Einstein's Formulation of Tensor Equation: Was He Lucky?

[barong]

I understand that all physical laws essentially codify mathematically observed behavior. Newton codified Kepler and Brahe data, for example. Quantum Mechanics codifies observed particle behavior at relatively low speeds, etc. But Einstein had no empirical data to work from… So, I do not understand how it was possible for him to “invent” something that ended up working empirically… I know he was a genius, but was he also “simply” lucky?

 

[atyy]

Einstein was a bit lucky. He had two pieces of data. (1) Newtonian gravity was inconsistent with special relativity (Maxwell's equations and the absence of the aether), so a new theory of gravity was needed that was consistent with special relativity and that reduced to Newtonian gravity in the appropriate limit. (2) The perihelion precession of mercury appeared inconsistent with Newtonian gravity, so if the new theory of gravity could explain that, that would be a point in its favour.

At that time, (at least) two theories of gravity fulfilling (1) were known: Nordstrom's scalar theory, and Einstein's tensor theory. However, Nordstrom's theory was not consistent with the observed perihelion precession, but Einstein's was.