AN OVERVIEW OF SIX DIFFERENT APPROACHES TO QUANTUM MECHANICS
John R. Gribbin (born 1946) is a British science writer, astrophysicist, and a visiting fellow in astronomy at the University of Sussex. In 1974, Gribbin also published (and later regretted) 'The Jupiter Effect,' which predicted that the alignment of the planets in March 1982 would cause gravitational effects that would trigger earthquakes in the San Andreas fault, possibly wiping out Los Angeles and its suburbs.
He wrote in the Preface to this 2019 book, “I thought it might be worth offering an agnostic overview of some of the main interpretations of quantum physics. All of them are crazy, compared with common sense… but in this world, crazy does not necessarily mean wrong… I have chosen six examples… I have my own views on their relative merits… Before offering those interpretations, though, I ought to make it clear just what we are trying to interpret.” (Pg. x-xi)
He explains, “Although the jumping-off point for Bell’s Theorem was an attempt to understand quantum physics… there results do not apply only to quantum physics. They apply to the world---the Universe. Whether or not you think that quantum physics might one day be replaced by a description of how the world works, this will not change things. The experiments show that local reality does not apply to the Universe. Whether you choose to find solace in keeping reality and accepting non-locality, or in keeping locality and rejecting reality, is a matter of personal preference, as we shall see.” (Pg. 17-18)
He notes, “When an atom absorbs light, an electron disappears from one orbit and appears in one further out from the nucleus of the atom. But it does not MOVE from one orbit to the other. First it is here; then it is there. This is known as a quantum leap… Schrödinger intended his wave mechanics to explain what happens during the leap, but it didn’t and he said: ‘If all this damned quantum jumping were really here to stay, I should be sorry I ever got involved with quantum theory.’” (Pg. 24)
He states, “In essence, the Copenhagen Interpretation says that a quantum entity does not have a certain property---any property---until it is measured. Which raises all kinds of questions about what constitutes a measurement. Does human intelligence have to be involved?... It was this kind of concern that led Schrödinger to come up with his famous puzzle about the cat locked in a room… Is the cat … in a superposition of states, both dead and alive, until someone opens the door of the rom to look in?” (Pg. 31-32)
He recounts, “De Broglie spelled out the pilot wave argument in detail… at the Como meeting. Looking back with the benefit of hindsight, in 1987, John Bell wrote in this book ‘Speakable and Unspeakable in Quantum Mechanics’: ‘this idea seems to natural and simple, to resolve the wave-particle dilemma in such a clear and ordinary way, that it is a great mystery to me that is was so generally ignored.’ Actually, this is not such a great mystery… [Niels] Bohr, aided… by Wolfgang Pauli, poured scorn on the idea and crushed the more diffident de Broglie, more by the force of their personalities and … reputations than by the validity of their arguments. The second reason de Broglie’s idea got trashed, was von Neumann’s incorrect ‘proof’ that such theories were impossible. De Broglie gave up any attempt to promote his idea, and it was … completely forgotten by physicists…” (Pg. 38)
He states, “it’s worth mentioning a surprising comment on [David] Bohm’s theory from someone who might have been expected to endorse it. Even though Einstein had been the instigator of Bohm’s attempt to find an alternative to the Copenhagen Interpretation, on 12 May 1952, he wrote to Max Born: ‘Have you notices that Bohm believes (as de Broglie did, by the way, 25 years ago) that he is able to interpret the quantum theory in deterministic form? That way seems too cheap to me.’ Nobody is quite sure what he meant by this, but it highlights the confusion surrounding all of the interpretations of quantum mechanics.” (Pg. 44)
Turning to the ‘Many World Interpretation’ [MWI] of Hugh Everett III, he records, “[the idea] as enthusiastically promoted by Bryce DeWitt… who wrote: ‘every quantum transition taking place in every star, in every galaxy, in every remote corner of the universe is spitting our local world on Earth into myriad copies of itself.’ This became too much for [John] Wheeler, who backtracked from his original endorsement of the MWI, and … said: ‘I have reluctantly had to give up my support of that point of view in the end---because I am afraid it carries too great a load of metaphysical baggage.” (Pg. 48)
He states, “So what actually happens when a ‘pure’ quantum entity interacts with the outside world and ‘docoheres’? It doesn’t get LESS entangled, but MORE… there is no such thing as a ‘pure’ quantum system separated from the world outside… but an entangled system of both, a superposition of everything that has interacted with the original particle and everything it has ever interacted with, and everything that that everything has ever interacted with or has ever come into contact with. ‘Decoherence’ actually involves linking everything in the entire world---the Universe---into a single quantum system. We no longer detect the quantumness of the once-isolated particle because it is mixed-up with everything else.” (Pg. 59)
He argues, “This also pulls the rug from under one of the philosophical objections to the Copenhagen Interpretation. Taken at face value, the CI says that ‘nothing is real’ unless it is being observed… So, said opponents of the idea, does the Moon exist when nobody is looking at it[?]… Did it exist, in this sense, before there was life on Earth? Bohr had no satisfactory answer to this. The Decoherence Interpretation has---photons from the microwave background radiation, let alone those of sunlight, are more than adequate to produce decoherence and make the Moon ‘real.’” (Pg. 60-61)
He explains, “Quantum mechanics, says [Lee] Smolin, applies to small subsystems of the Universe, which come in many copies… but macroscopic systems, like cats and people, have no copies anywhere in the Universe, so they are not affected by the copying process that involves interacting quantum beables. They have nothing to interact with, in this sense. This has some interesting implications. First, the Universe must be finite… Secondly,… Smolin can also derive the laws of classical mechanics… as an approximation of quantum mechanics. But he suspects that quantum mechanics is itself an approximate version of some deeper description of the Universe… and he goes to far as to suggest that genuine faster-than-light signaling might occur if that is the case… If all this sound bizarre, Smolin has a reminder for us. At one time, people found it impossible to believe that the Sun influenced … the planets.” (Pg. 72-73)
He outlines the Transactional Interpretation: “It should be no surprise that the way the Transactional Interpretation deals with time differs from common sense, because the Transactional Interpretation explicitly includes the effects of relativity theory. The Copenhagen Interpretation, by contrast, treats time in the classical… way, and this is at the heart of the inconsistencies in any attempt to explain the results of quantum experiments measuring Bell’s inequality in terms of the Copenhagen interpretation.” (Pg. 83)
He concludes, “All the Solaces are equally good; all of them are equally bad. At least that means you are free to choose whichever one gives you most comfort, and ignore the rest.” (Pg. 84)
This brief book will interest those looking for overview of major interpretations of quantum mechanics.