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Questions tagged [time-travel]

Time travel is the concept of moving between different points in time, often instigated by non-trivially topology of space-time, such as a wormhole. DO NOT USE THIS TAG for questions on changes of coordinate systems, changes of time coordinate, or topologically trivial 'twin paradox' settings.

Time travel is the concept of moving between different points in time, often instigated by non-trivially topology of space-time, such as a wormhole. DO NOT USE THIS TAG for questions on changes of coordinate systems, changes of time coordinate, or topologically trivial 'twin paradox' settings.

220 questions
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Is travel to the distant future possible without massive energy expenditure?

Well-known physics establishes that, compared to some reference frame (I'll denote as "stationary" here), one can do several things to start at rest, end at rest, and experience less time than objects in the stationary reference frame do, although…
Alan Rominger
  • 21,047
4
votes
3 answers

Time travel in the past

The past weeks I watched some episodes from "Through the Wormhole" with Morgan Freeman. When talking about traveling back in time, they said you can only travel back up to the date when the first time travel occured. So, if for instance time travel…
Fofole
  • 607
4
votes
2 answers

Why is the probability that Kip could go back and kill his grandfather $10^{-10^{60}}$?

In The Universe In A Nutshell, page 153, Hawking says that The probability that Kip could go back and kill his grandfather is $10^{-10^{60}}$. How do we get this result?
Swapnanil Saha
  • 777
3
votes
1 answer

What kind of discovery would prove the impossibility of time travel?

Bearing in mind that: "Time travel" does not have one fixed definition. "Proof" in physics is never absolute or final as in mathematics. Except logical arguments which lead to paradoxes, what kind of discovery would prove the impossibility of time…
blackened
  • 295
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vote
2 answers

Does Stephen Hawking not believe in Negative movement?

Possible Duplicate: Is it possible to go back in time? Is time travel possible? According to Stephen Hawking, time travel to the future is not only possible but proven, however time travel to the past is impossible, however this doesn't make…
guideX
  • 21
0
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0 answers

Possibility of Time Travel?

Is time travel still considered as a possibility? What does the newer theories like string theory, M theory, etc. say about it.
Koushik
  • 241
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2 answers

Why are so many time-travel paradoxes assuming that the future is still valid?

It's a bit hard for me to explain what I mean by "the future is still valid", but bear with me. And I hope I'm not asking something incredibly stupid ;) I'll refer to my version of time travel as "linear time-travel" for a lack of a better…
Katai
  • 172
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Opinions on the Grandfather Paradox

According to the grandfather paradox, the notion of changing events that have occurred in the past is logistically impossible due to the fact that the events have already occurred. This has lead many physicists to believe that backwards time travel…
Charlie
  • 271
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how could I exist where I did not exist in the past?

If I was able to go back in time via Machine or whatever, would traveling back in time not create a paradox? I was not there, so how could I exist where I did not exist in the passed? i would have to assume that we could never go backwards in time…
Sifimichael
  • 113