A recent ontological variant of Cramer’s Transactional Interpretation, called “Possibilist Transactional Interpretation” or PTI, is extended to the relativistic domain. The present interpretation clarifies the concept of ‘absorption,’ which plays a crucial role in TI (and in PTI). In particular, in the relativistic domain, coupling amplitudes between fields are interpreted as amplitudes for the generation of confirmation waves (CW) by a potential absorber in response to offer waves (OW), whereas in the nonrelativistic context CW are taken as generated with certainty. (...) It is pointed out that solving the measurement problem requires venturing into the relativistic domain in which emissions and absorptions take place; nonrelativistic quantum mechanics only applies to quanta considered as ‘already in existence’ (i.e., ‘free quanta’), and therefore cannot fully account for the phenomenon of measurement, in which quanta are tied to sources and sinks. (shrink)

Lewis has recently argued that Maudlin׳s contingent absorber experiment remains a significant problem for the Transactional Interpretation. He argues that the only straightforward way to resolve the challenge is by describing the absorbers as offer waves, and asserts that this is a previously unnoticed aspect of the challenge for TI. This argument is refuted in two basic ways: it is noted that the Maudlin experiment cannot be meaningfully recast with absorbers described by quantum states; instead the author replaces it with (...) an ordinary which-way experiment; and the extant rebuttals to the Maudlin challenge in its original form are not in fact subject to the alleged flaws that Lewis ascribes to them. This paper further seeks to clarify the issues raised in Lewis’ presentation concerning the distinction between quantum systems and macroscopic objects in TI. It is noted that the latest, possibilist version of TI has no ambiguity concerning macroscopic absorbers. In particular, macroscopic objects are not subject to indeterminate trajectories, since they are continually undergoing collapse. It is concluded that the Maudlin challenge poses no significant problem for the transactional interpretation. (shrink)

This paper explores the possibility of an event interpretation of quantum field theory.

The paper considers the absorber theory of radiation by (Wheeler and Feynman 1945) and (Wheeler and Feynman 1949) and advances the idea that the theory is grounded on the philosophical intuition of overall processes. Such intuition consists of having to consider advanced and retarded radiation as well as the interaction between absorbers and emitter. I discuss the discrepancy between microdynamic time-symmetry and the asymmetry of the experimental evidences. In doing so, I consider (Price, 1991)'s reformulation of the theory and argue (...) that it overlooks the philosophical intuition. I then compare the overall process idea with some accounts of holism and ultimately suggest that it also played an important role in Feynman's later works. (shrink)

This paper explains the delayed choice quantum eraser of Kim et al. in terms of the transactional interpretation of quantum mechanics by Cramer. It is kept deliberately mathematically simple to help explain the transactional technique. The emphasis is on a clear understanding of how the instantaneous “collapse” of the wave function due to a measurement at a specific time and place may be reinterpreted as a relativistically well-defined collapse over the entire path of the photon and over the entire transit (...) time from slit to detector. This is made possible by the use of a retarded offer wave, which is thought to travel from the slits to the detector and an advanced counter wave traveling backward in time from the detector to the slits. The point here is to make clear how simple the transactional picture is and how much more intuitive the collapse of the wave function becomes if viewed in this way. Also, any confusion about possible retro-causal signaling is put to rest. A delayed choice quantum eraser does not require any sort of backward in time communication. This paper makes the point that it is preferable to use the TI over the usual Copenhagen interpretation for a more intuitive understanding of the quantum eraser delayed choice experiment. Both methods give exactly the same end results and can be used interchangeably. (shrink)

The Frauchiger–Renner Paradox is an extension of paradoxes based on the “Problem of Measurement,” such as Schrödinger’s Cat and Wigner’s Friend. All these paradoxes stem from assuming that quantum theory has only unitary physical dynamics, and the attendant ambiguity about what counts as a ‘measurement’—i.e., the inability to account for the observation of determinate measurement outcomes from within the theory itself. This paper discusses a basic inconsistency arising in the FR scenario at a much earlier point than the derived contradiction: (...) namely, the inconsistency inherent in treating an improper mixture as a proper, epistemic mixture. This is an illegitimate procedure that is nevertheless endemic if quantum theory is assumed to be always unitary. In contrast, under a non-unitary account of quantum state reduction yielding determinate outcomes, the use of a proper mixture for measurement results becomes legitimate, and this entire class of paradoxes cannot be mounted. The conclusion is that the real lesson of the FR paradox is that it is the unitary-only assumption that needs to be critically reassessed. (shrink)

It is argued that if the non-unitary measurement transition, as codified by Von Neumann, is a real physical process, then the ‘probability assumption’ needed to derive the Second Law of Thermodynamics naturally enters at that point. The existence of a real, indeterministic physical process underlying the measurement transition would therefore provide an ontological basis for Boltzmann’s Stosszahlansatz and thereby explain the unidirectional increase of entropy against a backdrop of otherwise time-reversible laws. It is noted that the Transactional Interpretation of quantum (...) mechanics provides such a physical account of the non-unitary measurement transition, and TI is brought to bear in finding a physically complete, non-ad hoc grounding for the Second Law. (shrink)

It was first suggested by Albert that the existence of real, physical non-unitarity at the quantum level would yield a complete explanation for the increase of entropy over time in macroscopic systems. An alternative understanding of the source of non-unitarity is presented herein, in terms of the Transactional Interpretation. The present model provides a specific physical justification for Boltzmann’s Stosszahlansatz, thereby changing its status from an ad hoc postulate to a theoretically grounded result, without requiring any change to the basic (...) quantum theory. In addition, it is argued that TI provides an elegant way of reconciling, via collapse, the time-reversible Liouville evolution with the time-irreversible evolution inherent in master equations. The present model is contrasted with the GRW ‘spontaneous collapse’ theory previously suggested for this purpose by Albert. (shrink)

The Transactional Interpretation has been subject at various times to a challenge based on a type of thought experiment first proposed by Maudlin. It has been argued by several authors that such experiments do not in fact constitute a significant problem for the transactional picture. The purpose of this work is to point out that, when the relativistic level of the interpretation is considered, Maudlin-type challenges cannot even be mounted, since the putative 'slow-moving offer wave,' taken as subject to contingent (...) confirmation, does not exist. This is a consequence of the Davies relativistic quantum-mechanical version of the direct-action theory together with the asymmetry between fermionic field sources and bosonic fields. The Maudlin challenge therefore evaporates completely when the relativistic level of the theory is taken into account. (shrink)