June 28, 2010

Many-Worlds Incoherence

First, I understand how thinkers felt driven to MWI to avoid what they considered an otherwise insoluble (?) quantum measurement problem. But MWI is IMHO grossly fallacious and full of hand-waving snow-jobbery. The honest way is to admit we can't solve something, not to put forth a fallacious pretense because many thinkers just can't stand the alternatives. The key difficulty is in way things "split" and the attitude towards why and how we find quantum statistics. What we find is statistics, not a superposition of states. The statistics are based on squared amplitudes.*

So how does MWI deal with that? Well suppose there are two states, showing amplitudes: 0.6i |1> + 0.8 |2>. (Sometime I'll get around to improving the symbols here.)  When we look we find either |1> or 2>, at respective probabilities 36% and 64%. But we started with two states, and no statistics. In WMI, neither states just "goes away" and the true outcome in the mulitverse  has no preference - hence no genuine statistics of e.g. a real card game (heh, well a "real card game" as we imagine it in a classical world or collapsian world!) But there "are" only two states, even if we keep both and just somehow decouple them from each other. How oh how to get 36% of one outcome and 64% of the other? A mere split wouldn't do the trick, since I'd have equal chance of ending up in either outcome. After all, the amplitudes are just intensities, not actual sets of things. (And if they were, how many would there be in each set? Some arbitrary number? But if infinite such as Aleph null, no way to have the ratio.)

So the MWIers double-talked their way into some mystical, inexplicable sort of thickness of the wavefunction that somehow stands in for real statistics (like, authentic frequentism) that they call "measure."  Everett imagined that one's "subjective probability" of ending up in a world depending on this "depth" (which BTW is not the amplitude, but its square.) We see an illustration on p. 172 of the silly and fawning book Schrödinger's Rabbits by Colin Bruce. Huh? That's just doubletalk. What the heck is that? If there's no unique self but both states |1> and |2> continue to evolve, then it isn't like the chance that one "self" will end up in world A or world B. They can't explain what they mean by that. Real quantum experiments do build up patterns the same as are generated by classical sources of unique outcomes.

Furthermore, this sort of "measure" is not the authentic probability measure in statistics. Maybe that fools readers about MWI into thinking a sort of inherent, hand-waving mystical equivalent of real probability (of how many of one v. the other) is mathematically rigorous and kosher. But I can't see any way to explicate the phony MWI "measure" and explain what's it's proponents claim is going on. For example, in Rabbits we see this quote:
"He has his own take on the question, does measure require large, maybe infinite numbers of each world-line to generate the correct probability ratios. For him, measure has no more meaning than it is postulated to have. You could perhaps (very loosely) think of it as a kind of tag attached to each world-line with a percentage value written on it, but certainly not in terms of huge stacks of each world-line."
Huh? A "tag" in which you just wave a wand and say "there aren't really more of one than the other, but it's as if there were." How?! This is an abomination, it's intellectual irresponsibility.

Another big complaint I have about MWI is about where in the chain of events, does the separation of states come about? Briefly here, I may have more later: In MWI, observation is not special. So, that juncture should not be the specific instigation of the separating of the states. Now consider a Mach-Zehnder Interferometer with photon entering and "splitting" at BS1. So shouldn't the photon state "separate" at the first beamsplitter instead of after recombining at BS2? Why not? That's supposedly a choice between taking the lower leg or the upper leg, isn't it? But if that happened, then the lower and upper paths are "separated" - so why should they be able to interfere later?  Yet we know there's interference.  I realize that issues of of decoherence complicate that, but it's food for thought. (I also have big gripes about the idea that decoherence explains collapse. Read more elsewhere on this blog, or Google for decoherence + "circular argument."

Schrödinger's Cat is still wanted, dead and alive. Reports of his liberation from uncertainty are greatly exaggerated.  Is there an answer?  I don't think so. I believe the universe is just not always amenable to our modeling hopes and capabilities.  We should have the humbleness to accept that could be the case.  It sure beats coming up with disingenuous "models."

*(Well, squared moduli, but the complex numbers just show relative phase. We can represent phases between real AC currents with complex numbers if we want to, it doesn't suggest anything about how "real" the currents are or not. So it's a canard to say "the WFs aren't real, because they "are represented" by complex numbers. Uh, no - not "are represented", that's just a choice. And if the WFs aren't real, what the hell is really there?)


June 27, 2010

Marcelo Gleiser Has a Point

This post is based on my comment at Backreaction, under Marcelo Gleiser's guest post explaining it may be a mistake to pursue a final theory of "the" universe (or at least, to think it must be simple/beautiful etc.)  I think Marcelo has a good point.  Here I delve into the relevant and deep philosophical problems about "why is there something instead of nothing" and "why is it like this and not otherwise."  (We should add: is "something" even clearly defined - a point well made by the modal realists.)

We don't have any a priori notion of why "reality" should be like this or otherwise. For deep logical reason I've noted before, I don't see how we can. There is nothing in logical analysis that can "bless" some mathematical constructs with a "right to life" over others - ie, to be incarnate in the special manner we feel that we are. To be, as Madonna put it, "living in a material world." (I like to say, it's like number 23 specially existing also as brass numerals "just because", despite being just another number ...)

Many thinkers cogently argue we can't even make that distinction. I think that collides with our basic feeling of being alive etc. but it is near impregnable as a strict logical critique of material realism being coherently distinct from abstractly descriptive and totally unselective modal realism.

Hence some believe in MUH: that all structures in the Platonic mindscape exist (logically wide-open, a far bigger set than even the wildest string-theory landscape etc.) If so there is little point in looking for a fundamental theory that makes sense or is beautiful etc, because we are just in a possible world that allows us to exist.

However, that presents deep Bayesian expectation problems. If that were true, our greatest expectation would be living in a universe just orderly enough to get us in this condition and to this point, and no more so (because there are so many more ways to do that than to be very neatly consistent, with identical electrons and laws that don't change over time etc. in various odd ways.)

So no one knows what's going on or why it should be or be like this. I think there's some "management" in the sense some ultimate reality has some intrinsic goals or even purposes like beauty and life-friendliness, but it would be wrong to impose that as a working assumption.  BTW that would not have to be like a person, FWIW.  So: find a TOE that works if you want, but be aware of the logical problem of justifying it existentially.

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