In 1994, Maudlin proposed an objection to retrocausal approaches to quantum mechanics in general, and to the transactional interpretation in particular, involving an absorber that changes location depending on the trajectory of the particle. Maudlin considered this objection fatal. However, the TI did not die; rather, a number of responses were developed, some attempting to accommodate Maudlin's example within the existing TI, and others modifying the TI. I argue that none of these responses is fully adequate. The reason, I submit, (...) is that there are two aspects to Maudlin's objection; the more readily soluble aspect has received all the attention, but the more problematic aspect has gone unnoticed. I consider the prospects for developing a successful retrocausal quantum theory in light of this second aspect of the objection. (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 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)

Although many find it hard to believe that every physical thing—no matter how simple or small—involves some form of consciousness, panpsychists offer the reassurance that their claims are perfectly compatible with everything physics has to say about the physical world. This is because although physics has a lot to say about causal and structural properties it has nothing to say about the intrinsic natures of physical things, and if physics is silent in this regard it is perfectly possible that everything (...) physical has an experiential intrinsic nature. Following in Thomas Nagel’s footsteps, panpsychists have also argued that by revealing that everything is composed of the same fundamental ingredients, physics provides grounds for holding that if any physical things (e.g. our neural processes) have an experiential intrinsic nature then all must. My main contention in this paper is that the relationship between physics and panpsychism is considerably more complex than panpsychists have tended to assume. Nagel’s reasoning may be sound in the context of simplistic atomic theories which posit just one kind of fundamental particle. However, it begins to look distinctly dubious in the context of the diverse range of primitive entities that are to be found in the Standard Model of particle physics. Galen Strawson has suggested that mass-energy interconvertibility should be regarded as evidence that everything physical has the same intrinsic nature. I suggest Strawson’s claim relies on a dubious construal of the nature of energy. Special relativity is another of the cornerstones of contemporary physics, and it too makes life difficult for panpsychists, a fact which emerges when we consider what it would like to be a ray of light. However in this case I suggest that there is an interesting—if radical—move open to the panpsychist: they can simply deny that light exists. To conclude I briefly consider whether what QCD has revealed about the nature of mass poses a problem for panpsychism. (shrink)

The transactional interpretation of quantum mechanics, following the time-symmetric formulation of electrodynamics, uses retarded and advanced solutions of the Schrödinger equation and its complex conjugate to understand quantum phenomena by means of transactions. A transaction occurs between an emitter and a specific absorber when the emitter has received advanced waves from all possible absorbers. Advanced causation always raises the specter of paradoxes, and it must be addressed carefully. In particular, different devices involving contingent absorbers or various types of interaction-free measurements (...) have been proposed as threatening the original version of the transactional interpretation. These proposals will be analyzed by examining in each case the configuration of absorbers and, in the special case of the so-called quantum liar experiment, by carefully following the development of retarded and advanced waves through the Mach-Zehnder interferometer. We will show that there is no need to resort to the hierarchy of transactions that some have proposed, and will argue that the transactional interpretation is consistent with the block-universe picture of time. (shrink)

Regular physics is unsatisfactory in that it fails to take into consideration phenomena relating to mind and meaning, whereas on the other side of the cultural divide such constructs have been studied in detail. This paper discusses a possible synthesis of the two perspectives. Crucial is the way systems realising mental function can develop step by step on the basis of the scaffolding mechanisms of Hoffmeyer, in a way that can be clarified by consideration of the phenomenon of language. Taking (...) into account such constructs, aspects of which are apparent even with simple systems such as acoustically excited water (as with cymatics), potentially opens up a window into a world of mentality excluded from conventional physics as a result of the primary focus of the latter on the matter-like aspect of reality. (shrink)

It is suggested that the apparently disparate cosmological phenomena attributed to so-called ‘dark matter’ and ‘dark energy’ arise from the same fundamental physical process: the emergence, from the quantum level, of spacetime itself. This creation of spacetime results in metric expansion around mass points in addition to the usual curvature due to stress-energy sources of the gravitational field. A recent modification of Einstein’s theory of general relativity by Chadwick, Hodgkinson, and McDonald incorporating spacetime expansion around mass points, which accounts well (...) for the observed galactic rotation curves, is adduced in support of the proposal. Recent observational evidence corroborates a prediction of the model that the apparent amount of ‘dark matter’ increases with the age of the universe. In addition, the proposal leads to the same result for the small but nonvanishing cosmological constant, related to ‘dark energy,’ as that of the causet model of Sorkin et al. (shrink)

It is argued that Niels Bohr ultimately arrived at positivistic and antirealist-flavored statements because of weaknesses in his initial objective of accounting for measurement in physical terms. Bohr’s investigative approach faced a dilemma, the choices being conceptual inconsistency or taking the classical realm as primitive. In either case, Bohr’s ‘Complementarity’ does not adequately explain or account for the emergence of a macroscopic, classical domain from a microscopic domain described by quantum mechanics. A diagnosis of the basic problem is offered, and (...) an alternative way forward is indicated. (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)