John Bell (1928 - 1990)
Bell's theorem is there is test the quantum theory against Einstein's notion of local realism, the idea that only the immediately surroundings of an object can effect that object.
The experiment is tests whether or not the real world satisfies local realism.
The experiment has its origins in debate between Einstein and other pioneers of Quantum mechanics, principally, Niels Bohr.
In 1964, Bell, after a year leave from CERN, that he spent at Stanford, Bell wrote, "On the Einstein-Podolsky-Rosen paradox."