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黑洞 What is a black hole? Well, it's difficult to answer this question, since the terms we would normally use to describe a scientific phenomenon are inadequate here. Astronomers and scientists think that a black hole is a region of space (not a thing) into which matter has fallen and from which nothing can escape - not even light. So we can't see a black hole. A black hole exerts a strong gravitational pull and yet it has no matter. It is only space - or so we think. How can this happen? 什么是黑洞呢？这个问题很难回答，因为我们通常用来描述一种科学现象的术语用在这里来解释是不够的。天文学家和科学家们认为黑洞是个空间区域，物体会掉进去，而没有物体能从中逃逸出来――即使是光也不能，所以我们看不到黑洞。黑洞产生很强的引力，而它却没有物质。它只是空间――或者我们认为是空间。这是怎样发生的呢？ The theory is that some stars explode when their density increases to a particular point; they collapse and sometimes a supernova occurs. From earth, a supernova looks like a very bright light in the sky which shines even in the daytime. Supernovae were reported by astronomers in the seventeenth and eighteenth centuries. Some people think that the Star of Bethlehem could have been a supernova. The collapse of a star may produce a White Dwarf or neutron star - a star, whose matter is so dense that it continually shrinks by the force of its own gravity. But if the star is very large (much bigger than our sun) this process of shrinking may be so intense that a black hole results. Imagine the earth reduced to the size of a marble, but still having the same mass and a stronger gravitational pull, and you have some idea of the force of a black hole. Any matter near the black hole is sucked in. It is impossible to say what happens inside a black hole. Scientists have called the boundary area around the hole the "event horizon." We know nothing about events which happen once objects pass this boundary. But in theory, matter must behave very differently inside the hole. 理论是一些星球的密度增长到特定的时刻就会爆炸。它们崩溃时会产生超新星。在地球上看去，超新星就像天空中非常耀眼的灯，即使在白天也能看到其闪光。在17、18世纪，天文学家就有关于超新星的记录，一些人认为圣诞星可能是一颗超新星。一颗星崩溃可能产生吸引力，你就了解黑洞的力量。黑洞附近任何物质都会被吸进去，根本不可能说出黑洞里面发生了什么。科学家们把这个洞的边缘区域称为"事界"。一旦物体经过这个边界，我们对所发生的事一无所知。但是在理论上，在黑洞里的物质的运动肯定与洞外有很大区别。 For example, if a man fell into a black hole, he would think that he reached the center of it very quickly. However an observer at the event horizon would think that the man never reached the center at all. Our space and time laws don't seem to apply to objects in the area of a black hole. Einstein's relativity theory is the only one which can explain such phenomena. Einstein claimed that matter and energy are interchangeable, so that there is no "absolute" time and space. There are no constants at all, and measurements of time and space depend on the position of the observer. They are relative. We do not yet fully understand the implications of the relativity theory; but it is interesting that Einstein's theory provided a basis for the idea of black holes before astronomers started to find some evidence for their existence. It is only recently that astronomers have begun specific research into black hole. In august 1977, a satellite was launched to gather data about the 10 million black holes which are thought to be in the Milky Way. And astronomers are planning a new observatory to study the individual exploding stars believed to be black holes. 例如：如果一个人掉进黑洞，他会认为自己很快就达到了其核心，但在"事界"的观察者则认为这个人根本不会到达黑洞的核心。我们的时空规律看起来不适于黑洞里的物体。爱因斯坦的相对论是唯一可以解释这种现象的理论。爱因斯坦声称物质和能量是可以互相转化的，因此就没有绝对的时间和空间，根本不存在永恒，时间和空间的衡量取决于观测者所在的位置，它们是相对的。我们还没有完全理解相对论的含义，但有意思的是，在天文学家的着手发现黑洞的存在证据之前，爱因斯坦就提供了黑洞这种想法的基础。只是近来科学家才开始对黑洞的具体研究。1977年8月，发射了一颗卫星去收集关于被认为是在银河系的一千万个黑洞的数据。天文学家正在计划一个新的天文台以研究个别的正在爆炸的被相信要变为黑洞的星球。 The most convincing evidence of black holes comes from research into binary star systems. Binary stars, as their name suggests, are twin stars whose position in space affects each other. In some binary systems, astronomers have shown that there is an invisible companion star, a "partner" to the one which we can see in the sky. Matter from the one which we can see is being pulled towards the companion star. Could this invisible star, which exerts such a great force, be a black hole? Astronomers have evidence of a few other stars too, which might have black holes as companions. 黑洞最有说服力的证据来自对双星系的研究。双星，正如它们的名字所表明的，是两颗在空间位置上互相影响的星球。在一些双星系里，天文学家已经表示这里有一颗看不到的伴星，即我们可以在天空中看到的一颗星球的伙伴。来自我们的看到的星球的物质正被吸引到伴星去。这颗产生如此巨大力量的看不见的星球会是黑洞吗？天文学家还有其他一些星球的证据，这些星球可能与黑洞相伴。 
对黑洞的研究刚刚开始，各种推测会层出不穷。在我们银河系的中心很可能存在着一个巨大的黑洞正以极快的速度吞食着星球。人类有一天也会面临被吞食的命运。而科学家提出，有一天高科技利用轩洞的能量为人类服务。这些设想听起来像科幻小说，但空间中黑洞的理论被许多严谨的科学家和天文学家接受。他们向我们展示了一个以完全不同于我们理解的方式运行的世界，并对我们最基本的时空经验提出了疑问。 Worlds within Worlds 世界中的世界 First of all let us consider the earth (that is to say, the world) as a planet revolving round the sun. The earth is one of mine planets which move in orbit round the sun. These nine planets, together with the sun, make up what is called our solar system. How this wonderful system started and what kept it working with such wonderful accuracy is largely a mystery but astronomers tell us that it is only one of millions of similar systems is space, and one of the smallest. 首先让我们把地球看作是围绕太阳运行的一颗行星。地球是沿轨道围绕太阳运行的九大行星之一。这九大行星和太阳一起组成了所谓的我们的太阳系。这个奇妙的星系是怎样开始的，什么使它保持精确地运行，这是一个很大的迷。但是天文学家告诉我们太阳系只是太空里几百万个相似的星系中的一个而且是最小的一个。 The stars which we see glittering in the sky on a dark and cloudless night are almost certainly the suns of other solar systems more or less like our own, but they are so far away in space that it is unlikely that we shall ever get to know very much about them. About our own solar system, however, we are learning more every day. 在漆黑的夜空，我们看到的闪烁的星星几乎肯定是其他太阳系中有些类似我们星系中的恒星。但是它们在太空中距离我们如此遥远以至于我们不可能对其了解太多。然而对于我们的太阳系，每天我们都会了解到更多东西。 Before the American and Russian astronauts made their thrilling journeys into outer space it was difficult for us to realise what our earth looked like from hundreds of thousands of miles away, but the photographs which the astronauts were able to take show us the earth in space looking not very different from what the moon looks like when we look at it from the earth. The earth is, however, very different from the moon, which the American astronauts have found to be without life or vegetation, whereas our earth is very much alive in every respect. The moon, by the way , is called a satellite because it goes round our earth as well as round the sun. In other words, it goes round the sun with our earth. 在美国和俄罗斯宇航员进行激动人心的太空旅行之前，我们很难认识到从数十万英里以外的地方看地球会是什么样子。但是宇航员们能够拍到的照片为我们展示出在太空中地球看上去和我们在地球上看到的月亮没有什么大的不同。然而，地球和月亮确有很大不同，这就是美国宇航员所发现的月球上没有生命和植物。而我们地球的各个地方都有生机。顺便说一下，月亮被称为卫星，是因为它围绕着我们地地球盍同时围绕太阳运转。换句话说，随着地球围绕太阳运行。 
我们地球表面覆盖着一块块的陆地和更大面积的水域。让我们首先考虑一下水域，其总面积大约是陆地面积的三倍。很大的隔开的水域称为"洋"，小一些的水域称为"海"。 In most of the oceans and seas some of the water is found to be flowing in a particular direction - that is to say, from one part towards another part of the ocean or sea concerned. The water which is flowing in this manner is said to be moving as a "current." There are many thousands of currents in the waters of the oceans and seas, but only certain of the stronger and better marked currents are specially named and or great importance. These currents are important because they affect the climate of the land areas close to where they flow and also because they carry large quantities of microscopic animal and vegetable life which forms a large part of the food for fishes. 在大部分海洋里，人们发现一些水是沿着特有的方向流动---这就是说，从海洋的一个区域流向另一区域以这种方式流动的水叫做"海流"。在海洋的水域里有成千上万条海流，但只有几条较强和较显著的海流被专门命名。这些海流的重要，是因为它们影响着流经水域的陆地的气候，并携带大量的微生物、植物，而这些却是鱼类的大部分食品。 The nature and characteristics of the surface of the land areas of the earth vary a great deal from area to area and from place to place. The surface of some areas consists largely of high mountains and deep valleys whilst, in other areas, most of the surface consists of plains. If one made a journey over the Continents one would find every kind of surface including mountain ranges, plains, plateaux, deserts, tropical forestlands and empty areas covered permanently by ice and snow. 地球不同区域的陆地表面自然特征区别很大。一些区域的地表由大量的高山和深谷组成，而其他区域，大部分地表却由平原组成。如果一个人做一次大陆旅行，他会发现各种各样的地貌，包括山区、平原、高原、沙漠、热带雨林和永久性冰雪覆盖的空旷无人区。 When thinking and learning about the world we should not forget that our world is the home of a very great many different people - peoples with different coloured skins, living very different lives and having very different ideas about a great many important things such as religion, government, education and social behaviour. 当我们想象和了解这个世界时，我们不应忘记我们的世界是许多不同种类人居住的家园--他们有不同的肤色，过着极不相同的生活，对诸如宗教、政府、教育和社交行为等许多重要事情持有极为不同的观点。 The circumstances under which different people live make a great difference between the way in which they live and the way in which we live, and it ought to be our business to try to understand those different circumstances so that we can better understand people of other lands. Above all, we should avoid deciding what we think about people different from ourselves without first having learned a great deal about them and the kind of lives they have to live. It is true to say that the more we learn about other people, the better we understand their ideas and, as a rule, the better we like those people themselves. 不同民族的生活环境造就了他们和我们极为不同的生活方式，我们应该做的是努力了解他们不同的生活环境以便更好地理解其他地区的人们。在没有对他们及他们必须过的那种生活有相当多的认识前，我们应当避免对他们有先入为主的看法。确实我们了解别人越多，我们越能理解他们的观点，通常我们就会更喜欢那些人。
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