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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Quantum teleportation + time dilation = time travel? [closed]

Thought of this a while back and thought it was pretty funny, not sure if there's been similar ideas discussed elsewhere. I can think of at least 2 reasons this won't work: 1) As far as I know, ...
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32 views

Time Travel Plausible? [closed]

The question of possibly achieving time travel has been exhaustively deliberated over and over again but in the modern era of new discovery and technological advancment, can we reexamine/rethink its ...
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58 views

A possible proof that time traveling to the past with the aid of a wormhole is impossible?

Suppose a wormhole connects two part of the place where I live. I find myself in a spaceship attached to one side of the hole, and my wife on the other side, so we can see and talk to each other. Now ...
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61 views
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30 views

Travelling backwards in time - is it possible? [duplicate]

Einstein predicted that gravity bends spacetime such that travelling through time is possible; but only forward in time. According to General Relativity we can travel in the future, but not backwards ...
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1answer
107 views

Speed of light or speed of time?

Proxima Centauri is about 4.22 Light Years, so if there is anyone that could see us, the image of us would be 4.22 years old, if we depart at 99.99% the speed of light we would arrive almost instantly ...
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4answers
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Height Issues of the Time Traveler [duplicate]

A person from the year 2250 goes back in time. They go back 60 Million years, because they want to observe dinosaurs. Imagine their surprise when they see T-Rex's running around like little ...
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2answers
126 views

Why time slows only for moving object and not stationary observer? How the “stationary” & “moving” are decided? [duplicate]

Explanation for the questions in the title: According to the the (special theory of) Relativity, if an observer is stationary and sees a fast moving object then time runs faster for the observer ...
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2answers
122 views

Can multiple timelines exist according to theoretical physics? [closed]

Multiple timelines is not a reality yet (as of 2016's science and technology), but exists only in Marvel/DC universe. It is something that is used to explain the paradox of time-travel. If you go back ...
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3answers
203 views

How can the past, the present and the future coexist at the same time? [closed]

We all heard it many times, the theory of Time suggest it is parallel rather than being linear. This leaves the door opened for alternate realities and well, immortality. However, even after reading ...
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1answer
76 views

Kerr spacetime and Carter time machine

In the Boyer-Lindquist-Block III (inside the inner event horizon) exists the so-called Carter time machine. There we can show that for every two points $p,q$ there exists a future-pointing timelike ...
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Traveling through time, reaching the past - POSSIBLE? [closed]

I was obsessed in studying the "faith" and I've made several great discoveries. I don't want to publish anything yet, but I have a semi-proven (proven partially) / theories / so I am curious on bones. ...
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1answer
105 views

Time Travel: Is it Possible to return to an earlier time? [duplicate]

(Please note: I've seen some other questions asked like the one I myself am asking, I realize that I am indeed late to the party, but I am genuinely curious and none of the previous answers have ...
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6answers
143 views

Wouldn't backwards time travel break the law of conservation of mass? [closed]

We know from the law of conservation of mass that the amount of mass in the universe is constant. Suppose there were a way for a person to travel backwards in time. Let's call this mass $m_t$ for some ...
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Traveling to the future is possible, but not to the past? [duplicate]

I understand how going to the future is possible: If you go really fast, time around you slows down for observers. But is it true that time traveling into the past isn't even theoretically possible?
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2answers
106 views

Backwards in time?

A “Universe Today” article titled “Galaxies Are Moving Away From Us Faster than the Speed of Light” prompted the following question, which the author of the article was unable to answer: “Would such ...
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1answer
83 views

Tomorrowland movie and tachyons? [duplicate]

Would be possible if tachyonic existed to send info to the past or see the future? since the tachyons according to special relativity could travel to the past? i have searched in wikipedia and the ...
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1answer
91 views

Is this a good argument against time travel? [closed]

Two fermions in two different points of space cannot be made to exist in the same point of space. It follows then that two fermions in two different times cannot be made to exist in the same time. ...
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2answers
282 views

Communication back in time?

On the wikipedia page for time travel, it mentions that Robert Forward said (theoretically, unknown since we don't have a working theory of quantum gravity) that if a heavy nucleus was subjected to an ...
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3answers
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At what rate would I travel back in time at $2c$? [closed]

I was thinking about Einstein's equations and the solutions using imaginary mass and imaginary time. How fast would I have to travel over $c$ to be traveling back in time at minus one meter per ...
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1answer
274 views

Certain doubts regarding the movie 'Interstellar' [closed]

In the movie, or rather a scientific fiction, Interstellar, we saw in the last part, that the actor falls into the black hole, travels in time, which is a dimension inside the black hole, and then, ...
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1answer
70 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 ...
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3answers
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Impossibility of time travel due to energy conservation?

I just watched the movie Terminator Genisys (It wasn't as bad as people say) and started pondering time travel. While pontificating and stretching my limited remembrance of AP Physics, science ...
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2answers
161 views

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

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 ...
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0answers
69 views

Compactly generated vs. compactly constructed causality violating region?

I am currently trying to grasp the nuance between a compactly generated future Cauchy horizon (as per Hawking's chronological protection conjecture) and a compactly constructed causality violating ...
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2answers
39 views

Is there a time difference for people traveling at different speeds during a long period of time?

I'm just throwing this out there for discussion/answering: If person A sat in a chair all his life, in a house on earth (let's say 100 years), and person B flew around in earth's atmosphere at let's ...
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1answer
120 views

Naked singularity: how would it behave?

We know that the theory of cosmic censorship prevent singularities from existing without an event horizon that hides them from the Universe. Now let's assume that this theory is somehow false, and a ...
3
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198 views

Closed timelike curves in the spin-2 gravity formalism

Let's say we take some topologically trivial CTC spacetime, like the Gödel metric: $$ds^2 = -dt^2 - 2e^{\sqrt{2}\Omega y} dt dx - \frac{1}{2}e^{\sqrt{2}\Omega y} dx^2 + dy^2 + dz^2$$ And then I ...
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2answers
242 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 ...
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3answers
177 views

Closed timelike curves in the region beyond the ring singularity in the maximal Kerr spacetime

The region beyond the ring singularity in the maximal Kerr spacetime is described as having closed timeline curves. Why and/or how is the question. Now if you look a Kruskal-Szkeres Diagram (or a ...
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2answers
78 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
2
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1answer
77 views

Do Einstein's equations allow multiple solutions that agree in a neighborhood of a spacelike hypersurface?

This question is an extension of my a question that I have recently asked: Why doesn't a global frame of reference exist for GR?, where it was recommended that I post another question (so I am ...
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3answers
805 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 ...
3
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1answer
117 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 ...
3
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0answers
202 views

Is This A Working Time Machine? [duplicate]

picture taken from this video for those who do not like to click on youtube links youtube video - retrocausality through Double Slit & Bose The answer will probably be no, but i am interested ...
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2answers
92 views

Does traveling through a wormhole cause you to go back in time?

Here is a hypothetical scenario: You have 2 planets A and B which are 10 light years apart. If I take a wormhole from A to B and I look at planet A through a telescope it would seem like it is 10 ...
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1answer
73 views

Time relativity / paradox [duplicate]

After watching the movie Interstellar, the theory of time relativity / paradox really mind-boggles me. If it is true that gravity controls everything even to the extent of time, then it might as well ...
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1answer
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Cosmic string & grandfather paradox

Cosmic string was proposed several decades ago and there are claims stating it can span across the length of the universe and is less than an atom thick. How does a broken pieces of these cosmic ...
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Gödel's solutions to Einstein's relativity equations and their consequences

Gödel gave certain solutions to Einstein's relativity equations that involved a rotating universe or something unusual like that; that predicted stable wormholes could exist and therefore time travel, ...
4
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1answer
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If a particle travelled in a closed timelike curve, would it look like a virtual particle-antiparticle pair?

In Feynman's single-electron hypothesis, he reaches the conclusion that a particle travelling backwards in time will look like its antiparticle. So if we have a particle travelling a closed time-like ...
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6answers
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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 ...
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1answer
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Are Asimov's short duration spacetime “jumps” feasible? [closed]

In books of science fiction (Asimov) I saw the fancy idea of a "jump" over a space-time interval, (i.e. at superluminal velocity and for a VERY SHORT time). The result was landing in another region of ...
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2answers
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Does information paradox in the Many Worlds interpretation cause a problem? [closed]

I'm taking a philosophy of time travel class. In one of the lectures, the teacher was discussing problems with the Many Worlds interpretation. He talked about how since anything that can possibly ...
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2answers
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Can you see back in time? [closed]

When you look at the stars, the light that you see is probably hundreds of years old. Which means that you don't know if they still exist. Does all this mean, that if you fly in a speed faster than ...
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2answers
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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, $x$ ...
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1answer
147 views

Navigating a Time Machine

Notes: The background for this question is working out details of a sci-fi story. Answers to the effect of "time travel isn't possible" or "FTL isn't possible" are therefore not helpful. I'm looking ...
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1answer
86 views

How can time-travel be possible if speed is relative? [duplicate]

I have heard that time-travel is possible...relative to some observer. So, as I understand it, the following example would be accurate: There are two twins- TwinA and TwinB. Both have very accurate ...
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2answers
99 views

De facto superluminal travel?

It seems that the limitation to subluminal travel can be practically circumvented (so to speak...not breaking any physical laws here) if we consider the viewpoint of the traveler, not some outside ...
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1answer
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Are closed timelike curves generic feature of ANEC-violating stress-energy tensor?

Kip Thorne has shown that in order to create closed timelike curves (CTCs), one needs stress-energy tensor $T^{\mu\nu}$ that violates averaged null energy condition (ANEC). Will $T^{\mu\nu}$ with ...
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Thought experiment regarding perpetual motion machines and paradoxes [closed]

A paradox (Ex.: if someone goes back in time to kill their own grandfather, then they won't exist, but then they wouldn't be able to go in time to kill their grandfather, but then they WOULD exist, ...