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

游客2025-02-01 30

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] From the second paragraph, we learn that ______.

选项 A、it is impossible for someone to change what has happened
B、it is possible for someone to change what has happened
C、it is impossible for someone to change the fact that he is a part of the past
D、it is possible for someone to change what has happened except the fact that he is a part of the past

答案 D

解析推断题型见第二段：当时间旅行者试图改变过去，这种似非而是的情况就出现了，当然这是不可能的。但是这并不妨碍某人成为过去的一部分。假设这位时间旅行者回到过去并从凶手手中救下一位年轻姑娘，这位姑娘后来长大成人成为他的母亲。这个偶然的循环现在就是首尾一致而不再是矛盾的了。这种偶然的一致也许要对时间旅行者能够做的事加以限制，但这丝毫也不排除时间旅行的可能性。据此推断选项C为答案。

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