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 long-sought 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 direct-action theory that is off-putting? Is it because both Wheeler and Feynman abandoned their theory (though Wheeler was later advocating it again in 2003)? Comments welcome.

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 non-unitary […]

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 ill-founded.

Paper link here: Reply to LM IJQF4

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 non-relativistic level (such as particle creation and annihilation, and virtual propagation), absorption is quantitatively defined in unambiguous physical terms. RTI therefore provides a well-defined terminus to what appears to be a necessary infinite regress concerning ‘absorption’ when only the non-relativistic 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 slow-moving bound states, such as atoms, are not offer waves) dictate that the ‘slow-moving 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