Understanding Quantum Entanglement and Retrocausality

If you want to understand Quantum Entanglement you need to tangle/wrestle with the Bell Inequalities argument.

See… https://arxiv.org/pdf/quant-ph/0208161.pdf

For this you need to:

A/ Have an understanding of the assumptions in the Bell Inequality argument

B/ An acceptance that some (at least 1) of assumptions in It have to be violated to support experimental evidence.

The core assumptions that seem to be open to question;

• 1 no Retrocausality (Referred to in the paper as “Backward causation”
• 2 no Non-Local Action at a distance
• 3 Physical Realism
• 4 no Conspiracy (such as Super Determinism)
• 5 Experimenters have choice (Free Will)

The author argues we need to keep 3, 4 and 5 to have a physically meaningful world where scientific evidence is illuminating and experimenters have choice.

Thus given experimental results we ditch 2.

But if Spacetime is not “local” in the general sense, shouldn’t that mean 1 should not be implicitly dropped?

The argument the author provides is because it leads to paradoxes, but this isn’t necessarily so. At a retrocausal event, there is the possibility of “world branching” in the MWI of QM. So no “grandfather paradox” arises. The Many Minds Interpretation is viable if the observer is the cause of collapse/decoherence in this Everett model of the UWF.

Furthermore. As for objections to assumption 5, 1 being false enables 5 to be true. That’s good as it preserves the viability of experimental physicists being able to CHOOSE how they interact with a real-world! If 1 is true (no Retrocausality) determinism arguments may defeat 5. The consequence is then that determinism becomes superdeterminism, a physical conspiracy notion that not only do prior events ONLY cause future ones but experimental tests are predetermined to give consistent results, this being done from the earliest initial conditions, ie., the Big Bang. We don’t have free will or the ability to test the conjecture!

That “conspiracy” renders physics (all scientific endeavours) a futile exercise. Given that conspiracy is not a scientific hypothesis, it’s an ideology. Ideologies can be challenged if alternative fitting ideology can be selected by inference to the best explanation. What is “best” is a value judgement. I choose freedom.

As Anton Zeilinger said on this…

“[W]e always implicitly assume the freedom of the experimentalist... This fundamental assumption is essential to doing science. If this were not true, then, I suggest, it would make no sense at all to ask nature questions in an experiment since then nature could determine what our questions are, and that could guide our questions such that we arrive at a false picture of nature”

Having said the above if we accept Retrocausality exists (and there is good evidence it does) then we can defeat the pernicious conspiracy notion of superdeterminism (because Retrocausality enables agent causation that enables Free Will I contest, eg., a future self can interact with present self to "nudge" otherwise event causation only decisions).

Evidence/Support for Retrocausality in Physics can be found in Two-State Vector Formalism arguments by Aharonov et al, Transaction Interpretation of QM by Cramer et al, ER=EPR conjecture by Susskind and Maldecena, and various Delayed Choice Quantum Erasure experiments are claimed to be supportive (though not without contest).

See... https://plato.stanford.edu/entries/qm-retrocausality/

Furthermore, in General Relativity (GR) the possibility of Closed Timelike Curves is a theoretical viable solution. In a future integration of QM and GR to a Quantum Gravity solution, it may be expected that Quantum Entanglement in spatial dimensions should extend to spacetime timeline dimensions.

Image source: https://www.quantamagazine.org/how-bells-theorem-proved-spooky-action-at-a-distance-is-real-20210720