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Questions tagged [closed-timelike-curve]

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Do closed timelike curves take a traveler further back in time than when they entered? [closed]

I am very well aware of the paradoxes associated with existence of closed timelike curves (CTCs). For a moment, let us assume they exist and somehow all paradoxes are resolved. Can a CTC ever take an ...
manyworlds's user avatar
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How does loop quantum gravity handle spacetimes which aren't globally hyperbolic, like the Kerr metric?

Loop quantum gravity assumes spacetime is globally hyperbolic. However, the interior of a Kerr black hole isn't globally hyperbolic, containing closed timelike curves. So, how are Kerr black holes ...
Zee's user avatar
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Ryu-Takayanagi surface for geometry containing closed timelike curve

Is the Ryu-Takayanagi formulation (and its extensions) applicable for spacetimes containing closed timelike curves (CTCs)? I have gone through the assumptions that go into their formulation but as far ...
physmath17's user avatar
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Berry phases in closed timelike curves

Does anyone know what the physical significance of a Berry phase induced by parallel transport around a closed timelike curve would be? There is a preprint from 1994 describing that parallel transport ...
manyworlds's user avatar
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Confusion about local Minkowski frames

This is sort of a follow-up to the question I asked here:  Confusion about timelike spatial coordinates The important context is that we imagine a metric that, as $t\rightarrow\infty$, approaches the ...
Aidan Beecher's user avatar
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Confusion about timelike spatial coordinates

I'm pretty new to general relativity, and I'm self-studying it using Sean M. Carroll's text on the subject. In Section 2.7, he introduces the notion of closed timelike curves. He gives the example of ...
Aidan Beecher's user avatar
-1 votes
1 answer
57 views

Why does the timelike killing vector become spacelike inside the ergoregion?

Why does the timelike killing vector become spacelike inside the ergoregion? Some textbooks make this claim and move on to explain negative energy, but I could not find any proof for this claim. I can'...
Gene's user avatar
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Is the spinning Cosmic String spacetime totally vicious?

The spacetime $(M,g)$ is given locally at each point by the metric: $$g= -(dt + a \, d \phi)^2 + d\rho^2 + \kappa^2 \rho^2 \, d\phi^2 + dz^2 \ \text{where} \ \ a > 0$$ This is the spacetime of a ...
Bastam Tajik's user avatar
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Does the van Stockum dust have closed timelike geodesics?

We work under this explicit form of the metric: $$ds^2 = -dt^2 - 2br^2\,dtd\phi + (1-b^2r^2)r^2\,d\phi^2 + e^{-b^2r^2}(dz^2 + dr^2).$$ Since the metric coefficients only depend on $r$, we can ...
nli2095's user avatar
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In Relativity theory, is chronological relation an order relation?

Let $(M,g)$ be a (Lorentz) spacetime, i.e a connected smooth manifold $M$ with a metric tensor field $g$ and a time orientation called future direction which is defined by a smooth timelike vector ...
PermQi's user avatar
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Causality violation in Kerr metric

my professor told me that in Kerr metric, there is a zone of causality violation around the ring singularity, but he was saying this in the context of $M^2>a^2$, does this also apply to the cases ...
minime's user avatar
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Can a CTC contaning spacetime be purely electric?

Take a time-oriented Lorentzian manifold $(M, g)$ where $M$ is a topological 4-manifold and $g$ a Lorenzian metric. Assume such a spacetime contains a CTC. Since the manifold is time-oriented, one can ...
Bastam Tajik's user avatar
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2 votes
2 answers
180 views

Does causality forbid time travel?

If causality is an axiom or a fundamental law in physics, would the existence of causality be a reason which forbids time travel? Because time travel could break causality so we see first the effect ...
Jose Perez's user avatar
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Visualizing CTC - is it related to a "periodic wick rotation"?

As far as I understand Wick rotation, it means the mathematical transformation $$ ct → jct $$ Where $j$ is imaginary unit. While reading on CTC (closed timelike curves) in the Gödel metric I came ...
Awe Kumar Jha's user avatar
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1 answer
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A question about the topology of spacetime and the existence of CTCs

Let $(M, g)$ be a smooth Lorenzian time-oriented manifold. Is it possible for the Lorenzian metric induced topology to be different from that of the manifold topology, without CTCs? We know that the ...
Bastam Tajik's user avatar
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No inconsistencies due to closed timelike curves in General Relativity

Is there anything wrong with the following argument ruling out inconsistencies with closed timelike curves? Math A solution in the context of General Relativity is a pseudo-Riemannian manifold $(M, g)$...
TomS's user avatar
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A question on the causal hierarchy/ladder and the existence of CTC

What does the existence of CTC imply for the Causal Structure of the spacetime? Can a strongly causal spacetime have any CTC[without fluctuating the metric]? Is there any such example? Can someone ...
Bastam Tajik's user avatar
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7 votes
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Meaning of closed timelike curves

There are spacetimes that admit closed timelike curves (for example a cylinder, Gödel's Universe, the Kerr-Solution). But what does it physically mean to move along a closed timelike curve? If i move ...
Mac Menders's user avatar
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Why can't travel through a closed timelike curve violate the Novikov self-consistency principle? [duplicate]

The Novikov self-consistency principle prevents a paradox in which a billiard ball is sent to its past through a closed timelike curve (allowed under general relativity) such that it collides with its ...
T Scherer's user avatar
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Why can't travel through a closed timelike curve violate the Novikov self-consistency principle?

The Novikov self-consistency principle prevents a paradox in which a billiard ball is sent to its past through a closed timelike curve (allowed under general relativity) such that it collides with its ...
T Scherer's user avatar
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How does numerical simulation of GR work in the case of closed timelike curves?

In all cases I'm aware about so far, when you want to do a numerical simulation of a physical system, you invoke the initial conditions and program how the system evolves in time. Now presumably, I ...
Maximal Ideal's user avatar
2 votes
2 answers
617 views

Confused on the types of solutions to Einstein field equations in General Relativity

Context While reading about the types of solutions to The Einstein Field Equations in General Relativity, I came across the following article. Where they explain that Karl Schwarzschild provided the ...
William Martens's user avatar
4 votes
4 answers
963 views

Closed time loops and causality in general relativity

I always read that GR does not seem to prevent closed time loops. This does not sound too crazy if you could somehow create a traversable wormhole (and move one of the ends fast and long to make the ...
user avatar
5 votes
1 answer
305 views

Why does a null entropy variation along a closed timelike curve imply a reversible process?

Carlo Rovelli in one of his articles from 2019 (reference: https://arxiv.org/abs/1912.04702) argues that time travel into the past are thermodynamically impossible: For instance, if we want to travel ...
MattG88's user avatar
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Impossibility of closed timelike curves

Hawking's Chronology Protection Conjecture says that the laws of nature must always conspire to prevent a CTC from forming. Why can't we conclude that this is proven? An inconsistent CTC is s ...
JeffK's user avatar
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1 answer
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Could Gott's Cosmic String Time Machine hypothetically be used as a poor man's Alcubierre drive?

I have read much speculation about Gott's theoretical use of cosmic strings for time travel, but if the colliding cosmic strings accelerated the spacecraft faster than light, as Gott theorizes, could ...
Ben Warner's user avatar
2 votes
1 answer
435 views

Where is the CTC region of a Kerr Black Hole?

CTCs are found in the region where $r < 0$ . That should be just inside the ring singularity, since in Boyer Lindquist coordinate system $r = 0$ means ring singularity. Does that mean this image ...
Nayeem1's user avatar
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2 votes
1 answer
160 views

ADM formalism, closed timelike curves and chronological protection conjecture

Is it correct that based on the premise of foliation by Cauchy surfaces the ADM fomalism restricts the set of solutions for general relativity to causal manifolds and therefore excludes closed ...
TomS's user avatar
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1 vote
0 answers
72 views

Should time be a loop or a line?

It's interesting to see that torus was so popular in physics, that it worked so well. There was famous Gauss–Bonnet theorem which stated basically $$\oint_S K dS= 2\pi \chi(S)$$ where K was the ...
ShoutOutAndCalculate's user avatar
1 vote
1 answer
101 views

Does general relativity predict that it's possible to watch a process playing backwards?

My question is Let's say you have an object moving through space locally at less than the speed of light. Is it possible to watch that object playing backwards like a record spinning the wrong ...
Timothy's user avatar
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1 vote
2 answers
107 views

General Covariance & CTCs

Consider Minkowski space defined in coordinates $(t,x,y,z)$. Let us equip the manifold with a time orientation $$T = \frac{\partial}{\partial t}$$ such that $g(T,T)<0$, in $(-+++)$ signature, this ...
Joeseph123's user avatar
4 votes
1 answer
300 views

Warp drive causality issue, and a possible error in a paper?

Take a look at this paper on "Warp Drives and Causality:" https://doi.org/10.1103/PhysRevD.53.7365 The author attempts to argue that the Alcubierre Drive spacetime could exhibit Closed ...
Joeseph123's user avatar
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1 answer
145 views

Does faster than light lead to closed timelike curves?

If some signal can be sent to a spacelike interval then is it possible in some reference frame to have a close timelike curve? Novikov claims so in this paper. The argument lies below eq$7$ but ...
aitfel's user avatar
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2 answers
322 views

Do wormholes really allow us to travel back in time?

Theories surrounding wormhole based time travel are annoying me tonight... So the way time works is relative, right? The closer you are to the frame of reference, the faster time moves. So, if we use ...
Hazel へいぜる's user avatar
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1 answer
66 views

CTC, determinism and valuedness of Riemann tensor

What I understood is that By the math, the Riemann tensor is obtained by parallel-transporting a vector along a closed curve in the considered space, then apply Stoke's theorem. Now if physics is ...
QuantumPotatoïd's user avatar
1 vote
1 answer
127 views

In what sense does the "speed limit" $c$ prevent violations of causality? Could they be prevented some other way? [closed]

I have seen it said that if we want to avoid violations of causality (I can see why we would want to avoid that!), we need the information-transfer "speed limit" of c. I presume(?) this ...
Hamish Todd's user avatar
1 vote
1 answer
99 views

Classical Field Theory with Compact Time

How does one find solutions to a classical field theory (say, $\phi^4$ theory) when the time dimension is periodic (so in $\mathbb{R}^n \times T^1$ or other compact topology), especially if the ...
botsina's user avatar
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1 answer
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If the universe is closed, does that also mean time is closed?

Speaking just about space, we say that the universe is either open (topologically $E^3$) or closed (topologically $S^3$). But since a metric connection defines curvature on spacetime and not just ...
Cam White's user avatar
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-2 votes
1 answer
237 views

What Ron Mallett doing for time machine here? [duplicate]

Here Ron Mallett pouring liquid chemical on array of lasers for progress of time machine. I didn't understand it. Source What exactly Ron Mallett doing for time machine here?
Polly Man's user avatar
2 votes
0 answers
84 views

Closed Timelike Curves and relatively stationary wormholes

Apologies in advance if this question is off topic, I wasn't sure if this was the most appropriate SE forum or not. Wormholes are one of the most often cited examples of a possibility for faster than ...
alzee's user avatar
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1 vote
1 answer
86 views

Let $M$ denote a connected time-oriented Lorentzian manifold. If $M$ is compact then $M$ must have a closed-curve

Problem Let $M$ denote a connected time-oriented Lorentzian manifold. If $M$ is compact then $M$ must have a closed-curve. I don't know how to use this information that M is compact to obtain a ...
Powder's user avatar
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1 answer
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Is there any experimental evidence of CTC?

One consequence of general relativity is a solution called the closed time like curve or CTC...which could allow you to view a place at an earlier point in time or possibly even travel back in time. ...
Joeseph123's user avatar
2 votes
1 answer
224 views

Do superluminal worldlines constitute closed time-like curves under the right conditions?

A closed time-like curve is defined as a word-line that returns to its starting point, in the $x$, $y$, $z$, $t$ coordinates. So, for a chronology respecting observer, an object traversing a closed ...
CuriousDroid's user avatar
3 votes
1 answer
264 views

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 ...
Vilim Lendvaj's user avatar
1 vote
1 answer
162 views

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 ...
eeqesri's user avatar
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0 votes
0 answers
258 views

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?
QFT_groupie's user avatar
2 votes
0 answers
108 views

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 ...
user avatar
1 vote
0 answers
106 views

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:...
sztorwi's user avatar
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0 votes
2 answers
217 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 ...
sztorwi's user avatar
  • 91
2 votes
1 answer
281 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?
Maths's user avatar
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