Explain and expand. • The investigators are handicapped by a shortage of evidence.• The investigators are handicapped by a shortage of evidence. • If a "clock" could be found, it would be possible to obtain evidence about the earth's rotation and the factors affecting it. • Corals may not be alone in this field. Text 7 THE FUTURE OF THE EARTH What does modern science have to say about the future development and fate of the earth? Any prediction, of course, can be no more than a speculation. Astrophysicists who have been studying the development and the life cycles of typical stars have accumulated enough information to make trustworthy predictions about the future of the sun. At some time in the future the hydrogen supply of the sun will begin to run low. It might be concluded that this will cause a slow but steady decrease of the intensity of solar radiation. However, this will not be the case. Paradoxically, a star increases its emission of light when its hydrogen supply is being reduced. The sun in the far distant future will not become hotter, but will substantially expand. It is not difficult to imagine what will happen when the increasing solar radiation gradually affects the earth. First, the oceans will evaporate; the water vapour, together with the atmosphere, will escape into space. Then, the temperature of the surface will rise until the surface materials again assume the liquid state. Life on earth will have terminated by that time. The next step in the development of the sun will occur suddenly, within a few days or weeks, the sun will change into a completely different type of star, a white dwarf. It will be a sphere no bigger than the earth, with almost the same mass. The sun will still be able to hold all its planets in their orbits. In fact, the planets, including the earth, will survive this cosmic catastrophe without any significant change in their orbital parameters. As the sun is transformed from a red giant into a white dwarf, its total luminosity will again decrease
These thought have stimulated a great deal of speculation. It is not impossible that at that time a second act in the history of life on earth will start anew. When the solar radiation on earth has gradually been reduced, the Earth's crust will resolidify, and volcanic activity will persist sufficiently to give our planet a new atmosphere — and even a new ocean. The new atmosphere and the new ocean may have a lifetime of several billion years. So, there will be a chance for life to develop. Thus the fantastic story of life on Earth might repeat itself. All these events, if they occur at all, are mostly of academic interest only. They will not directly influence the fate of mankind. Mere is, however, the chance that, in the less distant future, other events and changes of earth will threaten mankind — for instance, natural catastrophes, such as floods or earthquakes. They occurred in the past, and they will surely occur in the future. Earthquakes and volcanic activity are closely related. Volcanic eruptions have been of great significance during the geological evolution of the earth. There would otherwise be no oceans. Earthquakes, therefore, should be considered as a necessary evil, as they are among the geophysical processes that the earth will never be without. Still other phenomena on the earth's surface cause catastrophes, though of less immediate danger because they arise from gradual processes. It is known, for example, that the level of the sea has been rising slowly ever since the end of the last ice age. The reason for this rise is that much of the ice that covered large areas on the earth a hundred thousand years ago has melted, and the melt water has caused the oceans to spill over. This will go on for the next fifty thousand years; as a result, the level of the oceans will rise by another hundred, two hundred, or even three hundred feet. A new ice age would be another catastrophe of the slow kind. This could occur during the next fifty thousand to one hundred thousand years. It would prevent the further rise of the sea level but it would cause a sharp worsening of the climate all over the earth. In fact, an extensive glaciation of the planet would cause considerable lowering of the sea level, which in turn would uncover millions of square miles of new land in nonglaciated areas. These drastic changes would not have catastrophic consequences because mankind would have thousands of years to adapt to them. Ш Give the Russian for: Trustworthy predictions; to run low; this is not the case; it is not difficult to imagine that...; to assume the liquid state; within a few days; a great deal of speculation; to be of academic interest; to be of great significance ■ Give the English for: предсказания; накапливать информацию; делать предположения; когда-нибудь в будущем; можно ли сделать вывод, что...; уменьшать; увеличивать; сокращать; расширять(ся); подниматься; высвобождаться; в самом деле; вполне возможно, что...; начаться заново; угрожать человечеству; вызывать катастрофы; в результате; ухудшение климата; понижение уровня моря; однако; следовательно; в противном случае
• The level of the sea has been rising ever since the end of the last ice 1 age. i • The meet water has caused the oceans to spill over. • What does sciences have to say about..:? • Mankind will have thousands of years to adapt to drastic changes, j • A new ice age would be another catastrophe. • There would otherwise be no oceans. • As the sun is transformed..., its total luminosity will again decrease.
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substantially. It is quite possible that the sun will then continue to shine for some further billions of years, with a brightness much like the present.
