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    Black hole Hole
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Discussion Overview

The discussion revolves around identifying and understanding solutions related to black holes within the framework of general relativity, particularly focusing on the conditions under which these solutions exist and their characteristics. The scope includes theoretical aspects of black hole metrics and the nature of vacuum solutions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the process of finding black hole solutions and questions whether any solutions of $$R_\alpha\beta=0$$ correspond to black holes.
  • Another participant suggests searching for the "Schwarzschild Solution" and "Schwarzschild Radius" as potential leads.
  • A participant notes that uncharged spherical (Schwarzschild) and rotating (Kerr) black holes are examples of vacuum solutions where $$R_{\alpha\beta} = 0$$ holds true.
  • It is pointed out that while there are black hole solutions that satisfy vacuum Einstein equations, not all vacuum solutions are black holes, with Minkowski space-time provided as a counterexample.
  • Another participant mentions that there are black hole solutions that are not vacuum solutions, such as Reissner-Nordstrom and Kerr-Newman black holes, which are classified as electrovac solutions.
  • A follow-up question is raised about how to recognize whether a metric represents a black hole and the steps involved in finding black hole solutions, particularly starting with vacuum solutions of Einstein's equations.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between vacuum solutions and black holes, indicating that while some black holes are vacuum solutions, not all vacuum solutions correspond to black holes. The discussion remains unresolved regarding the criteria for identifying black hole metrics.

Contextual Notes

There are limitations regarding the assumptions made about the nature of vacuum solutions and the definitions of black holes, which are not fully explored in the discussion.

sadegh4137
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hi
if you want to find the black hole solutions, what do you do?
has any solutions of $R_\alpha\beta=0$ a black hole?

thanks
 
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sadegh4137 said:
hi
if you want to find the black hole solutions, what do you do?
has any solutions of $$R_\alpha\beta=0$$ a black hole?

Google for "Schwarzschild Solution" and "Schwarzschild Radius".
 
Uncharged spherical (Schwarzschild) and rotating (Kerr) black holes are vacuum solutions, i.e., have $$R_{\alpha\beta} = 0.$$
 
sadegh4137 said:
has any solutions of $R_\alpha\beta=0$ a black hole?
As stated above, there are black hole solutions which solve the vacuum Einstein equations but the converse, as you have stated it, is clearly not true (a vacuum solution need not be a black hole solution). Just take the trivial solution (Minkowski space-time) as a counterexample.
 
And there are black hole solutions that are not vacuum solutions, e.g., Reissner-Nordstrom and Kerr-Newman black holes (these are electrovac solutions).
 
thanks
how you can recognize a metric is a black hole or not?
or how you can find black hole solution?
at first you find vacuum solution of Einstein equations?
and then?
 

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