John Horgan in Scientific American:
In August 1992 I visited David Bohm at his home in a London suburb. His skin was alarmingly pale, especially in contrast to his purplish lips and dark, wiry hair. His frame, sinking into a large armchair, seemed limp, languorous, and at the same time suffused with nervous energy. One hand cupped the top of his head, the other gripped an armrest. His fingers, long and blue-veined, with tapered, yellow nails, were splayed. He was recovering, he said, from a heart attack.
Bohm’s wife brought us tea and biscuits and vanished. Bohm spoke haltingly at first, but gradually the words came faster, in a low, urgent monotone. His mouth was apparently dry, because he kept smacking his lips. Occasionally, after making an observation that amused him, he pulled his lips back from his teeth in a semblance of a smile. He also had the disconcerting habit of pausing every few sentences and saying, “Is that clear?” or simply, “Hmmm?” I was often so hopelessly befuddled that I just smiled and nodded. But Bohm could be bracingly clear, too. Like an exotic subatomic particle, he oscillated in and out of focus.
Born and raised in the U.S., Bohm left in 1951, the height of anti-communist hysteria, after refusing to answer questions from a Congressional committee about whether he or anyone he knew was a communist. After stays in Brazil and Israel, he settled in England. Bohm was a scientific dissident too. He rebelled against the dominant interpretation of quantum mechanics, the so-called Copenhagen interpretation promulgated by Danish physicist Niels Bohr.
Bohm began questioning the Copenhagen interpretation in the late 1940s while writing a book on quantum mechanics. According to the Copenhagen interpretation, a quantum entity such as an electron has no definite existence apart from our observation of it. We cannot say with certainty whether it is either a wave or a particle. The interpretation also rejects the possibility that the seemingly probabilistic behavior of quantum systems stems from underlying, deterministic mechanisms.