The reason I’m late to the party is the oddity of my time zone (India), not that I want to have the last word!

To my mind, the wave function is a computing “machine” with inputs and outputs. (I’m happy to note that some of you would agree with this.) Pop in (a) the outcomes of the relevant measurements that were made, (b) the times when they were…[Read more]

Dear Lee,

Sorry it’s taken me so long to get back to this thread… I was trying to keep up with the schedule of the other talks. But *this* is my favorite topic.. 🙂

When you write:

” … there is an objective asymmetry between what we can know or give truth values to in the past, as opposed to the future. One reason out of several I am…[Read more]

Hi Matt,

Thanks for this! I look forward to reading your final paper.

Yes, I agree that “the operational argument does not depend in any way on what the protective measurement scheme tells Bob to do.”

But in your note, you say: “But since protective measurement uses exactly the same resources, how can it lead to a radically different conclusion…[Read more]

Correct ‘no’ to ‘know’ in the last line of #1144. RBG

Dear Lee,

My answer to the Dowker and Kent criticism is that the fact that there are alternative frameworks in no way invalidates the quasiclassical framework of Gell-Mann and Hartle. This has not convinced either of them. A not-too-lengthy discussion of things from my present perspective is in “The New Quantum Logic,” Found. Phys. 44 (June,…[Read more]

Dear Bob,

Many thanks for your comments. My first response is that I don’t think that the REF has the issue with retrodiction you mention, but I’ll look into it.

I haven’t thought through your consistent histories framework carefully in many years so I will take your invitation to do so again. At one time there was an argument by Dowker and…[Read more]

Dear Shan,

Before the final bell rings let me express what I am sure is the universal belief of the participants: We all appreciate the hard work you have done
in organizing things for this workshop. Thanks a great deal!

Dear Richard, re #1139

I advocate as the principled way the Single Framework Rule; at least that seems to allow in enough things for the physicist to do physics, and not so many that one ends up with insoluble paradoxes. The result, by the way, is
a satisfactory ability to do retrodiction, but without retrocausality, though some criticis of the…[Read more]

Dear Richard, re your #1134

I would agree that statements about what the measurement actually measured, when they are microscopic properties, need to be treated with caution and put in the proper framework or consistent family, and I think the experimentalists are correct (without being able to supply a full explanation of why they are correct)…[Read more]

Ken,

I don’t want to throw stuff out: I just want to make sure there is a principled way of letting in enough stuff to answer Bob’s question as to what quantum probabilities are probabilities of: i.e. without using any of Bell’s proscribed words such as ‘measurement’. If there is a principled and consistent way of allowing more stuff in, I’d be…[Read more]

To Bob at #1134,

I think my last remark about the position of a detected photon is a first step toward addressing your second aspect of the measurement problem. Some experimenters talk as if the results of their measurements simply reveal the value the measured magnitude already had (e.g. where it was). I think they can get away with this talk…[Read more]

Richard… Okay, but then I don’t see why you would want to restrict m(x,t) to only being meaningful at certain t’s. After all, m(x,t) would include the entire past history of the entities (such as one of Bob’s consistent history paths through an interferometer), and restricting this to m(x,t_m) where t_m is the measurement times would throw…[Read more]

To Ken at #1133,

I agree: but I wouldn’t want to do that. I don’t want to restrict claims about positions and such to contexts that we ordinarily think of as measurements (like opening the box). Claims about positions are both significant and (sometimes) true whenever a system’s state is environmentally decohered in position basis. Of course it’s…[Read more]

To Richard #1129:

… where the application of quantum theory presupposes that exactly one outcome will occur.

Exactly! This is why I tend to think of the measurement problem as a pseudoproblem.

Dear Richard,

I think your #1129 truncates the measurement problem. Not only do we want
the pointer to stop shaking, we want to learn something about the PREVIOUS state of the particle from the pointer’s later position. That’s how experimental physics is carried out, and most obviously so when the apparatus eats up the particle so it is not…[Read more]