Today, collapse theories, together with Bohm’s theory and Everett’s theory, are widely regarded as three main realistic alternatives to standard quantum mechanics. However, there have been controversies on the origin, ontology and models of wavefunction collapse. The main purpose of this online workshop is to highlight the existing debates and address the controversies. Another purpose of this workshop is to get some constructive inputs to the forthcoming volume Collapse of the Wave Function: Models, Origin and Ontology (CUP, 2018). The list of contributors includes Daniel Bedingham, Dorje C. Brody, Lajos Diosi, MichaëlAndreas Esfeld, Roman Frigg, Ivette Fuentes, Lane Hughston, Shan Gao, GianCarlo Ghirardi, Nicolas Gisin, Adrian Kent, Peter Lewis, Nicholas Maxwell, Wayne Myrvold, Elias Okon, Oreste Nicrosini, Roland Omnès, Philip Pearle, Roger Penrose, Alberto Rimini, Tejinder P. Singh, Lee Smolin, Daniel Sudarsky, and Roderich Tumulka.
Workshop Date: Tuesday, 30 May, 2017 to Friday, June 30, 2017


Ruth Kastner replied to the topic The Relativistic Transactional Interpretation is a Collapse Theory in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 2 months ago
Just an update that this paper has been accepted in this journal.

Ruth Kastner started the topic The Relativistic Transactional Interpretation is a Collapse Theory in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 5 months ago
Reasons to consider the Relativistic Transactional Interpretation, which allows for collapse without changing the basic quantum theory (and remedies shortcomings in the original TI):
On the Status of the Measurement Problem: Recalling the Relativistic Transactional Interpretation


Wayne C. Myrvold started the topic Ontology for Collapse Theories in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 6 months ago
In this chapter, I will discuss what it takes for a dynamical collapse theory to provide a reasonable description of the actual world. I will start with discussions of what is required, in general, of the ontology of a physical theory, and then apply it to the quantum case. One issue of interest is whether a collapse theory can be a quantum state…[Read more]

Ilja Schmelzer replied to the topic Three arguments for the reality of wavefunction collapse in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 7 months ago
Dear Shan,
I would object to your claim (paper) about a problem of dBB with the Born rule. The point is that it is not the relative positions of the Bohm particles which matters, but their absolute positions.
Of course, what humans perceive as a measurement result would have to be, in principle, relative. But simply including the positions…[Read more]


Michael Devereux started the topic Reduction of the atomic wavefunction within the SternGerlach magnetic field in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 8 months ago
Reduction of the atomic wavefunction within the SternGerlach magnetic field.
Michael Devereux (Los Alamos National Lavoratory, retired)
It’s easy to show that the quantum wavefunction of an atom traversing a SternGerlach magnet is immediately reduced to a single spindirection eigenfunction when a magnetic field quantum is transferred to t…[Read more]



Robert Griffiths replied to the topic Three arguments for the reality of wavefunction collapse in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 8 months ago
5 June 2017
Dear Shan,
First me suggest you take a look at my contribution to this workshop under the heading of “Wavefunction Collapse Not Needed”, as then some of the following comments will make more sense. In particular, note the representation of physical properties by means of Hilbert subspaces or the corresponding projectors. This idea…[Read more]

Robert Griffiths started the topic Wavefunction Collapse Not Needed in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 8 months ago
There is no need for wavefunction collapse in standard quantum mechanics. Probabilities assigned by the Born rule are sufficient. In the case of measurements of a simple sort, Kraus operators can be used to generate a “collapsed state” of the measured system, but this is fully justified using the Born rule and conditional probabilities; no sep…[Read more]

editor started the topic On the Status of Primitive Ontology in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 8 months ago
My argument here is that, in the case of spontaneous collapse theories, primitive ontology is redundant, in the sense that the structures exhibited by the primitive ontologies that allow them to solve the problems facing spontaneous collapse theories are also present in the wave function. But redundancy is not nonexistence; indeed, the fact that…[Read more]

Robert Griffiths replied to the topic Collapse. What else? in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 8 months ago
Dear Nicolas,
I appreciate your including some references [19] to older work on the consistent histories (CH) approach, at the beginning of your discussion of Bohmian mechanics (BM) in Sec. III. That could, unfortunately, give the reader the mistaken impression that CH has something to do with BM, whereas the two approaches are quite different.…[Read more]


Arthur Jabs started the topic reduction and measurement in quantum mechanics in the forum 2017 International Workshop: Collapse of the Wave Function 2 years, 9 months ago
A conjecture concerning determinism, reduction, and measurement in quantum mechanics∗
Arthur Jabs
Alumnus, Technical University Berlin. Voßstr. 9, 10117 Berlin, Germany arthur.jabs@alumni.tuberlin.de
(29 May 2017)
Abstract. Determinism is established in quantum mechanics by tracing the probabilities in the Born rules back to the absolute (o…[Read more] 

Ruth Kastner posted an update in the group 2017 International Workshop: Collapse of the Wave Function 2 years, 9 months ago
I hope that the editors of the mentioned volume will consider nonunitary collapse in the transactional picture. I realize that this is not considered a ‘mainstream’ approach, but there are ample peerreviewed publications on it with no refutations that I’m aware of. A recent peerreviewed publication on the advantages of collapse for…[Read more]


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