
Ruth Kastner replied to the topic Is there an inconsistent friend? in the forum Workshop on Wigner’s Friend 2018 3 years, 7 months ago
Thanks, Richard for this clarification.
Of course, I think your analysis can also perfectly well apply to an ontic role for the quantum state.
Under an epistemic view of the quantum state, then it seems to me that if one posits that measurements really do have definite outcomes, then an implicit hidden variable view must be lurking in the…[Read more] 
Ruth Kastner replied to the topic Is there an inconsistent friend? in the forum Workshop on Wigner’s Friend 2018 3 years, 7 months ago
This is an interesting situation: assessments of the bearing and validity of the FR proof greatly depend on what quantum theory itself is taken to be. For example, Editor has referred to two different forms of QT:
(1) QT with collapse postulate — call it “QTCP”
(2) QT without collapse postulate — call it “QTNCP”
…and has noted, based on…[Read more] 
Ruth Kastner replied to the topic Is there an inconsistent friend? in the forum Workshop on Wigner’s Friend 2018 3 years, 7 months ago
I would just comment here that Brukner’s formulation of the measurement problem presupposes an epistemic interpretation of the quantum state relative to a particular observer. So his analysis and conclusions do not apply to cases in which the quantum state ontologically refers. In particular, he concludes that facts are necessarily…[Read more]

Ruth Kastner started the topic How we avoid getting to the Wigner's Friend situation in the first place in the forum Workshop on Wigner’s Friend 2018 3 years, 7 months ago
The Wigner’s Friend scenario was created to amplify the measurement problem as illustrated by Schrodinger’s Cat. We don’t encounter a Wigner’s Friend dilemma in the first place if we have a means of delineating, in physical terms, what constitutes ‘measurement’ (where that is described by von Neumann’s Process 1 nonunitary transition)…[Read more]

Ruth Kastner replied to the topic Is there an inconsistent friend? in the forum Workshop on Wigner’s Friend 2018 3 years, 7 months ago
Dear Editor: Should I start a new topic to address the measurement problem, which is what is being illustrated by the Wigner’s Friends scenario? In particular, we don’t encounter a Wigner’s Friend dilemma in the first place if we have a means of delineating, in physical terms, what constitutes ‘measurement’ (where that is described by von…[Read more]

Ruth Kastner posted an update in the group 2018 Workshop on Wigner’s Friend 3 years, 7 months ago
May I add as a relevant reference:
Kastner, R. E. On the Status of the Measurement Problem: Recalling the Relativistic Transactional Interpretation
International Journal of Quantum Foundations, 2017,
Volume 4, Issue 1, pages 128141
I would just note that RTI is not subject to the recent ‘nogo’ proofs since it does not assert that quantum states are universally applicable; rather it has a natural limiting criterion for the applicability of quantum states. It particular, neither the Geiger counter nor the cat nor Wigner nor his friend (understood as spacetimelocatable obj…[Read more]


Ruth Kastner joined the group 2018 Workshop on Wigner’s Friend 3 years, 7 months ago

Ruth Kastner started the topic TI: Derivation of the Born Rule for Radiative Processes in the forum Retrocausal theories 4 years ago
The Transactional Interpretation involves advanced field states and is therefore considered a form of a ‘retrocausal’ interpretation, although in the relativistic development of TI (RTI), the advanced states (as well as the triggering retarded states) are complex objects and are subempirical (i.e., not spacetime processes). It is only the…[Read more]

Ruth Kastner started the topic The Transactional Interpretation is a Collapse Theory in the forum Collapse theories 4 years ago
It is not widely recognized that the Transactional Interpretation (TI) is a collapse theory; however, it is one that does not make ad hoc changes to the Schrodinger equation. Collapse is accounted for in TI by taking into account absorber response as a physical process (in the socalled ‘absorber theory’ of fields). Absorber response provides the…[Read more]

Ruth Kastner wrote a new post, Topic for 2018 Int'l Workshop on Quantum Foundations 4 years ago
I would like to discuss the Relativistic Transactional Interpretation, specifically the explicit derivation of the Born Rule for radiative processes as presented in my recent paper with John Cramer (https://arxiv.org/abs/1711.04501).
It appears clear that TI and RTI provide a physical account of measurement as well as a physical derivation of the Born Rule. Previous objections to TI (such as that of Maudlin) have been unambiguously resolved and/or nullified (e.g., https://arxiv.org/abs/1610.04609). Thus, TI is still perfectly viable and provides longsought solutions to pressing problems in quantum theory regarding the need for a physically grounded definition of ‘measurement’ and the source of the Born Rule (as well as a solution to the consistency problems for QFT as reflected in Haag’s theorem, http://www.ijqf.org/archives/2004). Curiously, however, TI is still not generally recognized as among the ‘mainstream’ approaches. I look forward to discussing with other IJQF members why that might be. Is it the apparent “action at a distance” of the directaction theory that is offputting? Is it because both Wheeler and Feynman abandoned their theory (though Wheeler was later advocating it again in 2003)? Comments welcome.

Ruth Kastner wrote a new post, Submission: Quantifying Absorption in the Transactional Interpretation 4 years, 3 months ago
R. E. Kastner, John G. Cramer 3 Feb. 2018
Abstract: The Transactional Interpretation offers a solution to the measurement problem by identifying specific physical conditions precipitating the nonunitary […]

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Ruth Kastner wrote a new post, New Submission: Reply to Marchildon: absorption and nonunitarity remain welldefined in the Relativistic Transactional Interpretation 4 years, 5 months ago
I rebut some erroneous statements and attempt to clear up some misunderstandings in a recent set of critical remarks by Marchildon regarding the Relativistic Transactional Interpretation (RTI) in this Journal, showing that his negative conclusions regarding the transactional model are illfounded.
Paper link here: Reply to LM IJQF4

Ruth Kastner posted an update 4 years, 5 months ago
At the request of D. Kalamidas I am posting his proposal for FTL signaling which appears in Pramana here: http://rdcu.be/AZYC
I think it cannot work because it requires a welldefined time order for spacelike separated events, in which the measurement outcomes are assumed to occur for the signaler prior to the recipient, contrary to relativity…[Read more] 
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 4 years, 5 months ago
Just an update that this paper has been accepted in this journal.

Ruth Kastner posted an update 4 years, 6 months ago
I recently posted on the arxiv a paper written with John G. Cramer, refuting claims that absorption is not welldefined in the transactional interpretation. Comments welcome. https://arxiv.org/abs/1711.04501
It should be noted that TI is not in the class of theories termed ‘spontaneous collapse theories’ (even though it has spontaneous col…[Read more] 
Ruth Kastner started the topic The Relativistic Transactional Interpretation is a Collapse Theory in the forum 2017 International Workshop: Collapse of the Wave Function 4 years, 8 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

Ruth Kastner wrote a new post, On the Status of the Measurement Problem: Recalling the Relativistic Transactional Interpretation 4 years, 8 months ago
ABSTRACT. In view of a resurgence of concern about the measurement problem, it is pointed out that the Relativistic Transactional Interpretation (RTI) remedies issues previously considered as drawbacks or refutations of the original TI. Specifically, once one takes into account relativistic processes that are not representable at the nonrelativistic level (such as particle creation and annihilation, and virtual propagation), absorption is quantitatively defined in unambiguous physical terms. RTI therefore provides a welldefined terminus to what appears to be a necessary infinite regress concerning ‘absorption’ when only the nonrelativistic level is considered. In addition, specifics of the relativistic transactional model demonstrate that the Maudlin ‘contingent absorber’ challenge to the original TI cannot even be mounted: basic features of established relativistic field theories (in particular, the asymmetry between field sources and the bosonic fields, and the fact that slowmoving bound states, such as atoms, are not offer waves) dictate that the ‘slowmoving offer wave’ required for the challenge scenario cannot exist. It is concluded that issues previously considered obstacles for TI are no longer legitimately viewed as such, and that reconsideration of the transactional picture is warranted in connection with solving the measurement problem. PDF here: On the Status of the Measurement Problem Arxiv7

Ruth Kastner posted an update in the group 2017 International Workshop: Collapse of the Wave Function 4 years, 12 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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