In the 1920’s, after centuries of dispute over whether light is a wave or particles, Bohr devised the compromise that holds today, that they are complementary views so both are true, and nothing better has been found since:
“…nobody has found anything else which is consistent yet, so when you refer to the Copenhagen interpretation of the mechanics what you really mean is quantum mechanics.” (Davies & Brown, 1999), p71.
The result was a don’t ask, don’t tell policy, where light can be a wave when we don’t look, as long as it is particles when we do, and physics can apply particle or wave equations as convenient. In no pond do rippling waves act like particles, and on no table do billiard-ball particles act like waves, but Bohr managed to sell the big lie that light is a wavicle. As Gell-Mann said in his 1976 Nobel Prize speech:
“Niels Bohr brainwashed a whole generation of physicists into believing that the problem (of the interpretation of quantum mechanics) had been solved fifty years ago.”
Figure 3.4 shows the options available. Physical realism, that only physical things exist, doesn’t allow waves that don’t follow its laws, so there is a physical world but no quantum world (Figure 3.4a). If so, how are physicists using quantum waves to predict atomic events different from witchdoctors that call on spirits to heal people, as both invoke what is imaginary?
To avoid this, Copenhagen dualism was that the quantum world existed for physicist’s equations, but otherwise it didn’t, which in effect made both the physical world and the quantum world exist somehow (Figure 3.4b). But that a quantum world existed for the convenience of physics was an admission of failure, not a theory advance (Audretsch, 2004), p14. Like Descartes’ mind-body dualism, it was a mystical marriage of convenience between incompatible domains, accepted by those who want to believe it. It began fake physics, where imaginary things cause real events if the equations work. Yet even as he publicly made the quantum world exist in some way, in private he denied that it existed at all. He wanted the best of both worlds but knew they were incompatible.
The alternative to both physical realism and Copenhagen dualism is quantum realism, that physical events are a subset of quantum events (Figure 3.4c). Now the one reality is quantum not physical, as it generates the physical world within it, so classical mechanics is a subset of quantum mechanics. What then are the properties of this reality, or as Wheeler put it, how come the quantum?
Note: A “big lie” is a statement so outrageous that people think it must be right or it wouldn’t be said.