Dear Jean,

Your paper is very well written, and a pleasure to read. I thank you.

However, I think your arguments are more than a decade out of date. I analyzed the nonlocality issue of EPRB correlations in Chs. 23 and 24 of my book CONSISTENT QUANTUM THEORY (http://quantum.phys.cmu.edu/CQT), where I considered EPRB correlations, and…[Read more]

Hi Chris, Yes, I agree, we’re not making any progress, and it seems a good time to wrap this up and agree to continue over beers someday. I feel I should wrap up some loose ends, but this will be my last post so you can take the author’s prerogative of having the last word.

First, just to clarify, I understand perfectly well that you’re not…[Read more]

Hi Travis,

We seem to be going in circles, or talking past each other, which is disheartening. Of course, internet message boards aren’t the most subtle medium of communication ever devised, especially when it comes to nuances—perhaps we should convene over a beer at some point to thrash out whatever still needs thrashing out.

But let me have…[Read more]

Hi Ken,

Many thanks for your reply and explanation! I would like to learn more details about your retrocausal theory by reading these two papers.

Best,
Shan

I would say that we should be renouncing local (light-like or subluminal) causation as the explanation of quantum correlations–which Einstein would not like, of course. I think this is part of moving beyond classical thinking, and into a different ‘paradigm’, to use Kuhnian language.

Fair enough! 🙂

And many thanks for all the interesting questions, too.

-K

Let me make it clear that I see no philosophical problems with your favored program for going beyond quantum theory, and I encourage you to pursue it. I’d help you if I were a (better) physicist, and the payoff could be great if it proves successful! I do have an epistemic worry about the extra local beables required by the program: they remind me…[Read more]

I’m probably too close to Einstein’s perspective to be able to objectively answer that last question… But I have a counter question for you: Given that there is just one tiny change you need to make to your story to regain a causal explanation (in my sense), why resist taking it?

Two months ago, in the last iWorkshop, you quoted me saying…[Read more]

I understand quantum theory as a theory that enables us to explain experimental violations of Bell inequalities in a way that appeals to localized conditions whose obtaining causes the localized events recorded in those experiments. So I think it’s appropriate to say quantum theory helps us explain their violation causally. (See my paper posted in…[Read more]

I understand quantum theory as a theory that enables us to explain experimental violations of Bell inequalities in a way that appeals to localized conditions whose obtaining causes the localized events recorded in those experiments. So I think it’s appropriate to say quantum theory helps us explain their violation causally. (See my paper posted in…[Read more]

If I understand you properly, I think I’d put that in the category of “giving up on causal explanations entirely” (which I admit is also an option, but I’d argue that the entire scientific method hinges on not taking it).

The question I’m asking is how to *explain* those very joint probabilities in terms of a spacetime-local-beable ontology.…[Read more]

The nonfactorizablity I was talking about is a property of joint probability distributions (by contrast with the factorizability needed to derive CHSH inequalities in conjunction with the probabilistic independence of the “hidden states” from the choice of subsequent measurement settings—the assumption you reject). If (as I believe) the…[Read more]

Ah yes… I agree, once you allow a non-factorizable ontology, one gets a lot more options. But I was only talking about explanations with *all* of the “beables localized in spacetime”.

And yes, I’m looking for something deeper; the analogy I like to use is that quantum theory is like thermodynamics without knowledge of statistical mechanics.…[Read more]

Thanks, that’s the clarification I was looking for.
Now I’ll have to think more about whether I agree with your answer!

Here’s a more substantial issue.
In your introduction you lay out “the options on the table”, but don’t include the option of a past-common-cause explanation with no superluminal influences but with no beables continuously…[Read more]

Ah, I see the issue. The question is whether the “causal influence” sweeps from Alice to Bob (via the past) or vice-versa. My answer is neither. Together, both of their choices join to causally influence the past and each other’s outcomes.

Here’s a spatial analogy: What causes the exact pattern of normal modes in a laser cavity; does the…[Read more]

Suppose Alice does imagine it could have been different (as I think she should).
My thought was that in the case I described Bob has a case that Alice’s choice had no influence on the chance of his outcome, since (as it happened) he was the one who fixed the joint spin axis in this instance with the result that his outcome had a 50-50 chance of…[Read more]

Hmmm… Interesting. My first reaction is that Alice’s measurement setting is still a causal factor, but of course here I’m heavily influenced by Huw Price and the interventionist account of causality that he advocates.

What makes me pause a bit here is by focusing on *one particular history*, it’s unclear whether I’m still allowed to imagine…[Read more]

Ken,

Thanks, this is very interesting.

Here is a small (corrected!) question. In part of your answer to your own question “Is this model local?” you say “Alice’s measurement settings are certainly a contributing causal factor to the probabilities at Bob’s apparatus”. Suppose in one instance Alice’s vector underwent an anomalous rotation but…[Read more]

Dear Shan,

Thanks for the great question. On “deriving” the Born rule (or Schulman’s anzatz that does the needed work in this paper), you could try wading through my derivation in http://arxiv.org/abs/1301.7012 , but I’m still not totally happy with this account (and indeed I’ve never even submitted it for publication).

More importantly, that…[Read more]