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Matthew Leifer joined the group
2018 Workshop on Wigner’s Friend 4 years, 7 months ago
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Matthew Leifer replied to the topic Does the psi-epistemic view really solve the measurement problem? in the forum
2016 International Workshop on Quantum Observers 7 years, 4 months ago
jiri soucek,
I am somewhat sympathetic to the view that quantum theory should be understood in terms of some sort of non-Kolmogorovian probability theory. However, there are a couple of problems with this.
First, it is not just since 2008 that this option has existed. There are currently a few dozen competing generalized probability theories…[Read more]
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Matthew Leifer replied to the topic Does the psi-epistemic view really solve the measurement problem? in the forum
2016 International Workshop on Quantum Observers 7 years, 4 months ago
Shan,
“In fact, the writing of this paper is mainly motivated by your words in your review paper. You said, “A straightforward resolution of the collapse of the wavefunction, the measurement problem, Schrodinger’s cat
and friends is one of the main advantages of psi-epistemic interpretations…. The measurement problem is not so much resolved by ps…[Read more] -
Matthew Leifer replied to the topic Does the psi-epistemic view really solve the measurement problem? in the forum
2016 International Workshop on Quantum Observers 7 years, 4 months ago
Shan,
We have had so many discussions about this now that I am beginning to think that you are being deliberately obtuse, and trying to court controversy where there ought to be none.
Let me first note that not all ontological models solve the measurement problem, psi-epistemic or not. Some do and some don’t. Since Bohmian mechanics can be fit…[Read more]
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Matthew Leifer replied to the topic What's wrong with the wave function? in the forum Meaning of the wave function 7 years, 11 months ago
A couple of comments:
“But epistemic construals of the wave function face formidable ob-
stacles, most notably a number of no-go theorems (Bell 1964; Kochen and
Specker 1967; Pusey, Barrett and Rudolph 2012).”What is it about Bell and Kochen-Specker that you think an obstacle to epistemic construals of the wave function? Those theorems make no…[Read more]
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Matthew Leifer replied to the topic A PBR-like argument for psi-ontology in terms of protective measurements in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
One big objection to your argument is that, if true, it would imply that classical probability distributions are also properties of individual systems. The reason is that we can do the whole protective measurement scheme for Gaussian states using only Gaussian operations. Quantum mechanics with only Gaussian states and operations is equivalent…[Read more]
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Matthew Leifer replied to the topic Why protective measurement does not establish the reality of the wave function in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
I think it is also probably possible to derive some sort of mathematical equivalence between the two types of protective measurement, i.e. to convert an adiabatic scheme into a Zeno scheme and vice versa. This may have been discussed in the literature but I am not sure. If so, it would probably be possible to adapt the Alice/Bob/Charlie story to…[Read more]
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Matthew Leifer replied to the topic Why protective measurement does not establish the reality of the wave function in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
To be clear, there are two versions of protective measurement discussed in the literature. The “Zeno” version in which weak measurements are intersperesed with projective measurements, as discussed in Matt’s notes, and the adiabatic version referred to by Shan. For the adiabatic version, we do have a model of how a Gaussian state, e.g. the…[Read more]
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Matthew Leifer replied to the topic The Quantum Wave Function as Property and as Pre-probability in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
Bob,
This is not to do with the status of the wavefunction specifically, but what I have always disliked about your approach to consistent histories is a consequence of the single framework rule.
Different frameworks may contain some projectors in common, which is precisely what happens in Bell-Kochen-Specker experiments. Any inferences between…[Read more]
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Matthew Leifer replied to the topic The Quantum Wave Function as Property and as Pre-probability in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
Matt #1010,
Perhaps I can help Bob out by offering an example. It also happens in Spekkens’ toy theory. There, the set of pure states is isomorphic to the set of outcomes of maximally informative measurements. The former are epistemic and the latter represent ontic properties of the system.
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Matthew Leifer replied to the topic Epistemic Roots of the Schrodinger Equation in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
Hi Ken,
“As a final note; the PBR theorem examines the status of the wavefunction at *preparation*, and determines it is ontic. And yet few people have examined models in which the wavefunction makes an ontic-to-epistemic transition (where the probability overlap between states grows with time).”
I don’t understand this comment. PBR employs…[Read more]
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Matthew Leifer replied to the topic Primitive Ontology in a Nutshell in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
OK, yes that is roughly what I meant.
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Matthew Leifer replied to the topic Primitive Ontology in a Nutshell in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
Shan, I should also comment that piping the audio from Skype into Google Hangouts, which is what I assume you are doing, does not work very well. Your audio is OK, but Valia and Richard were quite difficult to hear.
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Matthew Leifer replied to the topic Primitive Ontology in a Nutshell in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
OK, since I have been outed as a lurker by Shan, let me ask how you would describe the role of the non-primitive ontology in a theory that does not support a division into states at a given time and dynamics? You previously suggested that the role of the non primitive ontology is to compute how the primitive ontology evolves in time, but what…[Read more]
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Matthew Leifer replied to the topic The meaning of the wave function. in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
Robert,
I think you are clearly a psi-epistemicist. For my purposes, this just means that you do not view the quantum state as an intrinsic property of an individual system. Whether you are neo-Copenhagen is a trickier question, which we have debated before over email. On my view, two key components of the Copenhagen interpretation are:
– The…[Read more]
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Matthew Leifer replied to the topic The meaning of the wave function. in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
Richard & Ken,
Perhaps the distinction between QBism and Richard’s position is similar to the difference between objective and subjective Bayesianism, or between the earlier “logical” theories of probability and subjective Bayesianism. In subjective Bayesianism, probabilities represent degrees of belief and they are not to be analysed into…[Read more]
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Matthew Leifer replied to the topic The meaning of the wave function. in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
Regarding this:
“This restricts such an agent’s access to information and so would make it necessary for him/her/it to aim for an ideal epistemic state that took account of all and only information about events in his/her/its backward light cone in forming beliefs about matters not so accessible.”
I wonder what your view of an object like “the w…[Read more]
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Matthew Leifer replied to the topic The meaning of the wave function. in the forum
First iWorkshop on the Meaning of the Wave Function 8 years, 7 months ago
I think there will be a lot of debate about the significance of protective measurements later in the workshop, so let’s perhaps put that to one side for now. I have a few comments more specific to Richard’s paper.
Firstly, I think it is a little bit unfortunate that the modern debate about the meaning of the wavefunction uses the terms “ontic”…[Read more]
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Matthew Leifer joined the group
Meaning of the Wave Function 8 years, 8 months ago