Exploring Spacetime Propagation in Higher-Dimensional Relativity

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Discussion Overview

The discussion revolves around the propagation of soliton-like fields in higher-dimensional spacetime within the framework of General Relativity. Participants explore whether such propagation is feasible without divergence as it approaches a target, and whether General Relativity permits solutions that avoid backward in time causality violations.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions the possibility of soliton-like fields propagating in higher-dimensional spacetime without divergence, asking if General Relativity makes this impossible.
  • Another participant requests references for the concept of a "soliton-like field" and expresses skepticism about the question being suitable for a "B" level discussion, prompting inquiries about the original poster's background in relativity.
  • A participant provides a reference to a paper and discusses their extensive background in General Relativity, questioning whether the paper addresses solitons traveling at light speed or faster, and the implications of such speeds on causality.
  • There is a discussion about the necessity of a graduate-level understanding of both General Relativity and quantum field theory to engage with the referenced paper effectively.
  • Clarifications are made regarding the nature of the "soliton" in the paper, indicating it is a configuration of a quantum field rather than a particle, and that the paper discusses theories that may involve higher-dimensional spacetime.
  • Participants express a desire for comments on signal propagation in more than four-dimensional spacetime and seek additional references on this topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the feasibility of soliton-like field propagation in higher-dimensional spacetime or the implications of such propagation under General Relativity. Multiple competing views and uncertainties remain regarding the necessary background knowledge and the interpretation of the referenced paper.

Contextual Notes

There are limitations regarding the assumptions made about the background knowledge required to understand the discussed paper, as well as the scope of the theories presented in the reference. The discussion also highlights the complexity of the concepts involved, which may not be accessible without advanced study in the relevant fields.

bluecap
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What kind of spacetime structure can make the lines of a soliton-like field propagate in higher-dimensional space-time that do not diverge as they converge on the target. Does General Relativity make this just completely impossible? Or is there a solution of General Relativity that allows this? Would there be backward in time causality violations?
 
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Do you have a reference for the "soliton-like field" you are talking about?

Also, I'm extremely doubtful that this question can be answered at a "B" level. What background do you have in relativity?
 
PeterDonis said:
Do you have a reference for the "soliton-like field" you are talking about?

Also, I'm extremely doubtful that this question can be answered at a "B" level. What background do you have in relativity?

Here http://xxx.lanl.gov/abs/hep-ph/9904218. I have good background owning more than 8 books on General Relativity. Is the paper talking about soliton that travels at light speed or faster than light? Because if faster than light.. I know there would be frames in which it would appear to travel backward in time. Or if it less or just light spead. Is it talking about 5 dimensional spacetime? I know Einstein GR can be made to function in more than 4 spacetime coordinates. I just want some comments on signal propagation in more than 4d spacetime.. any papers along this line would be appreciated.
 
bluecap said:
Here http://xxx.lanl.gov/abs/hep-ph/9904218.

As I suspected, this is an "A" level reference and is not suitable for a "B" level thread. I have changed the level of this thread to "A".

bluecap said:
I have good background owning more than 8 books on General Relativity.

How many of them are graduate level textbooks? That's the background you need to be able to understand what the paper you linked to is talking about. You don't appear to have that level of background from your posts so far.

Not only that, but just a background in GR is not enough; you also need a graduate level background in quantum field theory in curved spacetime.

I'll try to respond to your questions as best I can, but I would strongly suggest taking the time to work through graduate level textbooks in both subjects (GR and QFT) before tackling this kind of paper. It's simply not written for a person who is not already an expert in the field.

bluecap said:
Is the paper talking about soliton that travels at light speed or faster than light?

No. The "soliton" in this paper is not a particle; it's a particular configuration of a quantum field in curved spacetime in which particles can propagate in the model the paper is considering.

bluecap said:
Is it talking about 5 dimensional spacetime?

At least one example theory given in the paper is; but I don't think the paper's general argument is limited to 5-D spacetime.

bluecap said:
I just want some comments on signal propagation in more than 4d spacetime.. any papers along this line would be appreciated.

Once again, I would strongly recommend taking the time to work through graduate level textbooks on GR and QFT first. Any other papers in this area are going to require that level of background anyway.
 

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