What is the next easiest solution to einstein field equation after the schwarschild metric?
The Schwarzschild solution is not the easiest. Minkowski space is.
Sorry for my mistake. But what is easier after schwarschild solution? Something that involves using efe as it will help me better understand it.
This depends on what you mean by "easy" and what you wish to understand. The FRW metric is a good example which will also help you if you at some point want to study cosmology.
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