Reply To: Quantum causal models, faithfulness and retrocausality (onl. 7/16 @ 11pm UTC+10)

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AvatarMark Stuckey

Hi Pete,

I agree completely with your premise that “since it is also the case that we occupy this reality and we have been able to provide rather successful causal and dynamical models representing the phenomena around us, then there must be some sort of story explaining how we can do this given that reality is actually a 4D block obeying said constraints.” This is essentially (and formally) the claim that correspondence with successful existing theories is required of all new theories. However, this is a bit tricky for a new theory (like RBW) that underwrites quantum physics (successful existing theory) because it’s precisely quantum physics that we want to interpret. So, if Bob is looking for a dynamical interpretation of quantum physics and is given an adynamical theory underwriting quantum physics, then Bob is not going to be satisfied.

I also agree completely that “we don’t do this by giving some competing dynamical story in terms of time evolving laws. What we’re after is a dynamical story that arises as a result of a combination of the global constraints and our spatiotemporally embedded perspective,” unless of course you’re using the formalism of that competing dynamical story to make formal correspondence with existing theories. In that case, you might then also satisfy Bob.

Finally, I agree completely with you about the epistemic (rather than ontic) view of retrocausality in a BW with a global constraint: “That this story is dynamical is a feature of how we tell it, not as a result of some objective ‘dynamicism’ in reality. And I think this is the most fruitful way to understand retrocausality.” But, I suspect Bob would disagree, as he seems to desire an ontic basis for retrocausality.

Thus, there doesn’t seem to be any disagreement between us, but does Bob have to abandon his desideratum? I don’t think so. I think it may be possible to construct a corresponding (ontic) dynamical model that isn’t superfluous relative to the 4D adynamical global constraint model, e.g., PTI and RBW. These two models aren’t ontologically equivalent, but they are complementary. It just comes down to how you view consciousness and experience.

For example, if you adopt an “Eastern” worldview a la Nisargadatta Maharaj (author of “I Am That”), the dynamical, time-evolved experience is not fundamental, as seen in this quote (442, 1973):

‘Who am I’. The identity is the witness of the person and sadhana consists in shifting the emphasis from the superficial and changeful person to the immutable and ever-present witness.

In that view, accounts in 4D with adynamical global constraints are (probably) fundamental to 3D time-evolved accounts with dynamical laws. However, in the “Western” worldview, physics is done by 3D time-evolved beings who can imagine a 4D perspective (and alter their perceptions through meditation, for example). But, just because we can imagine it doesn’t make it ontic. Thus, in the “Western” worldview, the 3D time-evolved accounts with dynamical laws are fundamental to accounts in 4D with adynamical global constraints. Note: A mere dynamical dressing for a 4D account a la “pseudo-time” processes, doesn’t constitute a fundamental dynamical account. I’m thinking, again, of something like the relationship between PTI and RBW where the formal mechanisms of PTI aren’t superfluous relative to those of RBW. That’s the sense in which I mean they’re complementary and not equivalent.

Hopefully, I haven’t strayed too far from rigorous discourse 🙂

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