Anyone here play Portal? Portal + Relativity question

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    Portal Relativity
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Discussion Overview

The discussion explores the implications of the Twin Paradox when incorporating portals, particularly in relation to relativity and time travel. Participants consider various scenarios involving portals and wormholes, examining how time dilation and simultaneity might affect the experiences of individuals in different frames of reference.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • One participant proposes a scenario where one twin remains on Earth while the other travels in a spaceship at near-light speed, suggesting that they can see and communicate through a portal.
  • Another participant raises the concept of wormholes and their potential to create time travel scenarios, referencing Kip Thorne's work on the synchronization of clocks through wormholes.
  • There is a discussion about the relativity of simultaneity, with one participant suggesting a thought experiment involving light emitters and photoplates on a moving train and a stationary platform, questioning the outcomes based on different frames of reference.
  • Some participants speculate on the consequences of returning from a relativistic journey and the potential to create a time machine using synchronized wormholes, allowing for time jumps.
  • A participant questions the observations made by individuals in different frames of reference when the spaceship returns, seeking clarity on what each observer would perceive through the portal versus directly.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the implications of portals and wormholes in the context of relativity and time travel. The discussion remains unresolved, with no consensus reached on the outcomes of the proposed scenarios.

Contextual Notes

Participants highlight limitations related to the assumptions of their scenarios, including the dependence on definitions of simultaneity and the effects of acceleration on the clocks associated with portals and wormholes. Unresolved mathematical steps and the implications of different frames of reference are also noted.

  • #61
SeventhSigma said:
Isn't all this stuff just speculation though?
Yes, it's speculative, but it's not just an arbitrary sci-fi fantasy (like "wouldn't it be cool if there was some way to make a portal connecting different places"), traversable wormholes are valid solutions to the equations of general relativity, and thus of interest to theoretical physicists exploring the consequence of the theory. Whether they are possible in the real world depends on whether the right type of "exotic matter" is possible (certain results from quantum theory like the "Casimir effect" suggest there's a good chance it is, but it's definitely not settled, see here), and also on whether there would be any process that could give rise to one in a region of space where one hadn't already existed since the Big Bang.
 
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  • #62
What would be an example of a wormhole being a "solution" to a GR equation?
 
  • #63
SeventhSigma said:
What would be an example of a wormhole being a "solution" to a GR equation?
I don't know what you mean by an "example", are you looking for the equations of a specific spacetime metric involving a wormhole? A solution just means a spacetime with a metric (describing a curved spacetime) and a matter field that satisfies the Einstein field equations (dealing with the relation between matter distribution and spacetime curvature) at every point in the spacetime. Anyway, the detailed equations for one such solution can be found in this paper, for example (the author also has a full textbook on the subject titled Lorentzian Wormholes)
 
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