Bell, John (1928-1990)

Northern Irish physicist who in 1964 discovered a paradoxical aspect of quantum theory: two particles that were once connected are always afterwards interconnected even if they become widely separated. As well as investigating fundamental problems in theoretical physics, Bell contributed to the design of particle accelerators.

Bell worked for 30 years at CERN, the European research laboratory near Geneva, Switzerland. He put forward mathematical criteria that had to be obeyed if the connection required by quantum theory really existed. In the early 1980s, a French team tested Bell's criteria, and a connection between widely separated particles was detected.