墨尔本PTE素材库——Twin Birth Proposed for Colliding Black Holes That Produced Gravitational Waves

墨尔本PTE素材库——Twin Birth Proposed for Colliding Black Holes That Produced Gravitational Waves

中文批注

几个月前，通过天文望远镜，科学家们发现，有两个黑洞对撞着出现，据观察，这两个黑洞是从同一颗恒星产生。具体是怎么回事呢？听完这段音频的同学们能否回答呢？要知道，这篇文章的题材是PTE考试比较喜欢的天文物理方面的内容~同学们，可以试着做做retell the lecture的练习哦！

澳大利亚语言学院会定期整理一些PTE的素材库，让各位PTE的考生，能够在平时练习的时候就能接触到一些和official questions criteria相近的话题素材，不但能够锻炼PTE考生的听力和复述的能力，也能在消化每篇素材的过程中提高自己的阅读能力以及词汇量。

【Key vocabulary】

Gravitational adj. 重力的

Gravitational wave 重力波

Ripple n. 波纹的

Colliding adj. 对撞的

Collision n. 冲突，抵触

Full Transcript

A flash of light shortly after the detection of gravitational waves could mean that that historic event has an added wrinkle—the black holes that collided may have been born in the same collapsing massive star.   

The news last month that gravitational waves had been discovered made waves throughout the world of science. The finding, from the Laser Interferometer Gravitational-Wave Observatory, or LIGO, showed that extreme gravity can cause ripples in spacetime. In the case studied, the extreme gravity came from two colliding black holes. Now one scientist is suggesting an added wrinkle—that those two black holes might have originated in a single star.

“The situation is similar to a pregnant woman that has twin babies in her belly.” Avi Loeb of the Harvard-Smithsonian Center for Astrophysics. He’s proposing the idea in a paper that’s been accepted for publication in the Astrophysical Journal Letters. [Abraham Loeb, Electromagnetic Counterparts to Black Hole Mergers Detected by LIGO]

Loeb became suspicious because just 0.4 seconds after LIGO spotted the gravitational waves, a space telescope called Fermi glimpsed a bright flash of gamma-ray light in the same area of the sky.

“Detecting such a signal is quite surprising from a collision of two black holes. What could be the source of a flash of light following a black hole merger?”

Colliding black holes should not produce such light—but the death of a very massive star could.

“My idea was that if the star is spinning very rapidly to start with, then as its core collapses it produces a bar that breaks into two clumps of matter, sort of like a dumbbell configuration. And these two clumps of matter orbit a common center, and they eventually collapse independently into two black holes.”

Of course, it’s possible that the Fermi telescope signal was a false alarm. So we’ll see if future gravitational wave detections are also accompanied by flashes of light—supporting the idea that twin black holes collided upon the collapse of a massive star.

—Clara Moskowitz

(source: http://www.scientificamerican.com/podcast/episode/twin-birth-proposed-for-colliding-black-holes-that-produced-gravitational-waves/)