> On 20 Nov 2019, at 14:51, John Clark <[email protected]> wrote: > > On Wed, Nov 20, 2019 at 12:50 AM Bruce Kellett <[email protected] > <mailto:[email protected]>> wrote: > > >>> I thought one of the attractions of the many worlds theory was that it > >>> was realistic -- in the sense that the wave function really exists a a > >>> physical object, > > >> I don't know where in the world you got that idea. Even probability is > >> pretty abstract but you don't even get that until you take the square of > >> the absolute value of the wave function, which contains imaginary numbers > >> by the way. How much more different from a physical object do you want? > > > I thought that you had read Sean Carroll's recent book and might, > > therefore, have known better than this. On page 32, Carroll writes "First, > > we take the wave function seriously as a direct representation of reality, > > not just a book-keeping device to help us organize our knowledge. We treat > > it as ontological, not epistemic." That is what is meant by wave function > > realism. > > All physicists agree that probabilities and imaginary numbers can help > represent physical objects and the same is true of the wave function, but no > physicist thinks of imaginary numbers or wave functions or probability as > physical objects as you claim. And yes, Carroll treats the wave function as > ontological not epistemic, and yes, to Carroll the wave function is more that > just a bookkeeping device to keep track of what we know and what we don't > know, and yes Carroll gives another correct definition of realism. Many > Worlds theory does NOT say a photon just before it hits a polarizing filter > is in the up or the down polarization and we just don't know which one, it > says it really is in both states, it says a particle is NOT always in one and > only one definite state, it says the world is not realistic. > > >> A theory is realistic if it says a particle is in one and only one > >> definite state both before and after an interaction even if it has not > >> been observed. Many Worlds is about as far from that as you can get. > > > That is not wave function realism as used in many worlds. That version of > > realism is not even applicable to ordinary "text-book" quantum mechanics; > > it is not even Eisteinian realism. > > I have no idea what the difference is between "text-book" realism and > "Eisteinian realism" is and I don't think you do either, in physics there is > just realism and nonrealism. And you don't give any definition of "Realism" > at all, you just say I'm wrong; but Wikipedia agrees with my definition of > the word, it says: > > "Realism is "counterfactual definiteness", the idea that it is possible to > meaningfully describe as definite the result of a measurement which, in fact, > has not been performed (i.e. the ability to assume the existence of objects, > and assign values to their properties, even when they have not been measured).
Yes, that is Einstein’s physical realism. It is implied by Mechanism. It should not be confused with physicalism, which assumes that the only explanation of physical realism is that there is a primary (irreducible) physical reality. With mechanism, the physical realism is entailed by the fact that nobody can change the relative measure on all computations in arithmetic, no more than changing the value of 666. The arithmetical reality makes the physical and statistical “counterfactual definiteness” as solid as 2+2=4, or Ex(x+2=4), without any need of an ontological commitment on some “universe” or “matter”. Bruno > > > I know that you like to play dumb, John, and act the troll. > > So this is your strategy now, if you can't win with the facts or with logic > maybe you can win a battle of the insults. > > John K Clark > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/CAJPayv2kmC7Pf-Nt_%3DFXrWaNcJ6Wwfd9k6hpmkQNdjDYnBhaWw%40mail.gmail.com > > <https://groups.google.com/d/msgid/everything-list/CAJPayv2kmC7Pf-Nt_%3DFXrWaNcJ6Wwfd9k6hpmkQNdjDYnBhaWw%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/C0C9F7B2-290F-4217-B8FA-99CF98D69FE1%40ulb.ac.be.
