[ExI] Is quantum mechanics is deterministic or stochastic?

[BillK]

In Giulio's current discussion, John Clark claimed "the quantum wave
function is completely deterministic but, because we can only observe
a very small part of it, things seem random to us, so we must resort
to probability in our predictions."
-------------

This claim is much disputed by quantum theorists. Every experiment has
supported the randomness of quantum mechanics. While emotionally
appealing (e.g. Einstein), the search for support of 'hidden-variables
theory' has so far failed.

Bell's theorem would appear to prove many hidden-variable theories to
be impossible.
See: <https://en.wikipedia.org/wiki/Hidden-variable_theory>
<https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics>

Ethan Siegel has a recent article on this very subject.
<https://bigthink.com/starts-with-a-bang/quantum-spookiness/>

Quotes:
STARTS WITH A BANG — NOVEMBER 16, 2021

How the best alternative to “quantum spookiness” failed

Many still cling to the idea that we live in a deterministic Universe,
despite the nature of quantum physics. Now, the "least spooky"
interpretation no longer works.
The idea that two quanta could be instantaneously entangled with one
another, even across large distances, is often talked about as the
spookiest part of quantum physics. If reality were fundamentally
deterministic and were governed by hidden variables, this spookiness
could be removed. Unfortunately, attempts to do away with this type of
quantum weirdness have all failed.

KEY TAKEAWAYS
Until the discovery of radioactivity and quantum physics, every
particle and interaction was thought to obey completely deterministic
equations. Quantum mechanics can only yield an indeterminate
probability distribution of outcomes. It cannot tell you what comes
next. The leading deterministic interpretation, involving hidden
variables, is called Bohmian mechanics. Its only distinct prediction
was just falsified.
-----------------

Fascinating article!

BillK