Coordinate transformations in GR, worked examples?

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Discussion Overview

The discussion centers on coordinate transformations in General Relativity (GR), specifically focusing on converting between different coordinate systems such as Schwarzschild, Gullstrand-Painleve, Boyer-Lindquist, and Doran. Participants express a desire for worked examples and practical applications of these transformations, highlighting a perceived lack of resources on the topic.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant seeks worked examples of coordinate transformations in GR, particularly between Schwarzschild and Gullstrand-Painleve, as well as Boyer-Lindquist and Doran coordinates.
  • Another participant provides links to a paper and a Wikipedia article that describe the transformation from Schwarzschild to Gullstrand-Painleve coordinates.
  • A participant mentions using specific equations from a referenced paper for their simulation but expresses uncertainty about the correctness of their approach, particularly regarding the integration of coordinate velocities.
  • There is a request for guidance on deriving transformation equations using Maxima, indicating a need for more detailed examples or tutorials.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the availability of worked examples or the clarity of existing resources. The discussion remains unresolved regarding the specific methods for performing the transformations and the adequacy of the references provided.

Contextual Notes

Participants express limitations in their understanding and application of the transformation equations, noting that some equations are quoted without derivation. There is also mention of challenges in integrating certain equations using Maxima, which may affect the clarity of the discussion.

m4r35n357
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I have read over and over in various places about coordinate transformations, and understand the theory (really!), but can't find any worked examples of actual use of the transformation equations. Does anyone know of any web references or tutorials on the subject?
To make things a little more specific, I am ultimately interested in converting between Schwarzschild <=> Gullstrand-Painleve and Boyer-Lindquist <=> Doran coordinate systems.
I find it very puzzling that such an important topic does not seem to be applied in any depth in any of the books and other sources that I have. Perhaps just looking in the wrong places . . . .
 
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This is the best I've managed to find so far, rectangular to polar, starts at about 1:37:00 . . .
(Susskind)
 
Last edited by a moderator:
Thanks for your reply Mentz114 ;)
Ah, OK (I should have mentioned this paper, sorry), equations 5, 25 and 26 do seem to address this in part, and in fact I am using precisely those equations in my "simulation", but I am not happy with it because I cannot be sure I'm doing it correctly.
They appear (to me) to cover the transformation of two of the differentials (ie. the coordinate velocities) but not the coordinates themselves. I attempted to integrate them in Maxima (trying to get a relation between the time and azimuth coordinates) but it wouldn't cooperate, just printing out the unevaluated integrals.
Going back to the "simulation", I am simply passing all the coordinates through unchanged when I go from Boyer-Lindquist to Doran, and just altering the Ut and Uphi velocities according to those equations. I just think this is too much guesswork, hence my request for references/worked examples.
So yeah, I have now fully disclosed all my sources (apologies once more), but the few equations I know about are merely quoted and not derived.
Can anyone give me any pointers how I could derive them myself (with the aid of Maxima of course)?
Also, the original request stands, are there any worked examples using any of the metrics I mentioned in the OP?
 

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