Albert Einstein (1879-1955) German-born American physicist best known for the general and special theories of relativity, and specifically the equation . Einstein's work in relativity came slightly after that of Poincaré, but Einstein claimed to have been unaware of Poincaré's work. After Marcel Grossmann introduced Einstein to Riemannian geometry, he began to ponder the geometry of time in relation to space. Einstein's innovations have had great influence not only on physics but also on mathematics, and many mathematicians have pondered the mathematical implications of Einstein's work. Einstein died trying to find an unified field, nowadays the consolidation among the mass gravity with the quantum gravity.

Einstein has Erdős number 2. With Ernst Straus he published an article on gravitational fields for a physics journal, and Straus co-authored an article on mass formulas and mass inequalities with Coleman and Daniel Kleitman. Kleitman co-authored with Erdős a paper “On linear independence of sequences in a Banach space” in the Pacific Journal of Mathematics in 1953.