Questions tagged [closed-timelike-curve]
The closed-timelike-curve tag has no usage guidance.
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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 ...
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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 ...
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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 ...
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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 $(M, g)$...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
user338734
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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.
...
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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 ...
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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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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 ...
user226436
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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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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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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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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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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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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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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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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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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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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 ...
