If measurements of quantum phenomena can show results that are truly random wouldn't it be possible to establish a macroscale-dependence on such a non-statistical result and thereby introduce randomness and an interruption of determinism - if it exists - into the classical realm?

This is similar to the Schrödinger's Cat thought experiment, about which Schrödinger wrote:

It is typical of these cases that an indeterminacy originally restricted to the atomic domain becomes transformed into macroscopic indeterminacy, which can then be resolved by direct observation.

Some speculate that "determinism can emerge from underlying indeterminism (via the law of large numbers)" and that "the universe could be conceived of as having alternating layers of causality and chaos".

Here it says:

According to several standard interpretations of quantum mechanics, microscopic phenomena are objectively random. That is, in an experiment that controls all causally relevant parameters, some aspects of the outcome still vary randomly. For example, if a single unstable atom is placed in a controlled environment, it cannot be predicted how long it will take for the atom to decay—only the probability of decay in a given time. Thus, quantum mechanics does not specify the outcome of individual experiments but only the probabilities. Hidden variable theories reject the view that nature contains irreducible randomness: such theories posit that in the processes that appear random, properties with a certain statistical distribution are at work behind the scenes, determining the outcome in each case.

And here:

This debate is relevant because it is easy to imagine specific situations in which the arrival of an electron at a screen at a certain point and time would trigger one event, whereas its arrival at another point would trigger an entirely different event (e.g. see Schrödinger's cat - a thought experiment used as part of a deeper debate).

  • $\begingroup$ yes, you can en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory $\endgroup$
    – user65081
    Oct 1, 2019 at 22:16
  • $\begingroup$ Can you please explain what do you mean by "true randomness" and how can you test it? Also, what do you mean by " macroscale-dependence on such a non-statistical result"? $\endgroup$
    – Andrei
    Oct 2, 2019 at 6:06
  • $\begingroup$ With that I mean actual randomness, not lack of knowledge of initial conditions. There is no consensus that this exists / is possible in our Universe and in quantum mechanics. The question has a condition that it is possible and measurable. So as long as this is a valid option - and I'm also interested in supportive and contrary arguments and tests - it's an assumption for the rest of the question. With macroscale-dependence I mean making a choice in our realm dependent on a non-statistical measurement result that is supposed to be random. Maybe just making it classically observable is enough. $\endgroup$
    – mYnDstrEAm
    Oct 2, 2019 at 9:04
  • $\begingroup$ Since we do not know how to draw the line between what is classical and what is quantum, it is difficult to see how this question can even be framed rigorously. $\endgroup$ Oct 2, 2019 at 11:16
  • $\begingroup$ I don't think a clear-cut distinction would be needed or is possible: it's just terms used to describe the actual nature of reality. The question is about the transformation of a phenomena from the quantum realm (nothing close to the macroscopic realm but non-statistical on the level of e.g. a single photon) to the classical (again nothing close to the quantum realm but a non-statistical decision on the level of e.g. man-made decisions). $\endgroup$
    – mYnDstrEAm
    Oct 2, 2019 at 11:36

1 Answer 1


I guess that you could, in principle, make a stochastic classical theory that is able to reproduce QM, but, as proven by EPR, such a theory needs to be non-local. In an EPR-Bohm test, for example, if you want the result of the first measurement to be "truly" random you need to accept that this measurement instantly "forces" the distant particle to get the oposite spin.


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