Reply To: Quantum Oblivion and Hesitation

AvatarEliahu Cohen

Dear Ken and Mark,

Many thanks for the constructive remarks and for highlighting these two key issues within the TSVF and probably within any other time-symmetric formulation of QM. I know your questions are strictly related to your contributions in this workshop, so I’ll try to study them. In the meanwhile, rather than decisive answers, I’d like to share with you a few reflections:

With regards to Ken’s question:
Relying primarily on (a variant of an EPRB experiment is analyzed where a set of weak measurements is performed before the preparation and final projective measurements) our claim here was that the entangled particles were in fact “aware” of their actual future (separately, in spacetime, rather than configuration space) which determined their weak values in the past. At this point, Aharonov and Elitzur differ. The first believes that this provides a full local description of experiments performed at intermediate times (please see “Measurements on EPR States” in, while the latter thinks that the transactional zigzag is essential, i.e., that the future of the first particle comes back to the joint past through which it affects the future of the second particle (locally all the way).
Other way to tackle this difficulty with the configuration space, could be analyzing this problem in a time-symmetric Heisenbreg representation where each particle has a set of time-dependent deterministic operators, but then the notion kinematic nonlocality is just altered to dynamic nonlocality.
Which of the three accounts do you prefer?
By the way, this problem was recently discussed in:

With regards to Mark’s question:
At first I admit that block universe and the TSVF seem to walk hand in hand. However, my colleagues and I try to avoid the block universe approach (I guess for psychological rather than physical reasons), i.e. there are definite pre- and post-selected states to the universe, but also some freedom in the present resulting from quantum uncertainty. In the Oblivion and Hesitation papers, we endorsed indeed the meta-time approach which seems to resonates better with the idea of self-cancelling set of events. We can’t really imagine this happening in an atemporal universe, while using meta-time this hesitant behavior becomes more intuitive.
However, we did not provide a mechanism for a meta-time. One of the reasons for that is the same divergence again:
Avshalom holds for many years now the “becoming approach”:, on which I believe he would elaborate in reply to your questions about the “Too Late Experiment”.
I (on the other hand?) tend to accept Yakir’s approach in – all instants are linked via a long chain of pre- and post-selections where the post-selection of the N instant is maximally correlated to the N+1 instant’s pre-selection.
I believe that in both accounts the arrow of time originates from the direction in which correlations are created, but the true “emergence” is related to this elusive meta-time which we still do not fully understand. What do you think?

Sorry for the lengthy replies and thanks again,

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