Gravitation theories can use metrics {metric theory} or be non-metric. A ten-parameter general metric theory {parametrized post-Newtonian formalism} can model all metric gravitation theories, which then differ only in parameter values.
parameters
The ten parameters model: How mass causes space curvature. How gravity-field superposition is non-linear. If space has preferred reference frame, or all spatial directions are equivalent. If all four space-time components have momentum conservation. If distant galaxies affect local interactions. If general metric theory does or does not include gravitational-radiation effects or other gravity-strength changes.
types
Metric theories include general theory of relativity, scalar-tensor theories, vector-tensor theories, tensor-tensor theories, conformally flat theories, stratified theories, and quasi-linear theories.
non-metric
Non-metric gravitation theories violate completeness, consistency, relativity, and/or Newtonian limit.
Physical Sciences>Physics>Relativity>General Relativity>Theory
5-Physics-Relativity-General Relativity-Theory
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Date Modified: 2022.0224