God does not play dice
Probably the most bizarre (I’m still tossing up the double-slit experiment and measurement) prediction quantum mechanics makes is entanglement. As we know entanglement occurs when particles such as photons interact physically and then become separated; the type of interaction is such that each resulting member of a pair is properly described by the same quantum mechanical state, which is indefinite in terms of important factors such as position, momentum, spin, polarization, etc.
Entanglement was of course not always used as further proof of quantum theory. In 1935 Einstein who was not convinced that quantum theory was complete and thought he had finally devised a construct (EPR Paper) that would show quantum theory for what it was – in his opinion so bizarre, so counter to all logical views and experience that it would have to be incomplete. When Einstein died in 1955 he was still very much convinced that quantum mechanics offered at best an incomplete theory. And so with his passing it remained to be seen how, when and if he would be proved right.
I first read John Bell’s 1964 paper “On The Einstein Podolsky Rosen Paradox” (follow link below for the article) some 15 years ago. At the time I didn’t quite grasp the historical, and more importantly it’s profound implications in helping decide, despite the weirdness of entanglement, to be indeed accurate. For this obscure paper written by a relatively unknown Irish physicist presenting a method to break the deadlock between Bohr’s Copenhagen interpretations of quantum mechanics (that quantum mechanics does not yield a description of an objective reality) and Einstein’s views. Through the work of John Clauser and others entanglement has been shown to be a principle that underpins our understanding of the universe and our perception of reality.
So the [new] contemporary basic physical theory differs profoundly from the classical physical world on the important matter of how the consciousness of human agents enters into the structure of empirical phenomena (the measurement problem). The new principles contradict the older idea that local mechanical processes alone can account for the structure of all observed empirical data. If the neural basis of behaviour can generally posits brain mechanisms that explain psychologically described phenomena – quantum mechanically based causal mechanisms frameworks have to be understood in order to achieve an adequate theory of the neurophysiology of volitionally directed activity.