The end of year 2019 was marked for me by a sudden revelation about the entanglement (aka EPR) “paradox”. Here is my confession, first. For a long time I had been thinking that the “superposition or entanglement paradox” consisted in the following:
Two particles (possessing a certain probabilistic characteristic such as a spin) originating from the same source were entangled, i.e. connected by, say, one being in phase alpha, while the other one in opposite phase (180-alpha). Then the particles were be sent into different directions of travel and remained entangled and what’s important their alpha parameter would still be unknown. Then at some point in time and space one of the particles would have been measured, and say found to be equal to 1 (I suppose we can use binary encoding without loss of generality). Now, here comes my misinterpretation: Then at the very same moment in time the other particle would be disentangled and its value would be exactly opposite, i.e. equal to 0. Therefore the paradox (in my interpretation) was as follows: (1) the state resolution in time is simultaneous for both particles, i.e. while forcing the measurement of the first particle we immediately have the measurement of the second particle; and (2) the state resolution on terms of value of one particle would completely determine that of the value of the second particle.
My problem was not in understanding why (2) was true. That was quite clear to me for a long time, especially after my discussions with experts like Professor Werner Hofer, who explained to me, a non-expert on quantum theory, that both particles, once entangled, would retain their phases and in that respect would remain information-wise connected. My problem was in accepting and understanding (1), which I my view violated temporal causality and no action at distance. I could not accept the fact that there would be no delay between the initiated measurement of the first particle and simultaneous resolution of the second particle. The reason for my conundrum was that I am a firm believer in causality of related events in time, and I could not accept (1).
But, thanks again to good old Werner (!), with whom we talked a few days before Christmas 2019, I realised that there is actually no paradox at all here. What actually happens is that – there is no issue (1) involved! The resolution of the second particle in fact can happen concurrently or independently of that of particle one! And the whole pathos of the EPR was only in part (2). This gave me an enormous relief and peace of mind needed for the coming festive season. The expected asynchrony and delay-insensitivity of the physical world had been restored! And, as far as part (2) is concerned, that was a trivial thing to me – this is purely a combinatorial (non-sequential in terms of automata) issue of one value being statically opposite to the other value – what’s the big deal !?
Now, what annoyed me in all this conundrum, well, obviously my own naivety and my inaccurate reading about the EPR paradox. On the other hand, I think that the lack of clarity in separating the issues of timing from value, i.e. when and what, that is quite symptomatic of the 20th century mathematical physics, involving complex quantum mechanical constructions, is what makes engineering-minded people like me – who expect both these issues to be properly addressed – confused and misled!