On Mon, Feb 24, 2020 at 11:29 PM Bruno Marchal <marc...@ulb.ac.be> wrote:
> On 23 Feb 2020, at 23:25, Bruce Kellett <bhkellet...@gmail.com> wrote: > > On Mon, Feb 24, 2020 at 12:00 AM Bruno Marchal <marc...@ulb.ac.be> wrote: > >> On 22 Feb 2020, at 05:37, Bruce Kellett <bhkellet...@gmail.com> wrote: >> >> >> I am not sure that I completely understand what Zurek has done here. The >> problem of carrying the initial amplitdues through a sequence of repeated >> trials is opaque to me. >> >> >> It seems to me that this is a direct consequence of the linearity of the >> tensor product. >> >> I interpret for example the 1/sqrt(2) in a superposition as describing an >> infinity of accessible histories, where I can access some particle state >> (and eigenvalue) with a probability one half. If I make a measurement, that >> “1/sqrt(2)” is inherited by the state describing me + that particle. >> >> I me> (1/sqrt(2) a + 1/sqrt(2) b) = 1/sqrt(2) Ime>Ia> + 1/sqrt(2) >> Ime>Ib>. The weigth of a has passed on me, by linearity/unitarity. >> > > Sure, you can write 1/sqrt(2) in front of each term. But the relative > state in each case is the |me>, and that does not depend on the leading > coefficient. > > > Why? With such an interpretation, QM would not work. The relative > coefficients gives the superposition state that you are in. You could as > well say that there is no probabilities in the coin tossing, because each > “history” is independent of all the counterfactuals, but then there is no > more any probabilities at all, anywhere. > QM works by imposing a probabilistic interpretation on these coefficients: the Born rule is an additional assumption, it is not inherent in either collapse theories or Everett many-worlds theories. When you, in a single trial, see |up> (i.e., the state is |me, who sees > up>), how does that depend on the 1/sqrt(2)? > > > Because that 1/sqrt(2) told me in advance that once I consider the wave > of me + the particles, > In the 1p picture, you do not know the coefficient in advance -- you can only infer probabilities from the data obtained in a sequence of trials. belong to that superposition. It explains the probability that I observe, > including if I rotate my experimental device, by trotting differently the > mixture from the pure state. All use of probabilities are based on > some theories. The only problem for Everett is that once he uses mechanism, > he has to extract the wave itself from all computations realised in > arithmetic (i.e. *all* computations, with their complex redundancies, as we > accept the Church-Turing thesis). > > From the first person perspective, remember -- do not mix in your 3p > opinions. > > > That is the whole problem: finding a 3p sharable description of the big > picture which explains the 1p local picture in a way which is coherent with > all the observers experiences and descriptions. > So you admit that you have to mix the 3p and 1p pictures. But in QM we only have access to the 1p perspective. Bruce -- 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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLRO9_G_WG_d4W7uqqCcNuPB1q2qooO9S%3D_4sR1GwfnYXg%40mail.gmail.com.
