What is the source of curvature in an accelerating frame?

Click For Summary

Discussion Overview

The discussion centers on the nature of curvature in accelerating frames, particularly in relation to the Ricci and Riemann tensors in vacuum space. Participants explore the implications of these tensors in the context of general relativity, the equivalence principle, and coordinate transformations between curved and flat spacetime.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants question whether an accelerating frame in vacuum space has a non-zero Ricci or Riemann tensor, with one asserting that both are zero.
  • There is a discussion about the nature of coordinate transformations in curved spacetime, with a participant noting the infinite possibilities of such transformations.
  • One participant argues that the Ricci tensor being zero implies a flat space, yet questions the implications for accelerating frame coordinates.
  • Another participant emphasizes that "flat" is a property of spacetime, not coordinates, and suggests that the Ricci tensor can be computed from Rindler coordinates in flat spacetime.
  • Concerns are raised about how observers in accelerating frames can explain gravity under the equivalence principle, with some clarifying that gravitational coordinate acceleration does not require intrinsic spacetime curvature.
  • Participants discuss the implications of the equivalence principle, noting that it states local effects of acceleration and gravity are equivalent, but does not equate the two directly.
  • One participant presents a graphical analogy to illustrate the concepts of flat and curved spacetime, while others question the accuracy of these representations.
  • There is a mathematical inquiry into whether a vanishing Ricci tensor implies an inertial frame and whether ignoring all second derivatives of the metric equates to ignoring tidal effects.
  • Another participant asserts that local inertial frames can be constructed regardless of the Ricci tensor's value.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the Ricci and Riemann tensors in accelerating frames, with no consensus reached on whether an accelerating frame can be considered flat or how the equivalence principle applies in this context. Multiple competing views remain regarding the interpretation of curvature and coordinate systems.

Contextual Notes

Limitations include unresolved mathematical steps regarding the implications of the Ricci tensor and the nature of spacetime in accelerating frames. The discussion also highlights the dependence on definitions of flatness and the properties of spacetime versus coordinate systems.

  • #31
PeterDonis said:
I'll respond to this with another question: how can ##\nabla^2 \Phi## be nonzero when ##\rho## is zero, which it is everywhere outside the source? Doesn't that violate Poisson's equation?

(Hint: you might want to check the actual definition of the Laplacian operator ##\nabla^2## in spherical coordinates.)
This is cool, yes it should violate it unless ##\nabla^2\Phi## is zero which it is according to the definition of Lapalacisn operator. Thank you.
 

Similar threads

  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 8 ·
Replies
8
Views
1K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 22 ·
Replies
22
Views
2K
  • · Replies 3 ·
Replies
3
Views
929
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 3 ·
Replies
3
Views
942
  • · Replies 36 ·
2
Replies
36
Views
5K