墨尔本PTE素材库——Model Black Hole Re-Creates Stephen Hawking Prediction

墨尔本PTE素材库——Model Black Hole Re-Creates Stephen Hawking Prediction

中文批注

这段音频主要说了通过模拟黑洞的吞噬方式，霍金的猜想被证实。

大家都知道，科学类一直都是PTE考试的重点内容，这篇文章，略有难度，单词量也有一些，适合基础比较好的同学，作为一篇拓展练习和词汇积累的听力阅读材料。

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。例如这篇关于黑洞实验的文章，大家可以试着re-tell这段视频的内容，并回答以下几个问题：

霍金的猜想具体是什么？

为什么声音也会被吸进黑洞里面呢？

答不出来的同学可是要加油啦~

【key vocabulary】

Analogue n. 类似物

Theoretical physicist 理论物理

The event horizon 黑洞表面

Quantum effect 量子效应

Photons n. 光子

Sweep back 往后掠

Entanglement n. 缠绕

Paradox n. 悖论

Full Transcript

A black hole analogue, which traps sound instead of light, generates “Hawking radiation,” a key prediction by the theoretical physicist. Christopher Intagliata reports.

Black holes got their name because light can’t escape them, beyond a certain radius—the event horizon. But in 1974 Stephen Hawking proposed that quantum effects at the event horizon might cause black holes to be…not completely black.

“Hawking said that pairs of particles should be created at the event horizon.” Jeff Steinhauer, a physicist at the Israel Institute of Technology. “One particle exits the black hole and travels away, perhaps to Earth, and the other particle falls into the black hole.”

Ideally, we could just study those exiting particles…which make up the so-called Hawking radiation. But that signal is too weak. We can’t see it against the universe’s background radiation. So Steinhauer built a model of a black hole instead. Which traps not photons, but phonons—think of them as sound particles—using a gas of rubidium atoms, flowing faster than the speed of sound.

“And that means that phonons, particles of sound, trying to travel against the flow are not able to go forward. They get swept back by the flow. It’s like someone trying to swim against a river which is flowing faster than they can swim. And the phonon trying to go against the flow is analogous to a photon trying to escape a black hole.”

Steinhauer doesn’t actually pipe sound particles into the device. He doesn’t need to. He merely created the conditions under which quantum effects predict their appearance. “So the two swimmers can come into existence simultaneously without anybody supplying energy to create them.”

He ran the test 4,600 times—the equivalent of six days—and took pictures of the results. And indeed, he saw a correlation between particles emanating into and out of the model black hole…an experimental demonstration of Hawking radiation. The results appear in Nature Physics. [Jeff Steinhauer, Observation of quantum Hawking radiation and its entanglement in an analogue black hole]

Steinhauer also determined that the partner particles had a quantum connection, called entanglement…which could help theorists investigating the information paradox. “So there’s the question of where does information go, if one throws it into a black hole?” This study can’t answer that. But, he says, “it helps give hints, to direct physicists towards the new laws of physics, whatever they might be.”

(source: http://www.scientificamerican.com/podcast/episode/model-black-hole-re-creates-stephen-hawking-prediction/)