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.

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If airplanes' highest speed depends directly on the air it is moving through and not the ground,

If airplanes' highest speed depends directly on the air it is moving through and not the ground, does it mean we can build a time machine if only the air moves near the speed of light?
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2answers
297 views

Is this closed time-like curve in a Godel universe a “circle”?

Would the observer moving along the circle in this Godel space-time diagram feel fictitious forces as though he is accelerating along a circular path or would he simply arrive at an earlier point in ...
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2answers
2k views

Does Stephen Hawking not believe in Negative movement? [duplicate]

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 ...
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4answers
144 views

Messing with the past: Endless loop, or alternate timelines? [closed]

Let's take the following scenario: A person finds a time machine. He uses it to travel to the past, and kills his grandparents. Now because of this, his parents are never born, they do not ...
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1answer
177 views

Can project LISA will bring us closer to time travel? [closed]

After looking at the current discovery of Higgs Boson and the next long term plans of NASA and ESA(European Space Agency), I can't stop myself asking about the possibilities in near future. According ...
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1answer
378 views

Energy balance of closed timelike curves in Gödel's universe

I recently read Palle Yourgrau's book "A World Without Time" about Gödel's contribution to the nature of time in general relativity. Gödel published his discovery of closed timelike curves in 1949. ...
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2answers
182 views

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?
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1answer
461 views

How is traveling back in time possible in theory according to some scientists? [duplicate]

Possible Duplicate: Is it possible to go back in time? Is time travel possible? I get the idea of traveling to the future and it makes perfect sense as we'd be somehow trapped in a ...
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1answer
139 views

Can we develop in the future a technology that can send a message to the past? [duplicate]

Possible Duplicate: Is it possible to go back in time? I believe that everything is possible in this world. If that can be done then why aren't we receiving any message from the future.
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3answers
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How does Time traveling work in practice?

There are multiple theories about time traveling. One is "proven": The time slows down according to your speed. The satellites in space are traveling faster than us, thus their clocks slows down a ...
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1answer
323 views

Time travel to future [duplicate]

Possible Duplicate: Is time travel possible? Is time travel possible? According to my friend, it is possible to go to the future but not the past. In Physics, particles move faster than ...
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1answer
714 views

Time traveling and Time dilation within a multiplayer videogame [closed]

First thing first, I'm looking to implement this within a multiplayer videogame as a "special" skill or powerup, but, I'm willing to build it upon a physics based explanation/theory. The question may ...
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2answers
292 views

how could I exist where I did not exist in the past? [closed]

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 ...
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2answers
660 views

Does superluminal travel imply travelling back in time?

Is this statement true? You can not travel back in time. If I travel fast enough the clock will start to go backwards, but that does not mean I am traveling back in time. It would only mean that ...
8
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4answers
788 views

Why should one expect closed timelike curves to be impossible in quantum gravity?

From the Wikipedia article, it seems that physicists tend to view closed timelike curves as an undesirable attribute of a solution to the Einstein Field Equations. Hawking formulated the Chronology ...
7
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3answers
375 views

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 ...
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4answers
1k views

Is time travel possible? [duplicate]

Time travel -- often featured in movies, books, or facetiously in conversation. There are also theories treating time as simply another dimension, which to the layperson might imply forward and ...
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1answer
487 views

Can the Universe create itself?--Is Gott's Use of CTC in Planck time or less valid?

My question is the title of a 1991 paper by Richard Gott and Li-Xin Li: http://arxiv.org/abs/astro-ph/9712344 and is also a subject of his popular book, "Time Travel in Einstein's Universe" Ultimately ...
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2answers
477 views

What is time teleportation?

I read this article about time teleportation. Can someone explain the concept better?
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4answers
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Wormholes & Time Machines - for *experts* in GR/maths

EDIT: Further clarification in the context of answers/comments received to 20 Jan has been appended EDIT: 21 Jan - Response to the Lubos Expansion appended [in progress, not yet complete] EDIT: 23 ...
3
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3answers
572 views

Time travel and nuclear decay

Reading a previous closed question an interesting variation has come to my mind. Suppose that time travel to the past was possible: I wait for an atom to decay and measure the time, $t_{1a}$ I ...
14
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7answers
3k views

Is time travel possible? Is it possible to go back in time?

I read somewhere that according to relativity, black holes and other space related stuff it is possible to jump into past. Is it possible for anything to go back in time either continuously or by ...
17
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3answers
2k views

What are some scenarios where FTL information transfer would violate causality?

I've always heard people saying, "Faster than light information transfer can't happen because it would violate causality! Effects can precede their causes!" However, I'm trying to think of a ...