Jim Baggott in Physics World:
“Surely, after 62 years, we should have an exact formulation of some serious part of quantum mechanics?” wrote the eminent Northern Irish physicist John Bell in the opening salvo of his Physics World article, “Against ‘measurement’ ”. Published in August 1990 just two months before his untimely death at the age of 62, Bell’s article outlined his concerns. As he further explained, “By ‘exact’ I do not of course mean ‘exactly true’. I mean only that the theory should be fully formulated in mathematical terms, with nothing left to the discretion of the theoretical physicist…until workable approximations are needed in applications.”
Although Bell spent the majority of his career as a theoretical particle physicist and worked on accelerator design at the CERN lab in Geneva, today he is best known for his contributions to deep, foundational questions that probe the meaning of quantum mechanics. Nearly a century after it was first formulated, there is still no consensus among physicists on how the theory should be interpreted. “I think I can safely say that nobody understands quantum mechanics,” Richard Feynman famously declared – a rather extraordinary admission for a foundational theory that underpins much of our understanding of modern physics.
Indeed, the debate about the interpretation of quantum mechanics, which began in 1927, continues to this day.