Time travel and cosmic strings

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Discussion Overview

The discussion centers on the concept of cosmic strings as introduced by Stephen Hawking in relation to the possibility of time travel to the past. Participants explore the theoretical underpinnings of cosmic strings, their properties, and their implications for time travel, drawing on both theoretical physics and speculative ideas.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on the concept of cosmic strings and their relation to time travel as discussed by Hawking.
  • Another participant describes cosmic strings as theoretical entities with immense tension and energy, suggesting that their mass and energy distribution could affect space curvature, potentially allowing for time travel scenarios.
  • A different participant references the "van Stockum cylinder" as a theoretical model that could enable backward time travel, although they express uncertainty about the length of cosmic strings compared to this model.
  • A link to further reading on cosmic strings and topological defects is provided for additional context.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and uncertainty regarding cosmic strings and their implications for time travel. There is no consensus on the nature of cosmic strings or their feasibility in the context of time travel.

Contextual Notes

The discussion includes speculative elements about the existence and properties of cosmic strings, which remain theoretical and not empirically validated. The relationship between cosmic strings and time travel is not fully resolved, with participants presenting different models and interpretations.

Hercule Poirot
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In his book "the universe in a nutshell", stephen hawkings is discussing the possiblity of time travel to the past (ch. 5 How to protect the past). He introducted the concept of cosmic strings to explain that. would anyone here could explain this concept and it's relation to time travel?

Thanks,
 
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What cosmic strings exactly are I don't know, but the tension on them is huge and the energy is because of that. They are strings, so that means that their energy and mass are distributed along a line, apparently that does something to the space curvature opening possibilities if they were to slide along each other creating other types of energy that way (like heat). They are apparently predicted to having been caused by the big bang.

Cosmic strings are *very* theoretical, but they seem to be allowed to exist by quantummechanics and relativity. In everything that we've seen before (like all predicted particles for example) everything that was predicted by a (for now assumed) valid theory really exists.
So we might conclude that because they are allowed to exist, they must. Argument comes also from Hawking.
 
The relation to time travel is that it's been shown that a hypothetical dense, rotating cylinder of infinite length would allow a traveler moving near it to go backwards in time--google "van stokum cylinder" to find more info on this. But I don't think cosmic strings would actually be infinite in length.
 

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