His working career started with the British Atomic Energy Agency, in Malvern, Britain, then Harwell. There they agreed with Bell about measurements on two spin 1/2 particles, as suggested by David Bohm. Moreover, by stimulating experimental tests of the deepest and most profound aspects of quantum theory, Bell’s work led to the possibility of exploring seemingly philosophical questions, such as the nature of reality, directly through experiments. He went on to do a PhD in Birmingham, specialising in nuclear physics and quantum field theory.
The first experiments that confirmed Bell's Theorem were done by John Clauser and Stuart Freedman in 1971, Clauser and Abner Shimony described the first few experiments in a 1978 review. John Stewart Bell was born in Belfast, Northern Ireland, and graduated in experimental physics at Queen's University, Belfast, in 1948. Bell's Theorem was devised by Irish physicist John Stewart Bell (1928-1990) as a means of testing whether or not particles connected through quantum entanglement communicate information faster than the speed of light. Early life
And this was just Bell’s “hobby”.
John Bell. Specifically, the theorem says that no theory of local hidden variables can account for all of the predictions of quantum mechanics.