In particular, the product dynamics satisfies the “commutativity” axiom, and is therefore almost unique among discrete dynamical theories in **not** creating any obvious problem for special relativity. See my paper for more.

As for why it’s “not seen among the usual quantum interpretations,” I don’t know but can guess. I remember a passage in Bell’s “Speakable and Unspeakable” book where he discussed a similar proposal, comparing it to the creationist belief that the universe was created in 4004 BC with the fossils already in the ground, light from distant stars already headed toward us, etc. If you accept that sort of radical skepticism about the past, then it seems impossible to do science.

For example, suppose you shoot a photon at a half-silvered mirror; then you ought to be able to use the Born rule to calculate the probability that you’ll see the photon fly off in one direction vs. the probability that you’ll see it fly off in the perpendicular direction. According to the product dynamics, however, it’s overwhelmingly more likely that you, the photon, the mirror, and all your records of the experiment will disappear in the next instant, to be replaced by something totally different (but consistent with its own illusory “past” that never actually happened). So you might argue that every time that *doesn’t* happen, we obtain overwhelming experimental evidence that the product dynamics can’t be right. (Though of course, if it *did* happen, then by assumption we wouldn’t remember it! 🙂 )

I was going through your slides from Prof. Preskill’s birthday symposium.

It would take me some work to read them reasonably well, but I already have a question – why is the “product dynamics” picture not seen among the usual quantum interpretations? Of course, it is a most crazy thing, but is THAT a problem?

(That ‘picture’ would not hold true if you take into account special relativity, am I right? You have a pair of bits in (|00> + |11>)/(square root of 2), non-relativistically they could be just two bits assuming ‘0’ and ‘1’ randomly at each instant, only both always in the same (classical) state. But relativistically there are no ‘same instants’ if they are not on top of each other. Is THAT the problem?)

]]>And congratulations to John. Happy birthday-conference!

(It is pleasing to know in person all these great guys.)

]]>