General Relativity and Cosmology

TLDR: The general theory of relativity is considered to be Albert Einstein's masterpiece in theoretical physics as mentioned in this paper, where scientists like Hendrik Lorentz and Henri Poincare worked in parallel, motivated by the unsolved physical problems existing at the beginning of the twentieth century, such as motion with respect to the aether and the negative result of the Michelson-Morley experiment.

Abstract: The general theory of relativity is considered to be Albert Einstein’s masterpiece in theoretical physics. In contrast with special relativity, where scientists like Hendrik Lorentz and Henri Poincare worked in parallel, motivated by the unsolved physical problems existing at the beginning of the twentieth century (for instance, motion with respect to the aether and the negative result of the Michelson–Morley experiment), there was no such motivation for general relativity. With the exception of an anomaly in the precession of Mercury’s orbit, the Newtonian theory of gravitation did not manifest symptoms of obsolescence.