Space-Time Curvature in General Relativity

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Discussion Overview

The discussion revolves around the nature of space-time curvature in general relativity, specifically whether it can be accurately described in terms of a Minkowski pseudo-metric. The scope includes theoretical considerations and conceptual clarifications related to the metrics used in special and general relativity.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the accuracy of claiming that space-time curvature in general relativity corresponds to a curvature of a space-time with a Minkowski pseudo-metric.
  • Another participant suggests that locally, with the appropriate coordinates, such a claim may hold true.
  • A different viewpoint asserts that special relativity (SR) employs a Minkowskian metric, while general relativity (GR) utilizes a more general Lorentzian metric, indicating that the flat Minkowskian metric is a special case of the Lorentzian metric.
  • It is noted that a manifold with either a Lorentzian or Minkowskian metric is classified as a pseudo-Riemannian manifold due to the non-positive definiteness of the metric tensor.
  • A question is raised regarding the ability to take local Lorentzian patches to form a curved space-time, while maintaining causal connections, and whether "bending" a space with a Lorentzian metric poses any issues for extending causal structures.
  • A participant references Wikipedia to highlight that a principal assumption of general relativity is that spacetime can be modeled as a Lorentzian manifold of signature (3,1).

Areas of Agreement / Disagreement

Participants express differing views on the relationship between Minkowskian and Lorentzian metrics, and whether the curvature of space-time can be accurately described in terms of a Minkowski pseudo-metric. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Some assumptions regarding the definitions of metrics and the implications of curvature on causal structures are not fully explored, leaving certain aspects of the discussion open to interpretation.

MeJennifer
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Is it accurate to claim that space-time curvature in general relativity means a curvature of a space-time with a Minkowski pseudo-metric?
 
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Locally, and with the right coodinates.
 
That doesn't sound right.

I'd suggest saying that SR is done with a Minkowskian metric, while GR has a more general space-time with a Lorentzian metric.

The flat Minkowskian metric is a special case of the more general Lorentzian metric (whcih is not necessarily flat).

A manifold with either a Lorentzian or Minkowskian metric is a pseudo-Riemannian manifold because the metric tensor is not positive definte (those pesky minus signs).
 
pervect said:
The flat Minkowskian metric is a special case of the more general Lorentzian metric (whcih is not necessarily flat).
Ok, that definition makes sense.

pervect said:
A manifold with either a Lorentzian or Minkowskian metric is a pseudo-Riemannian manifold because the metric tensor is not positive definte (those pesky minus signs).
Right, and so can we take a collection of local Lorentzian patches and form a curved space-time, which is thus as agreed upon also Lorentzian, and with maintaining a causal connection?

In other words, is "bending" a space with a Lorentzian metric unproblematic in terms of extending the causal structures?
 
Sorry!
Wikipedia:
A principal assumption of general relativity is that spacetime can be modeled as a Lorentzian manifold of signature (3,1).
 

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