Not mentioned · Public domain

Weeks after Einstein published general relativity in 1915, Schwarzschild produced the theory's first exact solution — while serving as an artillery officer on the Russian front. His solution described the spacetime around a single, non-rotating mass and gave physics the Schwarzschild radius, the boundary now understood as a black hole's event horizon, decades before anyone believed such objects could actually exist. He died the following year of an autoimmune disease contracted at the front, at 42.