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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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 ...
9
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4answers
2k 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 ...
24
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4answers
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How does faster than light travel violate causality?

Let's say I have two planets that are one hundred thousand lightyears away from each other. I and my immortal friend on the other planet want to communicate, with a strong laser and a tachyon ...
2
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4answers
613 views

Can causality be violated?

A common justification for prohibiting many unusual phenomena such as faster than light travel is that if they were possible, causality would be violated. Let's define causality as: You cannot ...
17
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3answers
3k 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 ...
12
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6answers
805 views

Is time travel impossible because it implies total energy in the universe is non-constant over time?

I have always argued with my friends regarding Time Travel that it is impossible. My argument has been that it will destroy the theory that all the energy in the universe is constant since when one ...
2
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2answers
494 views

What is time teleportation?

I read this article about time teleportation. Can someone explain the concept better?
5
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2answers
617 views

Wormholes, time travel, and time dilation

I believe I understand the "wormhole time machine" now, but still have one question regarding what happens if you enter the stationary mouth. A wormhole is created and (of course) has two mouths, $x$ ...
3
votes
2answers
720 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 ...
1
vote
1answer
332 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 ...
19
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4answers
3k views

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 ...
8
votes
4answers
857 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 ...
9
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3answers
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Time travel outside of light cone without causality violation

If one is able to travel into the past but at a spatial distance that puts him outside of his own past light cone would this be considered a causality violating trip? Looking at a Minkoski diagram, it ...
2
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2answers
589 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 ...
16
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6answers
1k views

How to argue that time travel to past would not be possible even in future?

I am a science fiction writer. I know how to time travel to the future (using black hole or speed). But I need to argue in my novel that time travel to the past might not be possible. Is there a way ...
8
votes
2answers
672 views

Is it possible to produce gravitational waves artificially?

Why don't they make a ball with irregularities, say the size of a tennis ball, then spin it very rapidly, so it would produce gravitational waves like a spinning star with irregularities on it? Is ...
2
votes
2answers
129 views

What would a closed timelike curve look like?

What exactly are closed timelike curves. In a metric in which they would exist, what would they look like. What would it be like travelling through them? It obviously wouldn't look like a door. Would ...
2
votes
1answer
279 views

Does the concept of a wormhole violate the law of mass-energy conservation?

If my understanding of wormholes is correct, anything that moves into a wormhole can be transported from one region of space-time to another. Consider a situation where an object of mass $m$ in space ...
0
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1answer
44 views

Traveling Back in Time at the End of the Universe [closed]

I apologize if this question may seem fantastical. Since the heat death of universe is said to be inevitable, is it possible to travel back in time to a younger universe when the time comes? Is that ...
3
votes
1answer
106 views

Is this one of the reason we can't travel in time? [closed]

I'd like to ask a question that is not in my field but it's bothering me. Based on that, I'm sorry if I make dumb mistake in my assumptions. The idea of travelling in time means "going" at some ...
0
votes
1answer
382 views

Time travel, is it possible? [duplicate]

I see there are many questions with this title, but this one is different, so please give it due thought: Is time travel possible? If so, Can we go both forwards and backwards in time? Paradox: I ...
0
votes
1answer
144 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.
-1
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2answers
67 views

is there a way to capture scenes from past? [closed]

Is there a way to capture scenes from past for ex/ capturing someones sound which lived before long time ago.. if yes, how? and if no, why? Regards
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1answer
113 views

Grandfather Paradox [closed]

This question related to the Grandfather Paradox. Assume that time travel to the past is a reality. What experiment/test could the time traveler perform in order to determine if he is in his own ...