文的作者们声称中微子可以对这一问题提供帮助
The authors of this new paper argued that’s where neutrinos can help: The way they travel
中微子在地球内移动的方式能给我们带来一个全新的了解地球内部结构的方法
through the Earth can give us a brand-new way of understanding its internal structure.
中微子是一种极小的粒子 几乎不会碰到其它任何物质
Neutrinos are tiny particles that hardly ever hit anything else, and they come in three
它有三种形态 叫做“味道”:电子中微子、μ中微子和τ中微子
types, called flavors: electron neutrinos, muon neutrinos, and tau neutrinos.
不过中微子不会一直保持一种形态
But a neutrino doesn’t always stay the same flavor.
当它运动时可以转换成其他的形态
It can switch between flavors as it travels.
尽管他们几乎不与其他物质直接作用
And even though they hardly ever directly interact with other matter, the density of
中微子周围物质的密度可以帮助我们判断它在各种形态之间转换的速度
matter around a neutrino helps determine how quickly it switches between flavors.
通常它们在筹密的物质之中 总是以电子中微子的形式存在
Generally, they spend more time as electron neutrinos in denser matter.
这支团队指出我们可以根据这个奇特的性质来了解地球内部
And the team pointed out that we can use this weird property to study Earth’s interior.
例如 若我们观测到 在穿过行星某一部分的中微子中 电子中微子含量越多
For example, if we see more electron neutrinos among the neutrinos that have passed through
那么我们就知道(行星)该部分的密度就更大
certain parts of the planet, we know those parts are denser.
这种说法提出有好几年了 不过我们始终没有
Versions of this idea have been around for a few years, but we haven’t had detectors
足够灵敏的探测器去测量当中微子穿过地球的不同部分时
sensitive enough to tell us how the number of extra neutrinos changes
多少额外的中微子发生了(形态上的)改变
when they travel through different parts of the Earth.
所以科学家们仔细的计算了探测器需要多精准
So these authors carefully calculated how sensitive a detector would need to be for
来完成如此精细的测量
this fine-grained measurement.
他们表示名为DUNE的探测器将在2027年开始运行
And they showed that a detector called DUNE, which should be operational in 2027,
最终它能够利用中微子探测地球内部结构
will finally be able to measure Earth’s internal structure using neutrinos.
所以在未来十年 我们可能会使用宇宙上最神奇的粒子
So within a decade, we might be using the universe’s ghostliest particles
来研究我们自己的小行星
to study our own little planet.
与此同时 其他的研究者正探索着
Meanwhile, other researchers are looking into
我们前所未见的一些最奇怪的星系
some of the strangest galaxies we’ve ever seen.
在这周的《自然》杂志上 一支天文学家团队发表了一项关于水母星系的研究
In this week’s Nature, a group of astronomers published a study on jellyfish galaxies, and
告诉我们为什么超大质量的黑洞突然开始增多
what they can teach us about why some supermassive black holes suddenly start feasting.
没错 水母星系是真实存在的
And yeah, jellyfish galaxies are a real thing!
各个星系以每小时成百上千公里的速度
Galaxies speed toward or away from the stuff around them
靠近或远离它们周围的物质
at hundreds of thousands of kilometers per hour.
当它们移动的时候 一些星系会撞上一种叫做星团内介质(ICM)的东西
But as they travel, some galaxies ram into what’s called the intracluster medium, or ICM:
大量气体和其他星系都没什么联系
Huge pockets of gas that aren’t connected to any particular galaxy.
当一个星系穿过星团内介质的时候 其中的气体会被拖到后面
And when a galaxy passes through the ICM, its own gas can get dragged behind
因为星系要推开星系内介质为自己开辟道路
as it tries to push the ICM out of the way.
这样星系后面就会形成长长的气体拖尾
This leaves long threads of gas and dust trailing behind the galaxy,
就像一个水母一样
making it look a lot like a jellyfish.
当这支队伍开始研究 一组水母星系的时候
When the team started studying a set of jellyfish galaxies,
他们注意到了 它与天文学上一个未解决的问题的联系
they noticed a connection to an unsolved problem in astronomy.
几乎所有的水母星系的中心都有着一个超大的活跃的黑洞
Almost all of the jellyfish galaxies had really active supermassive black holes at their centers
这些黑洞吞噬了许多气体和恒星
that were eating lots of gas and stars.
差不多所有星系的中心都有超大黑洞 不过通常
Just about all galaxies have supermassive black holes at their centers, but usually
它们不会吞噬太多 气体和恒星只是围绕着它们转
they’re not doing very much; gas and stars just orbit around them.
只有很偶然的情况下 大量气体和恒星会被黑洞吸进去
Very occasionally, though, huge quantities of gas and stars are sucked toward
它们或者直接被吸进去 或者被吸进去的同时释放大量的能量
the black hole, where they either fall in or get flung away with huge amounts of energy.
每当这时 天文学家们就认定这个星系或者黑洞是活跃的
When that happens, astronomers will say that the galaxy or black hole is active.
不过他们不确定一个由气体和恒星静静的围绕的黑洞是如何切换到
And they aren’t exactly sure what flips the switch from a black hole with gas and
一个活跃的吸收周围物质的黑洞这种形态的
stars quietly orbiting it to one with stuff actively diving into it.
事实表明 所有的水母星系往往都有一个活跃的黑洞
The fact that all these jellyfish galaxies also had active black holes was
这是一个有趣的关联 这个团队想要知道哪一个先生成
an interesting connection, and the team wanted to know which came first:
是活跃黑洞 还是水母触手?
the active black holes or the jellyfish tentacles?
如果在星系撞击星系内介质成为水母之前 黑洞就十分活跃
If the black holes were active before the galaxies hit the ICM and became jellyfish,
某些物质坠向黑洞然后可能会错过黑洞 然后被甩出
some of the material falling in toward the black holes might’ve missed and been flung
变成星系背后的拖尾 就形成了前所未有的
out into the trails behind the galaxy, making even bigger jellyfish
巨大水母星系
than would’ve otherwise been.
但如果在星系中的黑洞之前是平静的 (星系)与星团内介质的撞击就有可能
But if the galaxies’ black holes were quiet before, the collisions with the ICM might’ve
把一大团气体推入黑洞中心被吃掉 这样黑洞就变成了活跃的黑洞
pushed a whole bunch of gas into the center to get eaten up, making the black holes active.
通过测量星系的移动速度 以及星系在星团中的位置 作者们发现
By measuring the galaxies’ speeds and where they were in their cluster, the authors found
对于这些水母星系来说 与星系内介质的撞击 几乎必然是先发生的事情
that for these jellyfish, collisions with the ICM almost certainly came first
由此激活了黑洞
and activated the black holes.
几乎所有的水母星系穿过密度较大的星团内介质的时候速度都足够快 导致大量的
Almost all the jellyfish were moving quickly enough through the dense ICM that lots of
气体被被推向它们的中心
gas would’ve been pushed toward their centers.
并且 他们观测到一个不含活跃黑洞的星系
And the one galaxy they observed that didn’t have an active black hole was moving really
相比于其他星系来说 移动速度非常慢 并且它很可能没有足够的速度
slowly compared to the others, meaning that it probably wasn’t moving fast enough to
来把自己的气体推入中心(的黑洞)
have its gas pushed into the center.
天文学家们已经发现 星系合并或者其他大事件可以迫使气体
Astronomers already know that galaxy mergers and other large events can force gas toward
涌入星系中心的黑洞 并且激活它
a galaxy’s central black hole, activating it.
这篇新发表的论文表明 一些像穿过的零散的气团一样小的
But this new paper shows that something as minor as passing through a random pocket of
东西可以引爆星系 这也许可以解释
gas can set galaxies off, which might explain
那些活跃却没有水母触角的星系的成因
a bunch of active, non-jellyfish galaxies, too.
它们可能会猛烈撞击那些能把气体推进它们中心的东西 尽管
They might’ve slammed into something that pushed gas toward their centers, even if they
它们不再出来 (因此)以后也不形成像水母一样的外表
didn’t come out looking like jellyfish afterward.
所以有另一个去研究那些看起来最奇怪的星系的理由:
So that’s one more reason to study some of the weirdest-looking galaxies out there:
它们可以让我们懂得很多关于所有宇宙中正在发生的过程
they can teach us a lot about all kinds of processes happening in the universe.
如果你喜欢学习更多关于奇怪的星系的知识 你可以查看我们的视频
If you’d like to learn about some more weird galaxies, you can check out our video about
是有关天文学家们十分确定的3个不存在的星系
3 galaxies that astronomers are pretty sure shouldn’t exist.
结尾部分
[♪ OUTRO]

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视频概述

视频有两个主题:第一,利用中微子去探测地球内部结构;第二,水母星系的成因

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收集自网络

翻译译者

Dreaming

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审核团Z

视频来源

https://www.youtube.com/watch?v=FbzLXk18gU0

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