On Mon, Feb 24, 2020 at 11:29 PM Bruno Marchal <[email protected]> wrote:
> On 23 Feb 2020, at 23:25, Bruce Kellett <[email protected]> wrote: > > On Mon, Feb 24, 2020 at 12:00 AM Bruno Marchal <[email protected]> wrote: > >> On 22 Feb 2020, at 05:37, Bruce Kellett <[email protected]> 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 [email protected]. 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.
