On 2/25/2015 7:11 PM, Jason Resch wrote:
On Wed, Feb 25, 2015 at 5:28 AM, Bruce Kellett <[email protected] <mailto:[email protected]>> wrote:Bruno Marchal wrote: On 24 Feb 2015, at 22:52, Bruce Kellett wrote: MWI simply formalizes the fact that such data are "in-principle unknowable". Well, usually we say that the SWE formalizes that fact, and that the MWI interpret this in term of many world. But I am OK with your statement, as SWE implies formally the MWI, Statements like this are gaining in currency these days, but this is strictly false. The SWE operating on vectors in Hilbert space does not formally imply the MWI. All that the formalism implies is the existence of superpositions. Schroedinger realized this very early on, hence his example of the cat being in a superposition of dead and alive states. Schroedinger thought this was effectively a reductio ad absurdum for the wave equation.I'm not so sure. I think he was more attacking the role of the observer in creating reality. We see Einstein affirm this in a letter to Schrodinger:Einstein was most impressed with Schrödinger's paper, and in 1950 wrote Schrödinger a letter of praise, saying “You are the only contemporary physicist, besides Laue, who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gunpowder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.”Further, we see that later in his life, Schrodinger began to take his theory (and the reality of the super position) more seriously:“Schrödinger also”, David Deutsch notes, “had the basic idea of parallel universes shortly before Everett, but he didn't publish it. He mentioned it in a lecture in Dublin, in which he predicted that the audience would think he was crazy. Isn't that a strange assertion coming from a Nobel Prize winner—that he feared being considered crazy for claiming that his equation, the one that he won the Nobel Prize for, might be true.” In order to get MWI one has to add a lot more superstructure. In particular one has to solve the basis problem and give a plausible account of the meaning of probabilities in a theory in which every possible result actually occurs. Both of these areas are still matters of substantial debate.Tegmark shows in a large enough world, even under something like the CI, you can't escape "all possibilities being realized", so you're faced with the same probability "problem" whether you think the wave function collapses or not: http://arxiv.org/abs/1008.1066We study the quantum measurement problem in the context of an infinite, statistically uniform space, as could be generated by eternal inflation. It has recently been argued that when identical copies of a quantum measurement system exist, the standard projection operators and Born rule method for calculating probabilities must be supplemented by estimates of relative frequencies of observers. We argue that an infinite space actually renders the Born rule redundant, by physically realizing all outcomes of a quantum measurement in different regions, with relative frequencies given by the square of the wave function amplitudes. if we define world by a structure of events close for interaction. Then, using the FPI, we have a dterlministic and local account of why the data appears for the observer first person (plural) point of view as unknowable, indeterminist and non local. Maybe the data appear indeterministic and unpredictable in principle because they really are that way -- the world is governed by probabilistic laws. We don't actually need all the superstructure of MWI. What do you find more appealing, elegant, and historically more likely to be true: 1. A large number of objects implied to exist by a simpler theory 2. A small or singular number of objects as described by a more complex theoryMW is just what's left over when you dispense with the ill-conceived and ill-defined notion of collapse: the only phenomenon in all science that's not time-symmetric, not time-reversible, nonlinear, discontinuous, non-deterministic, non-local, and observer dependent. I'll take the many worlds before I take that.
But without solving the measure and basis problem, MWI doesn't predict anything - or more accurately, it predicts everything. It simply pretends to dispense with collapse while sneaking in its equivalent in order to use the Born rule. It is radically non-local. There are plenty of phenomenon in science that are non-linear. Computationalism is also discontinuous. Self-localization in FPI is observer dependent; but whatever theory adopted it needs to save the phenomenon of observation. Quantum bayesianism is directly a theory of observation.
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