Coordinate transformations in GR, worked examples?

In summary, the conversation discusses the topic of coordinate transformations and the lack of worked examples or references on the subject. The speakers mention their interest in converting between different coordinate systems and provide links to papers and articles that address this topic. They also discuss their attempts at deriving and integrating equations using Maxima and request any additional resources or pointers on how to do so.
  • #1
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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  • #2
This is the best I've managed to find so far, rectangular to polar, starts at about 1:37:00 . . .
(Susskind)
 
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  • #4
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?
 

1. What is a coordinate transformation in general relativity (GR)?

A coordinate transformation in GR is a mathematical operation that allows us to express the same physical phenomenon or event in different coordinate systems. This is necessary because in GR, the geometry of spacetime is curved, so different observers may use different coordinate systems to describe the same event.

2. How does a coordinate transformation affect the measurement of distances and time intervals in GR?

A coordinate transformation can change the measurement of distances and time intervals in GR. This is because the curvature of spacetime means that the concept of "straight lines" and "equal time intervals" are no longer absolute. As a result, the measurements of distances and time intervals may differ between different coordinate systems.

3. Can you provide a real-life example of a coordinate transformation in GR?

Yes, a common example of a coordinate transformation in GR is the conversion between Cartesian coordinates (x, y, z) and spherical coordinates (r, θ, φ). In this transformation, the same point in space is described using different coordinates, and the equations for measuring distances and angles change accordingly.

4. How do you perform a coordinate transformation in GR?

To perform a coordinate transformation in GR, you need to use the equations of general relativity, which describe the relationship between coordinates and physical quantities like distances and time intervals. These equations can be solved using mathematical techniques such as tensor calculus to obtain the transformed coordinates.

5. Why are worked examples important in understanding coordinate transformations in GR?

Worked examples are important in understanding coordinate transformations in GR because they provide concrete, step-by-step demonstrations of how the equations of GR are applied to different scenarios. They also allow us to see the effects of coordinate transformations on physical quantities, which can be difficult to visualize with just theoretical explanations.

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