--Von Neumann QM is deterministic except during "measurements." Modern view/hope is measurements really do not exist. If so then as a result, everything is completely deterministic. However it sure seems like there are measurements and nondeterminism, e.g. radioactive decay. That allegedly is an illusion. (So Asimov had it exactly wrong, QM excludes the possibility of NONdeterminism.) What happens is, you only perceive part of the universe. The whole ball of wax is deterministic, but since you only perceive part it seems nondeterministic and seems to involve "measurements."

From: Dan Asimov <dasimov@earthlink.net> To: math-fun <math-fun@mailman.xmission.com> Subject: Re: [math-fun] free will Message-ID: <70F0E5F5-28AB-467D-91F3-5CDC403859DE@earthlink.net> Content-Type: text/plain; charset=us-ascii

These two things ("free will" and "determined by causes I can't perceive") are not almost the same, but instead are almost opposites. Of course, "determined by causes I can perceive" would also exclude free will. Ultimately, "free will" per se is precisely the opposite of "determinism".

Speaking of determinism, can someone please clarify a confusion I've had about the consequences of quantum mechanics:

1) I used to believe in determinism, but then learned that QM implied some things happened ultimately by chance with no underlying mechanism.

2) Then I believed there must be hidden variables until I heard of Bell's Theorem, which is said to prove the non-existence of hidden variables in QM.

3) Then I heard that Bell's Theorem is valid only if non-locality is excluded.

QUESTION: Does QM exclude the possibility of determinism? Is some kind of non-locality consistent with known physics?

--Dan