Adapting Schwarzschild Metric for Nonzero Λ

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Discussion Overview

The discussion centers on the adaptation of the Schwarzschild metric to incorporate a nonzero cosmological constant (Λ). Participants explore the implications of modifying existing metrics, particularly focusing on the Schwarzschild-de Sitter solution and its characteristics in relation to stress-energy tensors and black hole properties.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the feasibility of modifying the Schwarzschild metric to maintain a zero stress-energy tensor while accounting for a nonzero cosmological constant.
  • Another participant identifies the Schwarzschild-de Sitter spacetime as a relevant solution, noting significant differences such as a maximum mass for black holes.
  • A participant clarifies that while modifications are necessary when introducing a nonzero cosmological constant, the Schwarzschild-de Sitter solution retains similarities to the Schwarzschild metric, with specific adjustments in the metric components.
  • A later reply acknowledges a previous misunderstanding regarding the stress-energy tensor and introduces the idea of a metric that reflects the vacuum energy density contributing to the cosmological constant.
  • One participant asserts that the Schwarzschild-de Sitter metric meets the conditions discussed and encompasses a Schwarzschild black hole.

Areas of Agreement / Disagreement

Participants generally agree that the Schwarzschild-de Sitter solution is relevant to the discussion, but there is no consensus on the extent to which fundamental properties of the Schwarzschild metric can be preserved when adapting for a nonzero cosmological constant.

Contextual Notes

Limitations include the dependence on specific assumptions about the nature of the cosmological constant and the ambient energy density, as well as unresolved details regarding the mathematical modifications needed to achieve the desired properties.

Sciencemaster
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TL;DR
The Schwarzschild metric is designed with a cosmological constant in mind. Would it be feasible to make some modifications to it that would make it apply in a spacetime with a nonzero Λ?
So, there are a fair amount of metrics designed with a zero value for the cosmological constant in mind. I was wondering if there was some method to modify metrics to account for a nonzero cosmological constant. Say, for instance, the Schwarzschild metric due to its relative simplicity. A feature of the metric is that it has a stress-energy tensor of 0 due to both the ricci tensor and scalar curvature going to 0. However, this doesn't happen if the cosmological constant is nonzero. So, would there be a way to modify a metric to account for a nonzero cosmological constant while keeping fundamental features intact--in this case, the 0 stress energy tensor and general form of the Schwarzschild metric? I tried multiplying by a constant as well as a few other minor modifications, and none of them gave a SET of 0. So, would it be feasible to make some modification to a metric designed for Λ=0 in order for it to apply when Λ is nonzero while still keeping similar basic properties?
 
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That's Schwarzschild-deSitter spacetime, if I understand what you're trying to do.

I don't know about "keeping similar basic properties". There are some quite significant differences, such as a maximum mass for a black hole.
 
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Sciencemaster said:
would there be a way to modify a metric to account for a nonzero cosmological constant while keeping fundamental features intact--in this case, the 0 stress energy tensor and general form of the Schwarzschild metric?
Of course you can't keep everything else exactly the same when you add a nonzero cosmological constant. But the Schwarzschild-de Sitter solution, which @Ibix mentioned, is what you get when you assume spherical symmetry, a nonzero cosmological constant, and no other stress-energy present. If you look it up, you will see that its metric is quite similar to the Schwarzschild metric; the only difference (at least in the coordinates that correspond to standard Schwarzschild coordinates) is an extra term in ##\Lambda## in ##g_{rr}## and ##g_{tt}##.
 
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First off, I want to add that I made a mistake. I said something along the lines of, 'keeping the Schwarzschild metric's property of a 0 SET. However, I neglected the ambient energy density in the universe that contributes to the nonzero cosmological constant. So...yeah, I was thinking about a metric that gave $$T_{00}=\frac{\rho_{vacuum}}{c^2}$$. Ignoring that, thanks for suggesting the Schwarzschild-de Sitter, that definitely helps and might be close enough to what I'm looking for!
 
Sciencemaster said:
Schwarzschild-de Sitter, that definitely helps and might be close enough to what I'm looking for!
It is what you are looking for; it is the unique metric that satisfies the condition you give in post #4 and also contains a Schwarzschild black hole.
 

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