就在今天，2018年3月14日，英国著名物理学家史蒂芬 霍金逝世，享年76岁。

他于1942年1月8日出生于英国牛津，是英国剑桥大学著名物理学家，也是现代最伟大的天文学、物理学家之一。

霍金的主要研究领域是宇宙论和黑洞，证明了广义相对论的奇性定理和黑洞面积定理，提出了黑洞蒸发现象和无边界的霍金宇宙模型。在统一20世纪物理学的两大基础理论——爱因斯坦创立的相对论和普朗克创立的量子力学方面走出了重要一步。

1963年，21岁的他不幸被诊断患有肌肉萎缩性侧索硬化症即运动神经细胞病。当时，医生曾诊断身患绝症的他只能活两年，可他一直坚强地活了下来。从此之后，他全身瘫痪，不能言语，手部只有三根手指可以活动。但这丝毫不影响他在物理学以及天文学领域对人类做出的巨大贡献。

大家对于霍金应该都不陌生，他的很多理论都是我们熟知的，有些更是出现在我们的教科书上。而且，霍金作为当代理论物理的代言人，对于在公众面前宣传理论物理作用是极大的，这一影响力应该无人能出其右。至少对于小编自己来讲，霍金的物理科普书籍给了我很大的启发和影响，小编对于天文和物理的兴趣都源自他的科普书籍《时间简史》。简单易懂，却又准确阐释宇宙未来之变，探索着宇宙的起源。用最通俗的语言解释宇宙的原理，把我们这些对于高深理论物理一窍不通的普通人带到了理论物理的最前沿。

在这里，小编给大家推荐一些关于霍金的电影，或者霍金编写的科普书籍。

另外，对于备考PTE的同学，小编也帮大家总结了一些宇宙和物理相关的词汇，这些词汇都是PTE考试可能涉及的，大家要认真记啦~

T-Mate小编今天再给大家分享一篇关于宇宙的PTE retell lecture真题原文，大家可以熟悉下。

Galaxy Darkness

Our friends at the Highlands Museum and Discovery Center in Ashland, Kentucky, asked a very good question. Why is it dark in space?

That question is not as simple as it may sound. You might think that space appears dark at night because that is when our side of Earth faces away from the Sun as our planet rotates on its axis every 24 hour. But what about all those other far away suns that appear as stars in the night sky? Our own Milky Way galaxy contains over 200 billion stars, and the entire universe probably contains over 100 billion galaxies. You might suppose that many stars would light u the night like daytime.

Until the 20th century, astronomers didn't think it was even possible to count all the stars in the universe. They thought the universe went on forever. In other words, they thought the universe was infinite.

Besides being very hard to imagine, the trouble with an infinite universe is that no matter where you look in the night sky, you should see a star. Star should overlap each other in the sky like tree trunks in the middle of a very thick forest. But, if this were the case, the sky would be blazing with light. The problem greatly troubled astronomers and became known as Olbers paradox. A paradox is a statement that seems to disagree with itself.

To try to explain the paradox, some 19th century scientists thought that dust clouds between the stars must be absorbing a lot of the starlight so it wouldn't shine through to us. But later scientists realized that the dust itself would absorb so much energy from the starlight that eventually it would glow as hot and bright as the stars themselves.

Astronomers now realize that the universe is not infinite. A finite universe --- that is, a universe of limited size --- even one with trillions and trillions of stars, just wouldn't have enough stars to light up all of space.

Although the idea of a finite universe explains why Earths sky is dark at night, other causes work to make it even darker. 

最后，再给大家分享一些霍金的名言，希望这位教会普通人仰望星空，并为人类做出了巨大贡献的伟大物理学家能够被永远铭记。R.I.P

Titan老师是谁？他是悉尼第一位PTE华人老师，口语满分的他最擅长在短时间内帮助学生掌握PTE解题思路，攻破65/79分大关。点击关注T-mate官方微信或添加小助手微信，了解最新考试咨询和课程优惠信息！

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