
Richard Healey replied to the topic Is there an inconsistent friend? in the forum Workshop on Wigner’s Friend 2018 9 months, 4 weeks ago
Ruth,
In my view quantum theory may be applied to predict probabilities for certain magnitude claims, each restricting a dynamical variable to a Borel subset of real numbers. When quantum theory is targeted on a quantum system, a quantum state is assigned to that system in order to apply the Born rule to yield these probabilities. The magnitude…[Read more]

Richard Healey replied to the topic Is there an inconsistent friend? in the forum Workshop on Wigner’s Friend 2018 9 months, 4 weeks ago
Shan,
You focus on an important part of the third argument.
In my paper I first considered the use of QM to predict the probabilistic correlation E(a,d) in equation (29), and then appealed to Lorentz symmetry to justify the analogous equation for E(b,c). So let’s consider the argument for equation (29).If Carol had performed no measurement (C…[Read more]

Richard Healey replied to the topic Is there an inconsistent friend? in the forum Workshop on Wigner’s Friend 2018 10 months ago
The third argument makes no assumption of hidden variables. In particular, it makes no assumption concerning the actual spin values of the measured particles, either before or after the spin measurements. It assumes only that each measurement has a definite physical outcome, which may correspond to a light flashing red rather than green (for…[Read more]

Richard Healey replied to the topic Is there an inconsistent friend? in the forum Workshop on Wigner’s Friend 2018 10 months ago
As stated in the first sentence of the paragraph in which equation (31) appears, it is a central assumption of this third argument that every spin measurement performed by A,B,C and D has a definite, physical outcome. Consistent with that assumption, the measurements by A, B destroy all
 records
of C’s and D’s definite, physical outcomes. So none…[Read more]

Richard Healey replied to the topic Is there an inconsistent friend? in the forum Workshop on Wigner’s Friend 2018 10 months ago
Shan,
You say
” it seems to me that Richard’s result about the Limits of Objectivity is not valid. This result is derived from the third argument in his paper. I think the argument is based on the implicit assumption of locality, like Bell’s theorem, and one should drop this locality assumption, not the objectivity of outcomes.”Where do you thi…[Read more]

Richard Healey joined the group 2018 Workshop on Wigner’s Friend 10 months, 1 week ago



Richard Healey replied to the topic Why Bohmian theory? in the forum Bohm’s theory 4 years, 1 month ago
I think we have arrived back at the starting point of my first post on Bohmian mechanics (under a different thread—the one I emailed to you originally). There I compared the Bohmian research program after quantum theory to a Lorentzian research program after special and general relativity.
Bohm and GRW are not quantum theories but nonquantum…[Read more] 
Richard Healey replied to the topic Why Bohmian theory? in the forum Bohm’s theory 4 years, 1 month ago
Everything is fair except the last sentence. The existence of atoms is strongly supported by the evidence. The existence of a Higgs boson is also supported by the evidence, though not nearly as strongly. By contrast, the existence of Bohmian trajectories, a preferred spacetime foliation, etc. is not.

Richard Healey replied to the topic Why Bohmian theory? in the forum Bohm’s theory 4 years, 1 month ago
I don’t want to permanently and irrevocably give up on the goal of describing the world as accurately and completely as possible. But I think that goal is at least (probably) humanly unachievable, and possibly even incoherent, since it presupposes that there is some set of concepts rich enough to permit such a complete description. Pragmatism i…[Read more]

Richard Healey replied to the topic Why Bohmian theory? in the forum Bohm’s theory 4 years, 1 month ago
I started to compose a short reply to your last post, Travis, but decided that your pointed questions required a more extended response. So instead I’ve attached a piece I wrote a few years ago on what quantum theory teaches us about the concept of physical reality.
In brief, like Einstein I think of the “real” in physics as a a type of program…[Read more]

Richard Healey replied to the topic Why Bohmian theory? in the forum Bohm’s theory 4 years, 1 month ago
At the end of your first paragraph you ask “Am I at least close to right so far?”
No. In formulating or understanding quantum theory it is not necessary to appeal to a microscopic/macroscopic distinction. As a fundamental theory, quantum theory may be applied to systems of arbitrary size.
Quantum mechanics may be applied to systems of particles,…[Read more] 
Richard Healey replied to the topic Why Bohmian theory? in the forum Bohm’s theory 4 years, 1 month ago
“It would seem that the theory would then have to involve local beables, out of whose configurations facts about results of experiments would arise.”
Appearances can be deceptive!
Assume a fundamental physical theory should not involve talk of measurement or observation. (I don’t mention axioms, because I don’t think theories, fundamental or…[Read more] 
Richard Healey started the topic Comments on Bohmian mechanics in the forum Bohm’s theory 4 years, 1 month ago
Where a Bohmian theory exists that is empirically equivalent to a quantum
theory, the Bohmian theory postulates additional structures while implying
they are empirically undetectable. Pursuing the Bohmian research program
today is like pursuing a Lorentzian research program in the light of special
and general relativity. To do so is both…[Read more] 

Richard Healey replied to the topic The Assumptions of Bell’s Proof in the forum John Bell Workshop 2014 4 years, 6 months ago
I disagree that the condition that X has no influence on B can be expressed as Prob(B/X,Y)=Prob(B/Y): that condition merely expresses the inequality of two general probabilities, each of which may be used to infer a (different) chance of an outcome event being of type B (there is no unique chance of an event’s being of type B in this case—see my…[Read more]

Richard Healey replied to the topic The Assumptions of Bell’s Proof in the forum John Bell Workshop 2014 4 years, 6 months ago
Roderich, (in response to your 1898)
We can’t decide whether B is function of events on all or part of H without applying some theory. Simply observing relative frequencies of 1 in a sequence of supposedly similar sets of events can’t exclude failure of a corresponding functional relation in unobserved sets.
If we apply quantum theory, we see tha…[Read more] 
Richard Healey replied to the topic The Assumptions of Bell’s Proof in the forum John Bell Workshop 2014 4 years, 7 months ago
Dear Roderich,
In section 7 of your paper you lay out an argument as to why (L) implies (R1). Here’s why that argument fails to establish its intended conclusion.
I quote the crucial steps from your paper:
“Assume locality. Alice’s experiment takes place in a spacetime region A and Bob’s in B at spacelike separation. There is a Lorentz frame i…[Read more] 
Richard Healey replied to the topic The Assumptions of Bell’s Proof in the forum John Bell Workshop 2014 4 years, 7 months ago
Dear Roderich,
In section 7 of your paper you lay out an argument as to why (L) implies (R1). Here’s why that argument fails to establish its intended conclusion.
I quote the crucial steps from your paper:
“Assume locality. Alice’s experiment takes place in a spacetime region A and Bob’s in B at spacelike separation. There is a Lorentz frame i…[Read more]  Load More