On Tuesday, October 15, 2019 at 2:24:10 AM UTC-5, Philip Thrift wrote: > > > > On Monday, October 14, 2019 at 6:52:24 PM UTC-5, Lawrence Crowell wrote: >> >> On Monday, October 14, 2019 at 4:44:42 PM UTC-5, Bruce wrote: >>> >>> On Tue, Oct 15, 2019 at 5:38 AM Philip Thrift <[email protected]> >>> wrote: >>> >>>> On Monday, October 14, 2019 at 1:20:39 PM UTC-5, Brent wrote: >>>>> >>>>> Part of the dislike of the MWI is that its proponents assume a purity >>>>> that is not an evident virtue of the intepretation. For example, >>>>> interpreting the squared amplitudes as probabilities seems to be assumed, >>>>> along with the existence of the preferred basis in which the amplitudes >>>>> are >>>>> defined. Together these are almost the same as CI. If you ask >>>>> "probabilities of what?" in MWI the answer can't be probability of >>>>> existing >>>>> because MWI has committed to all solutions, however improbable, existing. >>>>> >>>>> So it becomes probability of finding yourself in a particular >>>>> world...which >>>>> depends on a theory of consciousness and seems to regress to von Neumann >>>>> and Wigner. >>>>> >>>>> Zurek's envariance attempts to answer these questions and provide a >>>>> justification for preferred bases and what probability refers to. But >>>>> notice that to the extent he succeeds he is justifying taking a simple >>>>> probabilistic view and saying one of those preferred states happens and >>>>> the >>>>> others don't. >>>>> >>>>> Brent >>>>> >>>>> >>>>> >>>> In the single-particle double-slit experiment*, an observer could see a >>>> dot appear anywhere on a screen where path interference does not reduce >>>> the >>>> probability to zero. So with the literal many-world-branching theory, how >>>> many different worlds are produced, each on with its own observer seeing a >>>> dot on the screen? >>>> >>> >>> According to MWI, an infinite number. Each world will have the dot at a >>> different place on the screen. >>> >>> Bruce >>> >> >> What you say may open up a bit of a hole or snag in MWI. This is >> something I have been pondering some since Carroll's popularization. If MWI >> fundamentally preserves unitarity by splitting off worlds then localization >> of a measurement is an illusion.Consider a particle measured somewhere on a >> path from x and x'. The path integral and the nonlocality of paths is a >> sum over all possible measurements in all space containing x and x', then >> there must be a continuum of possible worlds splitting off. If the operator >> has a continuum of eigenvalues *x*|x> = x|x> there must then be a >> continuum of possible worlds if there is indeed no fundamental localization >> with a measurement. This is not just infinite, but uncountably infinite. >> >> This is different from how decoherence maintains unitarity and conserves >> qubits. There a local interaction occurs that induces quantum phase to >> enter into a set of ancillary states or reservoir of states. Then we can >> consider quantum states as finite, but unbounded from above, so that local >> observations and measurements are possible. >> >> This does seem to run into some oddities that either need to be worked >> out or that might indicate some gap in MWI. The persistence of nonlocality >> in MWI is interesting for possible quantum gravitation work. In that case I >> can think of maybe a way around this, where this uncountably infinite set >> of g_{ij} configurations, or Ψ[g_{ij}], can be identified with "exotic" >> manifolds that are removed. It is less clear how this can happen with >> ordinary quantum fields that have local realizations. >> >> LC >> > > > > To mix an analysis (or a theory) of the path integral with an analysis (or > a theory) of MWI is mixing two fundamentally contradictory frameworks that > only leads to confusion. > > @philipthrift >
I am thinking of a path integral as most physicists do, which is an action principle that is a sum over amplitudes or histories. You are thinking according to the quantum interpretation of Dowker and others, which has auxiliary postulates or assumptions. LC -- 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/a744c0ca-784f-4c26-af6f-256c37f5df38%40googlegroups.com.
