Black holes are some of the strangest and most fascinating objects in space.
黑洞是太空中最不可思议和最迷人的物质之一。
They're extremely dense, with such strong gravitational fields, that not even light can escape their grasp.
黑洞的密度极高，引力场极强，连光都无法从其视界逃脱。
Because nothing can escape a black hole, they are invisible, making them very difficult to find.
因为没有任何物质可以逃脱黑洞，它们是不可见的，所以黑洞很难被观测到。
However, by using special telescopes we have detected them, by studying the influence they have on their surroundings.
然而，通过使用特殊的望远镜，研究黑洞对周围区域的影响，我们发现了它们。
But what some of you may be surprised to find out, is that we can also listen to these elusive cosmic monsters, and NASA has recently released the audio of a supermassive black hole located 250 million light-years away.
但你们中的一些人可能会惊讶地发现，我们也可以听到这些神秘的太空怪物的声音，美国宇航局最近公布了一个2.5亿光年之外的超大质量黑洞的录音。
Now I know that many of you will be thinking "if space is a vacuum, then sound cannot travel through it".
现在我知道你们中的许多人会想“如果太空是真空，那么声音就无法通过太空传播。”
But it turns out that this is a popular misconception.
但事实证明，这是一个流行的误解。
Although most of space is essentially a vacuum providing no medium for sound waves to propagate through, a Galaxy cluster, on the other hand, has ample amounts of gas drifting between the hundreds or even thousands of galaxies within it.
虽然太空的大部分本质上是真空，没有提供介质让声波传播，但另一方面，一个星系团拥有大量气体在其内部数百甚至数千个星系之间漂移。
This means that sound waves emanating from a supermassive black hole can travel many light years through this thin surrounding medium.
这意味着从超大质量黑洞发出的声波可以通过周围这种薄薄的介质传播数光年。
The audio recording you are about to hear was created after astronomers in 2003 discovered that sound waves sent out by a supermassive black hole caused ripples through the hot gas at the centre of the Perseus galaxy cluster, which is located 250 million lightyears away.
2003年天文学家发现超大质量黑洞发出的声波在距离2.5亿光年外的英仙座星系团中心的高温气体中引起波动，下面你即将听到的录音就是在这之后创建的。
These sound waves were recorded by NASA's Chandra X-ray observatory, but cannot be heard by humans, the pitch is well below the limits of our hearing.
这些声波是由美国宇航局的Chandra X-ray射线天文台记录的，但人类听不到，因为其音高远低于我们的听觉极限。
But, for the first time, astronomers have extracted these sound waves and made them audible.
但是，天文学家第一次提取了这些声波，并使它们能被人类听见。
The sound waves were extracted in radial directions, as you will see in the animation that comes with the recording.
声波沿半径方向提取，正如你将在录音附带的动画中看到的那样。
The signals were then resynthesized into the range of human hearing by scaling them upward by 57 and 58 octaves above their true pitch.
然后将这些信号的音高上调57和58个八度，重新合成到人类的听觉范围内。
Another way to put it is that they are being heard 144 quadrillion and 288 quadrillion times higher than their original frequency.
另一种说法是，它们被听到的频率比它们原来的频率高144万亿和288万亿亿倍。
The result is this eerie, intergalactic howl.
结果出来的就是这种在星系间的怪异嚎叫。
This is the sound of a distant, supermassive black hole ringing throughout the universe.
这是一个遥远的超大质量黑洞在太空中回响的声音。
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