Any physical theory is always provisional, in the sense that it is only a hypothesis; you can never prove it. No matter how many

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问题     Any physical theory is always provisional, in the sense that it is only a hypothesis; you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory. On the other hand, you can disprove a theory by finding even a single observation that disagrees with the predictions of the theory. As philosopher of science Karl Popper has emphasized, a good theory is characterized by the fact that it makes a number of predictions that could in principle be disproved or falsified by observation. Each time new experiments are observed to agree with the predictions the theory survives, and our confidence is increased; but if ever a new observation is found to disagree we have to abandon or modify the theory. At least that is when is supposed to happen, but you can always question the competence of the person who carried out the observation.
    In practice, what often happens is that a new theory is devised that is really an extension of the previous theory. Fox example, very accurate observations of the planet Mercury revealed a small difference between its motion and the predictions of Newton’s theory of gravity. Einstein’s general theory of relativity predicted a slightly different motion from Newton’s theory. The fact that Einstein’s predictions matched what was seen, while Newton’s did not, was one of the crucial confirmations of the new theory. However, we still use Newton’s theory for all practical purposes because the difference between its predictions and those of general relativity is very small in the situations that we normally deal with. (Newton’s theory also has the great advantage that it is much simpler to work with than Einstein’s!)
Newton’s theory of gravity was corrected by Einstein’s theory because of______.

选项 A、a new hypothesis about gravity
B、careful measurements of Mercury’s motion
C、new practical considerations of Newton’s theory
D、newly predicted observations

答案C

解析 文章第二段第二句“对水星的精确观测体现出水星的运动与牛顿万有引力理论预测有细微的差别,爱因斯坦的广义相对论与牛顿的理论预测也差别甚微,而事实上,爱因斯坦的预测与所观察到的事实相吻合,牛顿的理论却不是这样,从而成为证明爱因斯坦新理论的其中一个关键事实。”因而选择答案B。
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