Questions tagged [closed-timelike-curve]

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Can you go back and forth through time when inside a black hole?

Inside the event horizon of a Schwarzschild black hole the radial coordinate becomes timelike and the time coordinate becomes spacelike (they change signatures). I read that timelike coordinates are ...
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1answer
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Pair creation and annihilation and Wheeler's one electron universe

I stumbled upon Wheeler's idea that there could be only one electron. If I understood correctly, basically the idea is that one electron moves forward and backward in time such that it appears as if ...
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Misner space - closed timelike curves

Could someone give me a good resource to read about closed timelike curves in Misner space? Somewhere where they are actually derived and some comments are made for the simple 2D Misner space?
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Is there any well-known holographic duality that allows wormholes and CTCs to exist?

Is there any well-known holographic duality (like AdS/CFT or holographic principle in string theory/black holes) that contains wormholes and Closed Timelike Curves? I was discussing this with a ...
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Would CTCs in wormholes change physical laws?

A wormhole is a speculative structure linking disparate points in spacetime, and is based on a special solution of the Einstein field equations solved using a Jacobian matrix and determinant. (https:...
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2answers
85 views

Would non-hyperbolic space times have different laws?

Would a non-hyperbolic model of our universe have fundamentally different laws than our universe? For example, in Gödel's metric, its laws would be described by general relativity. But if the Gödel ...
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1answer
89 views

Time Travel, CTC and Causal Loop

What is the difference between a closed timelike curve and a causal loop? If someone is travelling in a closed timelike curve, are they also in a causal loop?
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Brouwer fixed point theorem

How does the Brouwer fixed point theorem (which provides a solution to the photo camera paradox of a causal loop) generalise to show that objects in closed time-like curves do not violate the second ...
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1answer
299 views

Correlators for space-like photon bouncing

Consider the diagram below of two detectors-emitters exchanging photons: Thin lines are null-paths between detectors. Detectors are also synchronized in such a way that measurements outside the blue ...
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Is a time loop possible? [duplicate]

Let's say that hypothetically we could travel faster than light. Would a ship travelling at lightspeed or faster than light travel create a time loop where it makes the same trip over and over again ...
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1answer
72 views

Closed Trajectories in wormhole

This might seem trivial but if I want to go about finding closed trajectories in a wormhole with a metric: $$ds^2=-dt^2+dr^2+(b^2+r^2)(d\theta^2+sin^2\theta d\phi^2)$$ how should I approach that? Is ...
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2answers
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Simplest mathematical model of a causal loop

Is there a simple mathematical model for causal loops? The physics seems pretty involved, but I'm wondering if I can understand just the math of the final answer (similar to how one can understand ...
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3answers
348 views

Closed spacelike vs Closed timeline curves (or rather loops)

Reading John Rennie's answer, it made it very clear as to why it is justified to talk of time as a coordinate. So, for now we put time and space on the same footing i.e. consider them dynamical ...
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Role of the observer in Gödel's universe

I am here to clarify myself about the role of the observer in Gödel's solution (1949) of Einstein's field equations. The Universe we are dealing with is anisotropic, since the axis of rotation ...
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89 views

Causally benign spacetimes and the Minkowski torus

A notion encountered in field theory on non-globally hyperbolic manifolds is the notion of a spacetime being causally benign with respect to some field $\phi$, which is defined thusly : A ...
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Physical reality of inner event horizon and inner ergosurface in a rotating black hole in D. Wiltshire et al. “The Kerr spacetime”

In chapter 1/The Kerr spacetime-a brief introduction by Matt Visser of D. Wiltshire, M. Visser, S.M. Scott "The Kerr spacetime - Rotating black holes in general relativity" the author presents a ...
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120 views

Does our universe admit of a global time function?

My understanding of a global time function is this: a function whose value always increases as a body moves into its local future. My confusion is this: I gather that the Gödel Universe is bizarre ...
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Accelerating thin shell wormholes and closed timelike curves

The classical example of the conversion of a wormhole into a time machine is to consider two wormholes, one stationary and another one accelerating for some period before going back to its original ...
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1answer
374 views

What is a closed timelike curve? [closed]

I was wondering if anyone could explain to me what a closed timelike curve is? From Wikipedia: "In mathematical physics, a closed timelike curve (CTC) is a world line in a Lorentzian manifold, of ...
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1answer
113 views

What would a closed timelike curve be like? [closed]

I have a few questions about CTC: What would CTC look like from the outside? Would every loop be the same? What would happen if the cause of CTC disappear? (e.g. Tipler cylinder stopped spinning)
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Are time loops real?

I'm new to physics and I was wondering if time loops (like those seen in the movies Groundhog Day or Edge of Tomorrow) possible?
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1answer
1k views

Wormholes and Closed Time-like Curves

I've been doing a presentation on Wormholes for my Science class, and I've been wondering about the difference of Closed Time-Like Curves and Wormholes, as most articles I read can't truly explain the ...
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105 views

Experimental test for a universal scale closed timelike curve?

So recently, in chat, I was interested in about what if our universe contains only one CTC (thus making it unlike the Gödel metric, van Stockum dust where there can be more than one CTCs found) and ...
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1answer
166 views

Geodesics and CTC

What is the exact explanation for which CTC (closed timelike curves) are not geodesics? I have already looked up in many papers but none provides the exact reason.
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1answer
105 views

Time travel backwards, would anything be observable? [closed]

I'm by no means a physicist theoretical or otherwise, so please do excuse any things that I may be ignorant of (likely a very long list). If by whatever mechanism a traveller were able to travel back ...
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1answer
479 views

What is the latest science on closed timelike curves? [closed]

In Scientific American (Sept 2014), Lee Billings writes: Lloyd, though, readily admits the speculative nature of CTCs. “I have no idea which model is really right. Probably both of them are wrong,” ...
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475 views

Closed timelike curves in the Kerr metric

I just read in Landau-Lifshitz that the Kerr metric admits closed timelike curves in the region $r \in (0, r_{hor})$ where $r_{hor}$ is the event-horizon ( I am talking about the case $|M|>|a|$ (...
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3answers
208 views

Detection of closed timelike curves (CTC)

I have a question. Are there any methods for detecting CTC? Is there a possibility of designing modern physics experiment in order to confirm / refute the possibility of CTC at any given time in a ...
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Do any quantum gravity theories deal with closed timelike curves?

As far as I'm aware, there are no quantum gravity theories that deal directly with closed timelike curves. Some of them (like canonical quantum gravity, causal dynamical triangulation and loop quantum ...
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1answer
279 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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1answer
116 views

Numerical relativity in causally pathological spacetimes

To perform numerical relativity simulations one almost universally adopts the so called "3+1" approach: spacetime is divided up into spacelike slices, each representing a "moment in time". After some ...
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2answers
447 views

Homotopy proof of the lack of foliation of the Gödel metric

A common proof of the lack of foliation of the Gödel universe, apparently mostly copy pasted from Hawking and Ellis, goes thusly : A closed timelike curve must cross a spacelike hypersurface without ...
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2answers
397 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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1answer
531 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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Chronology protection for non-geodesic CTCs and imprisoned curves

As far as I can make out, the quantum part of the Chronology Protection Conjecture hinges on the fact that in curved space, in the semiclassical approximation, the stress energy tensor contains a term ...
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1answer
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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
113 views

Why can't a particle rotate opposite to the central mass within the ergosphere?

Wiki says about the Kerr metric: A moving particle experiences a positive proper time along its worldline, its path through spacetime. However, this is impossible within the ergosphere, where $g_{...