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第10期:我们如何知道黑洞的存在

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If you've heard only one thing about black holes, it's probably that, once inside a black hole's event horizon, nothing, not even light, can escape.

如果你只听说过一件关于黑洞的事,可能就是,一旦进入黑洞的视界,任何东西,甚至光,都无法逃脱。
At which point it's natural to wonder, if nothing can escape a black hole, how could we ever observe them?
在这种情况下,我们很自然地会想,如果没有任何东西可以逃脱黑洞,我们怎么可能发现它们呢?
How do we even know they exist?
我们怎么知道它们的存在呢?
Well, only things inside the event horizon are stuck – black holes also gravitationally pull on stuff outside their event horizons,
被困住的只有视界内的事物—黑洞也会对视界外的物体产生引力
and by looking at that stuff we can get a really good sense that there's a black hole nearby.
并且通过观察这些事物,我们可以很好地感觉到附近有一个黑洞。
For example, lots and lots of stars orbit in pairs , but we also see stars orbiting things that aren't normal stars,
例如,很多很多恒星都是成对运行的,但我们也看到恒星绕着非普通恒星运行,
but instead emit crazy amounts of x-rays – and x-rays in space often come from dust and gas
它们会释放大量的x射线,而太空中的x射线通常来自于尘埃和气体,
that gets superheated while spiraling into a very dense, very heavy object.
当这些气体和尘埃在旋转成密度非常大、质量非常大的物体时,它们会变得过热。
Anyway, by figuring out the mass and orbital characteristics of the stars whose partners emit x-rays, we can determine how heavy the partners are.
不论如何,通过计算恒星(它们的伴星会发射x射线)的质量和轨道特征,我们可以确定伴星的重量。
Some parters are lightweight enough to be neutron stars, but neutron stars can only get so big before they collapse in on themselves
一些伴星很轻,足以成为中子星,但中子星只有在坍塌之前才能变成这么大
– theoretical calculations put their upper size limit at around 2-3 times the mass of the sun,
根据理论计算,它们的上限是太阳质量的2到3倍左右,
and the biggest ones we've observed all fall inside that limit.
并且我们观察到的最大的中子星也在这个范围内。
And yet, there are plenty of stars whose orbits clearly show that their x-ray-emitting partners are 5-10 times the mass of the sun,
然而,有很多恒星的轨道清楚地表明,它们发射x射线的伴星的质量是太阳的5到10倍,

第10期:我们如何知道黑洞的存在.jpg

and we simply don't know anything else these could be other than black holes.

并且除了黑洞,我们真的不知道还有其他的解释。
Sometimes you don't even need an orbiting star at all, and just the x-rays and radio waves from the hot infalling material
有时候,我们甚至根本不需要轨道上的恒星,仅需要x射线以及来自热陨落物质的电波
can be used to determine the mass of a solitary non-star object.
就可以确定一个孤立的非恒星物体的质量。
In some cases they turn out to be neutron stars, but in others they turn out to be way too heavy, and can only be black holes.
在一些情况下,它们其实是中子星,但其他情况下,它们其实非常重,而且只可能是黑洞。
There are also objects at the centers of lots of galaxies (including our own), that emit lots of x-rays, radio waves and infrared radiation,
在很多星系(包括地球)中的物体都会发射大量x射线、电波和红外线照射,
but not much visible light, and we know these objects are stupendously heavy because of the way that nearby stars and hot glowing dust orbit them.
但可见光不多,并且我们知道由于附近恒星和热的发光尘埃围绕它们的方式,这些物体非常的重。
These orbits tell us the objects are both so heavy and so small they can't possibly be a star or cluster of stars or distributed clumps of other invisible matter;
这些轨道告诉我们这些物体即重又小,它们不能是恒星或星团或不可见物质的分布团;
the only thing they could be is supermassive black holes. For example, in the middle of the Milky Way there's an x-ray,
它们只有可能是特大质量的黑洞。例如,在银河中间,有一条x射线、
radio wave and infrared-emitting object called "Sagittarius A" with nearby stars orbiting it in such such small, fast orbits
电波和红外线发光的物体—“人马座A”,附近的恒星以如此小而快速的轨道环绕它
that we know it weighs 4 million times as much as the sun! And finally, we've also directly observed,
我们知道它的重量是太阳的400万倍!最终,我们还直接观察到,
on multiple occasions, gravitational waves that were emitted from the inspiralling collisions of two very heavy dense objects.
在很多情况下,引力波是由两个非常重的密度物体的旋进碰撞发出的。
Some of those waves have the signature of a collision between objects lightweight enough to be neutron stars.
其中一些波具有物体间碰撞的特征,这些物体轻到足以成为中子星。
But other waves could only have come from collisions between objects far too heavy to be anything
但其他波只可能来自物体之间的碰撞,这些物体太重了,
but pairs of black holes merging to become single, bigger, black holes.
所以只能是一对黑洞合并成一个更大的黑洞。
And in these cases, the details of the wave signatures looked exactly like what theoretical black hole collision calculations predict.
在这些情况下,波信号的细节与理论黑洞碰撞计算预测的完全一致。
So, in many different places throughout the universe, we've detected very dense high-mass objects by their gravity –
所以在宇宙很多不同的地方,我们通过它们的重力探测到密度非常大的物体—
either indirectly via their affect on nearby bright stuff like stars or accretion disks of gas and dust, or directly via their gravitational waves.
或者通过它们对附近的明亮物质,如恒星或气体和尘埃吸积盘的影响间接地,或者直接通过它们的引力波。
Many of these dense high-mass things are too dark to be regular stars,
很多高密度的物体都太暗了,不能是普通恒星;
too compact AND too dark to be clusters of stars, and too heavy to be neutron stars.
也太致密太黑了,所以不能是星团;太重了,不可能是中子星。
They exist, they behave pretty much exactly the way physics predicts black holes would act,
它们确实存在,它们的行为和物理学预测黑洞的行为几乎完全一样,
and there's literally nothing else they could be.
而且它们确实不可能是别的东西。
To quote an astronomer: we have "strong confidence that black holes,
引用一位天文学家的话说:“我们坚信黑洞,
or at least objects that have many of the features of black holes, exist"
或者至少是具有黑洞许多特征的物体,是存在的。”
In other words, if it looks like a black hole and acts like a black hole… we call it a black hole.
换言之,如果它看起来像黑洞,表现也像黑洞......我们就称之为黑洞。

重点单词   查看全部解释    
predict [pri'dikt]

想一想再看

v. 预知,预言,预报,预测

联想记忆
collapse [kə'læps]

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n. 崩溃,倒塌,暴跌
v. 倒塌,崩溃,瓦解

联想记忆
universe ['ju:nivə:s]

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n. 宇宙,万物,世界

联想记忆
emit [i'mit]

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vt. 发出,放射,吐露

联想记忆
confidence ['kɔnfidəns]

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adj. 骗得信任的
n. 信任,信心,把握

联想记忆
quote [kwəut]

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n. 引用
v. 引述,举证,报价

联想记忆
escape [is'keip]

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v. 逃跑,逃脱,避开
n. 逃跑,逃脱,(逃

 
multiple ['mʌltipl]

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adj. 许多,多种多样的
n. 倍数,并联

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affect [ə'fekt]

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vt. 影响,作用,感动

联想记忆
gravity ['græviti]

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n. 重力,严重,庄重,严肃

联想记忆

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