Analogue of Lorentz transformation in General Relativity.

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Discussion Overview

The discussion centers on the existence of an analogue to the Lorentz transformation within the framework of General Relativity, particularly in the context of curved spacetime. Participants explore the implications of transformations between different frames of reference, specifically freely-falling frames, and the potential complexities involved in such transformations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether an analogue to the Lorentz transformation exists in General Relativity, suggesting that parallel transport might be relevant but could complicate the analogy.
  • Another participant notes that the Lorentz transformation connects a specific class of frames in Special Relativity, while in General Relativity, the only special frames are freely-falling frames. They propose that a transformation might connect two such frames, contingent on the details of the spacetime, but express uncertainty about its existence.
  • A different viewpoint suggests that rather than an analogue, there is a generalization where the length of the "world line" remains invariant across different frames of reference.
  • One participant inquires about the possibility of a general transformation between coordinates of freely-falling frames, specifically in the context of Painleve-Gullstrand coordinates.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of an analogue to the Lorentz transformation in General Relativity. Multiple competing views are presented regarding the nature of transformations between frames and the implications of freely-falling frames.

Contextual Notes

The discussion highlights the complexity of transformations in curved spacetime and the potential limitations of existing theories in describing these transformations. There is an acknowledgment of the dependence on specific coordinate systems and the nature of the spacetime being considered.

arroy_0205
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Can anybody tell me if there is anything analogous to Lorentz transformation in General Relativity (ie, in curved space)? If there is then what are the corresponding group generators and what is the corresponding algebra? I just wondered this question while reading about Lorentz group and I am not very if such analogy will exist in curved space. But may be using the concept of parallel transport such analogies may be made but that will be complicated.
 
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As you know, the LT connects a special class of frames in SR. It seems the only possible set of special frames in GR are the freely-falling frames. Each FF observer can construct a local SR frame whose spatial axes are local null geodesics (in reality this frame may be limited in size by the local field). If we know the details of the space-time, it ought to be possible to devise a transformation that connects two such frames, but I don't know what it is or even if it exists.

[edit] Of course there's no reason whatever why two different FFFs should be inertial wrt to each other, so whatever transformation connects them will not look much like the LT.
 
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Not an "analogue" but a "generalization". And that is that that the length of the "world line" is the same from any frame of reference.
 
HallsofIvy,

Is there a general transformation between freely-falling frame coords ?

[tex]x_{\mu} \rightarrow x'_{\mu} = f(x_{\mu})[/tex]

I'm trying to work something out in Painleve-Gullstrand co-ords.

M
 
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