Dear Richard,

Perhaps I understand better now the root of our disagreement. It seems to have something to do with whether the definition of locality refers to actions of an agent on one side having consequences on the other side, or whether it refers to events on one side having consequences on the other side, where events may include random…[Read more]

Dear Bob,

Yes, let’s agree to disagree. Thank you for the discussion.

All the best, Roderich

Dear Richard, (in response to your #1901)

I agree that “we can’t decide whether B is a function of events on all or part of H without applying some theory” if “theory” means laws governing a possible reality (i.e., what I called a “scenario” in my paper). Quantum theory is often understood as not talking about reality but only about empirical…[Read more]

Dear Bob, (at #1900)

Yes, it would good to find out what exactly we disagree about. So let me answer your questions about my position. By “English properties” I did not mean macroscopic properties. In your example, I assume that S is 1-dimensional. I agree that with “cat is alive” is associated a (high-dimensional) subspace A of the Hilbert space…[Read more]

Dear Bob,

Thank you for your replies #1860 and 1861. There are two relevant meanings of the word “property”: let me call them “English property” (the ordinary meaning of “property” in English) and “quantum property.” An English property of a system is something that a system either has or has not, while a “quantum property” of a system is a…[Read more]

Dear Richard (at #1859 and 1894),

I like that you point specifically to the step in the reasoning that you are objecting to. That helps for a good discussion.

I see that the word “pre-determines” has connotations that are irrelevant to the argument. For my purposes, “x pre-determines y” just means “y is a function of x.” It is not necessary to…[Read more]

Dear Richard,

Indeed one might suspect that statements about probability, or even fixity, must be relativized in the way you suggest. So let me go through the reasoning in more detail. The state-of-affairs (i.e., the “real, factual situation,” the “beables”) on that hypersurface includes Alice’s outcome, so it pre-determines Bob’s outcome (as Bob…[Read more]

Dear Bob,

Let me first address the Carol-Donald issue. I was, in fact, paying attention to the distinction you emphasize; let me elaborate some more. Let n_k be the unit vector in the direction in which Carol has prepared the spin of particle k. She predicts that if one were to make a Stern-Gerlach experiment on particle k in the direction n_k,…[Read more]

Thank you to all of the commentators for your remarks!

To Dieter at 1674:

You may be surprised but I completely agree with you that Everett’s many-worlds proposal is a realist theory. In my paper, I considered the conditions (R1) through (R4) for their potential relevance to Bell’s theorem, not for categorizing interpretations of quantum…[Read more]