Solving the Spherically Symmetric Einstein Equation

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SUMMARY

The discussion centers on simplifying the Einstein Field Equations (EFE) for spherically symmetric mass-energy distributions. It confirms that in this scenario, the metric can be expressed with only two unknown functions, significantly reducing complexity compared to the general case with ten unknowns. The recommended resources include worksheets from Pomona College and General Relativity notes from the University of Chicago, particularly chapters 24 and 25, which discuss the Schwarzschild solution and its implications. The simplification process involves selecting coordinates that make the metric diagonal and using the areal radius as one of the coordinates.

PREREQUISITES
  • Understanding of Einstein Field Equations (EFE)
  • Familiarity with General Relativity concepts
  • Knowledge of metric tensors and their components
  • Basic grasp of differential geometry
NEXT STEPS
  • Study the Schwarzschild solution in detail from General Relativity notes
  • Explore Birkhoff's theorem and its implications for spherically symmetric solutions
  • Learn about stress-energy tensors and their role in the EFE
  • Investigate coordinate transformations in the context of General Relativity
USEFUL FOR

Students and researchers in theoretical physics, particularly those focusing on General Relativity and gravitational theories. This discussion is beneficial for anyone looking to deepen their understanding of spherically symmetric solutions in the context of the Einstein Field Equations.

Tomas Vencl
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TL;DR
When suppose only spherically symmetric distribution of mass-energy, how it simpify the Einstein equation ?
Can be Einstein equation rewrited into some simpler form, when suppose only spherically symmetric (but not necessarily stationary) distribution of mass-energy ?
If yes, is there some source to learn more about it ?
Thank you.
edit: by simpler form I mean something with rather expressed derivatives, than more compact form (if this makes sense)
 
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Tomas Vencl said:
Can be Einstein equation rewrited into some simpler form, when suppose only spherically symmetric (but not necessarily stationary) distribution of mass-energy ?

Yes. For the spherically symmetric case, there are only two unknown functions of the coordinates in the metric (a general metric with no symmetry has ten unknown functions of the coordinates, one for each of the independent metric components). The most common way of treating this case is to choose coordinates such that the metric is diagonal and the areal radius ##r## (given by ##r = \sqrt{A / 4 \pi}##, where ##A## is the radius of the 2-sphere containing the event in spacetime whose coordinates one is evaluating) is one of the coordinates. The general form of the metric with these assumptions, along with the significant components of the Einstein tensor, is given in this Insights article:

https://www.physicsforums.com/insights/short-proof-birkhoffs-theorem/

The article only considers the actual solution of the EFE for the vacuum case; but one can easily generalize what is done there to the non-vacuum case by simply putting the appropriate stress-energy tensor components (as functions of ##t## and ##r##) on the RHS of the equations.
 
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Thank you both, I will look at the links.
 

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