Possibilist Transactional Interpretation

[Ruth Kastner]

Thanks to Ken Wharton for running this workshop.
As many of you know, I’ve been working on an extension of Cramer’s Transactional Interpretation with a possibilist ontology. I’ve argued that this solves the measurement problem and provides a unified account of nonrelativistic and relativistic quantum theory. It also offers promise for a theory of quantum gravity, through its account of spacetime emergence. I welcome questions/comments/suggestions for further development of the model.

Here are key references:

Kastner, R. E. (2012) The Transactional Interpretation of Quantum Mechanics: The Reality of Possibility. Cambridge University Press.

Kastner, R. E. (2014) “On Real and Virtual Photons in the Davies Theory of Time-Symmetric Quantum Electrodynamics,” Electronic Journal of Theoretical Physics 11, 75–86. Preprint version: http://arxiv.org/abs/1312.4007

A Unified Account of Relativistic and Non-Relativistic Quantum Theory

‘The Emergence of Spacetime: Transactions and Causal Sets,” http://arxiv.org/abs/1411.2072

[Michael B. Heaney]

Hi Ruth,

Thanks for your post. I’m now reading your interesting book “Understanding our Unseen Reality: Solving Quantum Riddles.” Near the end of Chapter 2, you make the point that “quantum objects are wave-like entities that need to be described by complex numbers…Anything observable in the world of appearance must be described by real numbers…” and therefore quantum objects exist outside of spacetime. Is this an accurate reading? If so, it seems to rule out any realist interpretation of quantum mechanics. Is this your viewpoint? Ken, what are your thoughts about this?

Regards,

Michael

[Miroljub Dugic]

Hi Michael,

could you please elaborate a bit more on, as you say, “[quantum objects exist outside of spacetime. Is this an accurate reading? If so, it seems] to rule out any realist interpretation of quantum mechanics”? May it be the case that spacetime is emergent for the quantum realm that still allows for a realist interpretation?

Best regards,

Miroljub

[Michael B. Heaney]

Hi Miroljub,

Thanks for your question. Since Ruth wrote this, I will defer to her for an elaboration.

Best regards,

Michael

[Ruth Kastner]

Hi and sorry for the late reply.
The answer is that ‘real’ is not equivalent to ‘existing in spacetime’.
I take quantum states as referring to real objects that exist as a quantum substratum, outside spacetime, and that spacetime events are emergent from that real substratum–as Miroljub notes.
So the idea is that we need to expand our notion of what it means to be ‘real’.

[Alan Harrison]

Hello Ruth et al.,

Another way to answer Michael’s question, which I believe is equivalent to Ruth’s answer, is that not everything that is real is observable. The obvious example (from a realist perspective) is the wavefunction itself.

[Ruth Kastner]

Thanks Alan, this raises the issue of interpretation of the wf. It’s a vexed issue because most people presuppose that ‘real’ = ‘spacetime object’ but in general the wf is not compatible with spacetime existence. For those who accept that definition of real (whether tacitly or explicitly), this leads to antirealism about the wf on the one hand, or pseudo-classical approaches (hidden variables) on the other. If we let go of that presumption, we have more interpretive options.

[Michael B. Heaney]

Thanks, that clarifies it!

[Miroljub Dugic]

Hi Ruth,

may I say: (i) space and/or time are not physically fundamental, and (ii) there are no ‘particles’ on the fundamental physical level either?

Best regards,

Miroljub

[Ruth Kastner]

I would agree with that. In PTI what we call ‘particles’ are just actualized transactions bringing about the observed spacetime events.

[Mark Stuckey]

Hi Ruth,

I’ve seen Cramer’s “pseudo-time” process of TI mentioned in several topics of this forum being proposed as a way of introducing change and Becoming to the BW (blockworld). I have no idea what meta-time change means empirically and neither it seems do they. In my opinion, if you want an empirically/experientially meaningful notion of change and Becoming in a retrocausal account, you want PTI. I’ve said as much several times in other topics without once having it acknowledged. I can only assume there is something they dislike about PTI, but they’re being too polite to tell me. Do you know what that is?

Sorry, I’m a bit autistic so I need people to be direct.

Mark

[Ruth Kastner]

Thanks Mark,

I don’t know either. Hey out there, please tell us what you don’t like about PTI.
But please let your critique be based on an open-minded reading of the published literature, unlike some critiques out there 🙂

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