科学美国人60秒 SSS How to Find Loooong Gravitational Waves（在线收听）

How to Find Loooong Gravitational Waves

神秘的引力波

In 2016 the Laser Interferometer Gravitational-Wave Observatory, LIGO, made the first accepted detection of gravitational waves.

2016年激光干涉引力波天文台（即LIGO），首次进行了可被接受的引力波探测。

“So any time you move a mass it produces a gravitational wave…so black holes, like the ones LIGO detected, these are stellar mass black holes, about 10 times the mass of the sun. When they’re in orbit they’re accelerating constantly, so constantly producing gravitational waves.”

“事实上，每次你移动一个质量它都会产生引力波……所以就像LIGO检测到的那些黑洞一样，这些是恒星质量黑洞，大约是太阳质量的10倍左右。当它们在轨道上运行时，它们就会不断地加速，也就会不断地产生引力波。”

\Sarah Burke Spolaor, of the National Radio Astronomy Observatory in New Mexico, at the annual meeting of the American Association for the Advancement of Science in Boston on February 18th.

2月18日，美国新墨西哥州国家射电天文台的萨拉·伯克·斯波拉尔在波士顿召开的美国科学促进会年会上说道。

For gravitational waves produced by the acceleration of even bigger masses, we’re going to need what’s called the Laser Interferometer Space Antenna, or LISA.

对于由更大质量的加速度产生的引力波，我们将需要“激光干涉空间天线”（即LISA）。

“Now if you think of much bigger masses, something like a million times the mass of the sun, these things are moving much more slowly, much more far apart, and they’re producing lower frequency gravitational waves. And this is what LISA can detect. So LIGO, which is operating at these very fast orbits, fast frequencies, is unable to detect these things that are moving much more slowly and are on a much bigger scale.”

“如果你现在想象一种更大的质量，一种比太阳质量大百万倍的质量，它们移动得要慢很多，相互距离得要更远，并且在不断产生低频引力波。这就是LISA能探测到的引力波。而LIGO则在非常快、频率非常高的轨道上运行，所以它无法探测到这些移动得更慢、且移动范围更广的物质。”

And for even bigger masses, you get to what Burke Spolaor is working on: Pulsar Timing Arrays.

然而对于更大的质量，你就需要了解伯克·斯伯拉尔所做的工作了：脉冲星计时阵列。

“What we do with this technique is use radio telescopes to observe pulsars, which are neutron stars that are rotating very rapidly and sending their beams of emission across Earth, several hundred times per second…and the idea is of course if a gravitational wave is passing through Earth, the gravitational wave is stretching and squeezing our space time. And the tick that we see from these very, very regularly spinning pulsars is speeding up and slowing down.

“我们通过这项技术利用电波望远镜来观察脉冲星——一种旋转非常迅速、以每秒几百次的频率向地球发射光束的中子星……自然我们的想法就是，如果引力波穿过了地球，那么它也在拉伸和挤压我们的时空。而我们从这些非常非常规律的旋转脉冲星上看到的计时速率也在进行加速和减速。

“Just like we can scale the stellar mass black holes that LIGO can detect, to very, very intermediate mass very large black holes that LISA can detect, Pulsar Timing Arrays will probe the very massive end of this distribution and the most massive, so the billion to even 10 billion solar mass binary black holes in the universe. So every time you get a galaxy merger you can get a binary supermassive black hole, which then will contribute signal to our Pulsar Timing Arrays by propagating through the galaxy.

“就像我们可以测量LIGO检测到的恒星质量黑洞，以及LISA能够检测到的质量中级、非常非常大的黑洞一样，脉冲星计时阵列可以探查宇宙中分布范围非常广、规模非常大——是太阳质量10亿倍甚至百亿倍的双黑洞。每次星系合并，都会产生一个特大质量的双黑洞，而它会通过星系传播，向我们的脉冲星计时阵列提供信号。”

“Of course, gravitational waves does not stop at detection. What we really want to do is astrophysics with gravitational waves. And use it as a new tool to observe the universe and understand our place in it.”

“当然，引力波不会止于探测。我们真正想做的是用引力波研究天体物理学。用它作为观察宇宙和理解我们所处位置的一种新工具。”