Shwartzschild coordinate system

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Discussion Overview

The discussion revolves around the possibility of transforming Schwarzschild coordinate components of time and distance into a flat Minkowski spacetime. Participants explore the implications of such transformations and the inherent differences between the two spacetimes.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that there are no direct transformation equations between Schwarzschild coordinates and Minkowski spacetime due to their fundamentally different manifolds.
  • Others propose that while a global transformation is impossible, local approximations to Minkowski coordinates can be made over small regions of spacetime.
  • One participant draws an analogy between the transformation of curved coordinates (latitude and longitude) on a sphere and Cartesian coordinates in a plane, suggesting similar limitations apply to the Schwarzschild and Minkowski spacetimes.
  • It is noted that each spacetime has inherent quantities that are invariant under coordinate transformations, with geodesics in Minkowski spacetime behaving differently from those in Schwarzschild spacetime.
  • Participants discuss curvature scalars, mentioning that the Ricci scalar is zero in Schwarzschild spacetime, while the Kretschmann scalar is the simplest nonzero curvature scalar in this context.

Areas of Agreement / Disagreement

Participants generally agree that a direct transformation is impossible, but there are differing views on the nature of local approximations and the implications of curvature invariants.

Contextual Notes

Limitations include the dependence on the specific definitions of curvature and the conditions under which local approximations may hold. The discussion does not resolve the complexities of equivalence under coordinate transformations.

omidj
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TL;DR
Transformation equations from Schwarzschild coordinate and metric to Minkowski space time
Is there any direct transformation equations from schwarzschild coordinate components of time and distance to a flat Minkowsky space time?
These basis vectors seem to be capable of producing the Shwarzschild metric:
et=√(1-rs/r)cosh(ct) eT +√(1-rs/r)sinh(ct) eR
er=(1/√(1-rs/r))sinh(ct) eT +(1/√(1-rs/r))cosh(ct) eR
(et&er for Schwarzschild and eT&eR for Minkowsky) But when Jacobian matrix is derived, the problem emerges ...
 
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They are different manifolds so there is not a coordinate transform between them. Of course locally you can always find coordinates that approximate Minkowski to first order.
 
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omidj said:
Is there any direct transformation equations from schwarzschild coordinate components of time and distance to a flat Minkowsky space time?
It cannot be done, for about the same reason that we cannot find a transformation between latitude and longitude on the curved surface of the earth and cartesian x-y coordinates on a euclidean plane.

We can of course ignore the curvature completely and use ordinary Minkowski polar coordinates as an approximation valid over sufficiently small regions of spacetime, analogous to the way that we treat the surface of the earth as flat across a sufficiently small area.
 
omidj said:
Is there any direct transformation equations from schwarzschild coordinate components of time and distance to a flat Minkowsky space time?
Please use LaTeX.

As it was already said, such a transformation is impossible. Each spacetime comes with its inherent quantities that are invariant under coordinate transformations. Geodesics in Minkowski spacetime (straight lines) can intersect each other once at most. In Schwarzschild spacetime, they may do so many times (for example: circular orbits in opposite directions). No coordinate transformation can change that.
The question of equivalence up to a coordinate transformation can be a complex challenge in the general case. Sometime it is sufficient to consider a few curvature scalars. Scalar fields are invariant under coordinate transformations, like the Ricci scalar ##R=R^\mu{}_\mu## . For the example given by @Nugatory in post #3, the 2D Euclidean plane has ##R=0## , while the unit sphere has ##R=2## , which proves the claim that they are fundamentally distinct.

Edit: corrected error
 
Last edited:
PeterDonis said:
Note that in Schwarzschild spacetime, which is a vacuum solution, this scalar is zero. The simplest nonzero curvature scalar in Schwarzschild spacetime is the Kretschmann scalar:

https://en.wikipedia.org/wiki/Kretschmann_scalar
Yes. I should have mentioned it in #4.
 

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