https://blogs.scientificamerican.com/observations/beware-of-theories-of-everything/ > By 1931, Kurt Gödel had proven his second incompleteness theorem, which states that a formal logical system cannot prove itself consistent. This theorem throws cold water on the ultimate ability to prove “theories of everything,” which have become fashionable in theoretical physics. It implies that any scientific theory is incomplete. 
 > Galileo Galilei went beyond the limitations of pure logic and argued that any physical theory claiming to describe reality must also make predictions that stand up to the scrutiny of experiments. He found experimentally, for example, that heavy objects do not accelerate faster than light objects under the influence of gravity, as previously thought. This result laid the foundation for Albert Einstein’s later realization that gravity is not a force but the curvature of spacetime that all test objects respond to in the same way.