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回到未來的是非

Stephen Hawking 霍金, in the episode "Can We Travel In Time?" of his TV series Genius, explains why he thinks the laws of nature (as we know today) do not support backward travel in time. His definition of time travel is having a physical presence allowing participation in events happening at that time and space.

MH370 disappeared about 2¼ years ago. We don't know where it is because we weren't looking as it happened. For many, it would be beyond words to be able to go back in time to alter that tragic event. Even if we cannot go back in time to alter the event, is there any value to be able to look back in time to see what happened?

發表於 Posted on: 2016-07-11 0:57

LatentNightCrawler
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A space alien, 2.25 light-years away, could be observing earth with a telescope pointing at the Indian Ocean right now. That observer would be able to see the MH370 event unfolding as if it is just happening. This is because the light from earth showing that event has just reached that observer. If that observer would 'beam' us the information, in another 2.25 years, we would be able to see what happened as well. That is a form of non-participating time-travel into the past by 'catching' the light. Actually, that's how we observe the birth of many celestial bodies that happened billions of years ago.

Hawking explains traveling to and participating in the future is possible. However, it may not be what you think.

發表於 Posted on: 2016-07-11 1:06

LatentNightCrawler
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In the movie Interstellar 星際啟示錄, it talks about the passing of time slows down when staying near a massive object, such as a black hole. This phenomenon is known as gravitational time dilation according to Einstein's theory of relativity. Say, on the first day of 2000, you 'zapped' from earth to a planet near a black hole. After living there for 25 years, you decide to return to earth. By your calendar, on the first day of 2025, you 'zap' back on earth. You may very well be finding the earthlings celebrating their 2030 New Year. This gives the appearance that you have traveled 5 years into the future by living near a black hole. In reality, you are comparing clocks progressing at different rates.

According to Hawking, you may be able to 'travel' to the future to find out the winning numbers of a 六合彩. However, you would not be able to travel back in time to buy the ticket before the drawing starts. What a bummer!

發表於 Posted on: 2016-07-11 1:18

LatentNightCrawler
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