Quantum_ Einstein, Bohr and the Great Debate About the Nature of Reality - Manjit Kumar [183]
As Einstein's influence waned, Bohr's grew. With missionaries like Heisenberg and Pauli spreading the message among their own flocks, the Copenhagen interpretation became synonymous with quantum mechanics. When he was a student in the 1960s, John Clauser was often told that Einstein and Schrödinger 'had become senile' and their opinions on matters quantum could not be trusted.28 'This gossip was repeated to me by a large number of well-known physicists from many different prestigious institutions', he recalled years after becoming the first to test Bell's inequality in 1972. In stark contrast, Bohr was deemed to possess almost supernatural powers of reasoning and intuition. Some have even suggested that while others needed to perform calculations, Bohr did not.29 Clauser recalled that during his student days 'open inquiry into the wonders and peculiarities of quantum mechanics' that went beyond the Copenhagen interpretation was 'virtually prohibited by the existence of various religious stigmas and social pressures, that taken together, amounted to an evangelical crusade against such thinking'.30 But there were unbelievers prepared to challenge the Copenhagen orthodoxy. One of them was Hugh Everett III.
When Einstein died in April 1955, Everett was 24 and studying for his master's degree at Princeton University. Two years later he obtained a PhD with a thesis entitled 'On the Foundations of Quantum Mechanics' in which he demonstrated that it was possible to treat each and every possible outcome of a quantum experiment as actually existing in a real world. According to Everett, for Schrödinger's cat trapped in its box this would mean that the moment the box was opened the universe would divide, leaving one universe in which the cat was dead and another in which it was still alive.
Everett called his interpretation the 'relative state formulation of quantum mechanics' and showed that his assumption that all quantum possibilities exist led to the same quantum mechanical predictions for the results of experiments as the Copenhagen interpretation.
Everett published his alternative in July 1957 with an accompanying note from his supervisor, the distinguished Princeton physicist John Wheeler. It was his very first paper and it went virtually unnoticed for more than a decade. By then disillusioned by the lack of interest, Everett had already left academia and was working for the Pentagon, applying game theory to strategic war planning.
'There is no question that there is an unseen world', the American film director Woody Allen once said. 'The problem is how far is it from midtown and how late is it open?'31 Unlike Allen, most physicists balked at the implications of accepting an infinite number of co-existing parallel alternative realities in which every conceivable outcome of every possible experimental result is realised. Sadly, Everett, who died of a heart attack aged 51 in 1982, did not live to see the 'many worlds interpretation', as it became known, taken seriously by quantum cosmologists as they struggled to explain the mystery of how the universe came into being. The many worlds interpretation allowed them to circumvent a problem to which the Copenhagen interpretation had no answer – what act of observation could possibly bring about the collapse of the wave function of the entire universe?
The Copenhagen interpretation requires an observer outside the universe to observe it, but since there is none – leaving God aside – the universe