Since Einstein introduced his field equations and general theory of relativity, experimental evidence, at least on the cosmic scale has repeatedly supported the theory. Nevertheless, many seeking to extend the theory (Grand theories that combine relativity and quantum mechanics) or to explain gaps that have so far been attributed to TBD effects of dark matter, dark energy, etc. have failed to find anything better than GR. Recently a paper presented data from observations in our own galaxy that refutes the modified gravity theory of Moffat.
Correct me if I'm wrong, but the underlying mathematics that model the field equations of general relativity have a fundamental basis in integral calculus. Right?
To the point of my question, have any theorists explored the application of models based in fractional order calculus in consideration of gravitation field theory?