John Cramer’s transactional interpretation of quantum mechanics (TIQM) is billed as resolving the fuzzy agnosticism of the Copenhagen interpretation while avoiding the alleged ontological excesses of the Many Worlds Interpretation. Yet it has a low profile.
Is this because no-one care anymore about ontology in physics, or is there something about TIQM which undermines belief in it?
Nobody has explained to me how Shor's quantum factorization algorithm works under the transactional interpretation, and I expect this is because the transactional interpretation cannot actually explain this algorithm. If it can't, then chances are the transactional interpretation doesn't actually work. (I have looked at some of the papers that purport to explain the transactional interpretation, and have found them exceedingly vague about the details of this interpretation, but assuming this interpretation is actually valid, maybe somebody else with more determination could figure these details out.)
It's a combination of all these things and more. Most importantly, the TIQM interpretation is nonsense and all the positive words you hear about it are just unjustifiable hype promoted purely by John Cramer himself.
Ontology - or "realism", as it is technically called in quantum mechanics - has been falsified in physics in the mid 1920s and it can never be "unfalsified" again. It's established that objects don't possess well-defined properties before they're measured. This insight continues to be hard to swallow for many people - however it doesn't mean that there is anything questionable about it.
The TIQM merges all the usual misconceptions about the "real wave function" with some very special inconsistencies such as retrocausality - the influence of the future on the past - that is obtained by a bizarre interpretation of the Feynman-Wheeler theory, a theory that turned out to be incorrect by itself (although it helped to stimulate Feynman and others to find the right rules of quantum field theory). Concerning the Feynman-Wheeler theory, its historical role, and some of its problems, see
Wheeler-Feynman theory, QED without fields, vacuum polarization
I have come across a very simple question or critique of the Transactional Interpretation in an article "Nine formulations of Quantum Mechanics". The multiple authors of this 2002 AMJ paper are QM physics teachers.
They ask how "two particle" transactional handshakes work: are there "two handshakes across spacetime" or "one handshake across Configuration Space"? Without an answer to this question they are unable to "report on how the TI differentiates between bosons and fermions".
I have a new approach to TI which is discussed in my forthcoming book for CUP. It will be available in fall 2012. I don't think the basic transactional picture has any problem accounting for quantum phenomena including multiparticle states, but the ontology of my version is different from Cramer's. I will look into Shor's algorithm, but I don't see why this would constitute a challenge for TI because TI has no problem with quantum computation that I know of. Any quantum system can be modeled in the transactional picture. The only situations regarded as challenges are contingent absorber experiments such as Maudlins; this issue is addressed and resolved in the book and a preview is here: http://philsci-archive.pitt.edu/8963/
Some recent papers on TI are on my website: rekastner.wordpress.com; some of this material is in the book.
Thanks for your interest.
I suspect a problem people have with TIQM is that Wheeler-Feynman absorber is woven into this. The advanced potentials and the rest are a bit much for many to swallow.
I think TI is the best interpretation in quantum mechanics. TI is also one step better to the Wheeler Feynman absorption theory. Wheeler Feynman's absorber theory is a spherical theory. That is to say, both retarded waves and advanced waves are spherical waves.
However, both the retarded wave and the advanced wave in TI are plane waves. In Cramer's TI, the source emits a retarded wave in one direction and an advanced wave in the opposite direction.
I am not studying quantum theory. I am studying electromagnetic field theory, studying antennas and electromagnetic waves. In 2017, I further proposed the mutual energy flow theorem based on my own mutual energy theorem proposed in 1987. This mutual energy theorem is in the frequency domain, and if converted to the time domain, it is the time-domain reciprocity theorem proposed by Welch in 1960. I found that the shape of mutual energy flow is pointed at both ends and large in the middle, which can explain both waves and particles simultaneously. That is to say, mutual energy flow can solve the problem of wave particle duality.
I found that this mutual energy flow is very close to the TI of quantum mechanics. In TI, there is a handshake between retarded waves and advanced waves. In my theory of mutual energy flow, retarded waves and advanced waves synchronize and together form the mutual energy flow. The difficulty with TI is that the hysteresis wave emitted by the sink is just 180 degrees out of phase with the hysteresis wave emitted by the source, so it just cancels out. The leading wave emitted by the source and the leading wave emitted by the sink well maintain a phase difference of just 190 degrees, so it just cancels out. Why is it exactly 180 degrees. TI did not provide an answer. In my proposed theory of mutual energy flow, this 180 degree is due to the reversal of the magnetic field on both sides of the plane current.
There is also a certain difference between my mutual energy flow theory and Maxwell's electromagnetic theory. The electromagnetic waves generated by the source and sink here are both reactive power waves. When reactive power waves propagate in space, they transfer energy to space while returning it to its source. In Maxwell's electromagnetic theory, electromagnetic waves are of active power.
My theory of mutual energy flow is a good implementation for TI. Recently, I have published over 10 papers on mutual energy flow, which support TI. These papers can be found by searching for the "Mutual Energy Flow Theorem".
Ron Maiman is mistaken concerning TI and many particles. In fact TI applies perfectly well to many-particle systems; there is no restriction on the number or particles nor is entanglement excluded in any way. I don't know how he got this wrong impression. Cramer himself discusses a TI analysis of the EPR experiment here: https://arxiv.org/pdf/1503.0039 (Cramer and I don't happen to agree on all philosophical aspects of offer and confirmation waves, but it's clear that entanglement is no problem for TI.) Also concerning Roy Simpson's concern: the relativistic form of TI, RTI, clearly distinguishes between bosons and fermions (see, e.g., my publication arXiv:1610.04609) and provides quantitative specifics concerning the physics of the OW/CW interation. This material is in my CUP 2nd edition and the relevant excerpt from Chapter 5 is available here: https://arxiv.org/pdf/2101.00712
