Assuming that the engineering problems could be overcome, the production of

游客2024-01-01  9

问题     Assuming that the engineering problems could be overcome, the production of a time machine could open up a Pandora’s box of causal paradoxes. Consider, for example, the time traveler who visits the past and murders his mother when she was a young girl. How do we make sense of this? If the girl dies, she cannot become the time traveler’s mother. But if the time traveler was never born, he could not go back and murder his mother.
    Paradoxes of this kind arise when the time traveler tries to change the past, which is obviously impossible. But that does not prevent someone from being a part of the past.
Suppose the time traveler goes back and rescues a young girl from murder, and this girls grows up to become his mother. The causal loop is now self-consistent and no longer paradoxical. Causal consistency might impose restrictions on what a time traveler is able to do, but it does not rule out time travel per second.
    Even if time travel isn’t strictly paradoxical, it is certainly weird. Consider the time traveler who leaps ahead a year and reads about a new mathematical theorem in a future edition of Scientific American. He notes the details, returns to his own time and teaches the theorem to a student, who then writes it up for Scientific American. The article is, of course, the very one that the time traveler reads. The question then arises: Where did the information about the theorem come from? Not from the time traveler, because he read it, but not from the student either, who learned it from the time traveler. The information seemingly came into existence from nowhere, reasonlessly.
    The bizarre consequences of time travel have led some scientists to reject the notion outright. Stephen W. Hawking of the University of Cambridge has proposed a "Chronology protection conjecture," which would outlaw causal loops. Because the theory of relativity is known to permit causal loops, chronology protection would require some other factors to intercede to prevent travel into the past. What might this factor be? One suggestion is that quantum processes will come to the rescue. The existence of a time machine would allow particles to loop into their own past. Calculations hint that the ensuring disturbance would become self-reinforcing, creating a runaway surge of energy that would wreck the wormhole.  [br] The word "chronology" underlined in Paragraph 4 most probably means ______.

选项 A、outer space
B、time order
C、momentary action
D、processing order

答案 B

解析 词义题型本句意为:英国剑桥大学的施蒂芬•W•霍金提出“______保护假设”,这一假说认为这个偶然的循环/时空环是不存在的。因为本文一直讲的是时光机器和时间旅行者的问题,因此选项A.outer space太空;B.time order时间顺序;C.momentary action瞬间行为;D.processing order处理顺序;因此B是答案。“chronology protection conjecture,”表示“时序保护假设”。
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