
Ken Wharton joined the group Workshop on Wigner’s Friend 2018 5 months, 1 week ago

Ken Wharton replied to the topic Does the psiepistemic view really solve the measurement problem? in the forum 2016 International Workshop on Quantum Observers 3 years, 2 months ago
Hi Shan,
Turning back to your question in #3303, concerning randomness:
A central point of the paper I posted in this forum is that all of the probabilities in retrocausal quantum models can be classical/conventional in the sense that they all result from a lack of knowledge. But there are two different parts of this. First is the knowledge…[Read more]

Ken Wharton replied to the topic Does the psiepistemic view really solve the measurement problem? in the forum 2016 International Workshop on Quantum Observers 3 years, 2 months ago
Mark: concerning “realist psiepistemic view”. There’s no problem with the basic idea, so long as “realist” clearly modifies “view”. But a different parsing might make it seem that “realist” modifies “psi”, which would imply exactly the opposite of psiepistemic (psiontic). That’s all I was getting at… 🙂

Ken Wharton replied to the topic Does the psiepistemic view really solve the measurement problem? in the forum 2016 International Workshop on Quantum Observers 3 years, 2 months ago
Shan: I’m not sure what you mean by “essential randomness”, or whether that would be ‘good’ or ‘bad’. But you are correct to imply that if there is some ‘special observable’ A in the real system that is perfectly correlated with the measurement B that we utilize on that system, then this correlation needs to be explained causally.
One option is…[Read more]

Ken Wharton replied to the topic Does the psiepistemic view really solve the measurement problem? in the forum 2016 International Workshop on Quantum Observers 3 years, 2 months ago
Thanks for this, Shan.
I’m worried you’re setting up a bit of a straw man version of psiepistemic models (you call it the “realist psiepistemic” view, an interesting choice of words). I’d be surprised if there were many (or any!) quantum foundations people who take such a view.
Specifically, you are ascribing the following logic to anyone…[Read more]

Ken Wharton started the topic Measurements as External Constraints in the forum 2016 International Workshop on Quantum Observers 3 years, 2 months ago
When two systems are in spatial contact, it’s natural for the bigger system to constrain the smaller system, not viceversa. For instance, consider classical statistical mechanics. When one system has an overwhelming number of possible internal states, it will act like a thermal reservoir for smaller systems in contact with it, constraining the…[Read more]


Ken Wharton replied to the topic Are retrocausal accounts of nonlocality conspiratorial? A toy model. in the forum Timesymmetric theories 3 years, 8 months ago
Hi Travis,
Wow! It’s very nice to hear we’re in agreement about both the framing of the problem and what the solution must look like. Apart from a single word, I’m also in agreement with:
“…it [had] better turn out that the boundary conditions on S’ *imply*, via the application of the basic dynamical postulates of the theory, the same sort…[Read more]

Ken Wharton replied to the topic Are retrocausal accounts of nonlocality conspiratorial? A toy model. in the forum Timesymmetric theories 3 years, 8 months ago
Hi Travis,
There are many aspects of the measurement problem, but I think the one that is hardest for retrocausal theories is that there should be no difference between an *interaction* and a *measurement*, since one can’t define a hard distinction between the two. Standard QM of course has this problem. It incorporates mere interactions into…[Read more]

Ken Wharton replied to the topic General "Block Universe" Discussion in the forum Timesymmetric theories 3 years, 8 months ago
Ian; the multiverse isn’t a BW, which points to hidden variables. But one doesn’t need the sort of HV’s that bother you: all you need is that the *future* is a hidden variable, hidden from our knowledge, and you can have a BW theory that is fundmanentally stochastic. Surely you don’t have a problem with treating future events (events that lie…[Read more]

Ken Wharton replied to the topic Are retrocausal accounts of entanglement unnaturally finetuned? in the forum Timesymmetric theories 3 years, 8 months ago
Hi Dustin; Thanks for the kind words!
As for giving the WoodSpekkens argument too much credit… If there was an existing retrocausal model they were attacking, that gave the right probabilities already, I’d certainly agree with you. But they’re framing it as an argument against trying to develop such a model in the first place. And since…[Read more]

Ken Wharton replied to the topic Retrocausation vs Retrodiction in the forum Timesymmetric theories 3 years, 8 months ago
> I cannot make any sense of your reference to “which aspect of Bell’s theorem doesn’t go through” somehow associated with “statistical independence of the allowed histories”. Would you care to clarify?
I have a detailed but very simple toyIsing model showing how statistical independence can fail at the level of allowed histories in [Read more]

Ken Wharton replied to the topic Are there any pressing problems? in the forum Panel Discussion 3 years, 8 months ago
As I see it, the biggest pressing problem is how to make sense of QM and GR in the same consistent framework. (I’m not sure if this counts as a “practical purpose” in most people’s accounts, but it does in mine.) Certainly, many people don’t think we need to wait for an ability to collect empirical evidence in situations where both QM and GR are…[Read more]

Ken Wharton replied to the topic General "Block Universe" Discussion in the forum Timesymmetric theories 3 years, 8 months ago
Ian: if you are just referring to the “Block” itself, see my #2711 above.
If you’re talking about classical randomness, or stochastic theories, another way to think about it is this: Most people’s trouble with the Block Universe has to do with the *future*. Very few people have trouble imagining a Blockyear1999. (Do you?) So any randomness…[Read more]

Ken Wharton replied to the topic Retrocausation vs Retrodiction in the forum Timesymmetric theories 3 years, 8 months ago
Thanks, Bob – I have a pretty clear idea of where our paths diverge now.
Still, I happen to think that far more clarity is gained than lost when thinking about the CH framework choice as a hidden variable. (It’s certainly “hidden” at first, right?) Specifically, when thinking this way, it becomes far clearer which aspect of Bell’s theorem d…[Read more]

Ken Wharton replied to the topic General "Block Universe" Discussion in the forum Timesymmetric theories 3 years, 8 months ago
Hi Ian! Yes, I’m looking forward to talking about this in person…
I wouldn’t say that the Block Universe is particularly motivated by retrocausality — it’s best motivated by general relativity! (So yes, it does imply some ontological status of spacetime, modulo diffeomorphisms, etc.)
And curiously, many people interested in retrocausality…[Read more]

Ken Wharton replied to the topic Experimental tests of the Special State theory in the forum Timesymmetric theories 3 years, 8 months ago
Hi Larry,
Thanks for posting this; I don’t think your ideas are getting their deserved attention from the wider quantum foundations community, and as you know am trying to inform people about them in my own work.
In my piece here in this forum, I talk about your oneparticle model and conclude that it is effectively retrocausal. (The future…[Read more]

Ken Wharton replied to the topic Are retrocausal accounts of nonlocality conspiratorial? A toy model. in the forum Timesymmetric theories 3 years, 8 months ago
Hi Travis and Dustin,
Thanks for the interesting discussion! I thought I’m chime in with a few points of my own…
Travis, on your point #2, you never mentioned another aspect of locality (really, a prerequisite!): restricting models to those that have exclusively spacetimelocal beables. To me, *that’s* the important thing that…[Read more]

Ken Wharton replied to the topic Causality and quantum mechanics (Online 7/15 @ 10 p.m. to Midnight UTC7) in the forum Timesymmetric theories 3 years, 8 months ago
All good questions about the cause/correlation issues… Do you have a classical example in mind as an answer to your last question?
Still, you can’t carefully address these questions without comparing your definition of causation to some *other* definition of causation. Even if you don’t want to bring in other causation accounts, where your…[Read more]

Ken Wharton replied to the topic Are retrocausal accounts of entanglement unnaturally finetuned? in the forum Timesymmetric theories 3 years, 8 months ago
Hi Nathan,
I think you’re almost exactly right about what should be considered a “good” variable, but I’ll throw one suggested change at you: Instead of taking the log of the number of possible ontic *states*, what about the log of the number of possible ontic *histories*? This associates “entropy” with regions of spacetime rather than…[Read more]
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