[ExI] QT and SR

[The Avantguardian]

--- On Mon, 9/15/08, Lee Corbin <lcorbin at rawbw.com> wrote:

> If you believe SR, then how can you believe
> "instantaneous"
> wave-function collapse? (Even if somehow that bizarre
> idea becomes coherent, which almost no one claims it is.)

Because SR is a theory about physics, Lee, and a wave function has no physical existence. It is a mathematical abstraction and a mathematical abstraction can undergo a mathematical operation at any speed it needs to.

For example, imagine an incredibly large finite integer as a binary string that is 10^46 bits long. Now imagine I add 1 to that integer, what happens? That huge binary string grows by a single bit which becomes a 1, while the other 10^46 bits become zeroes:

{11111 . . . 10^46 . . . 11111} + {1} = {10000 . . . 10^46+1 . . .00000}

How long did that take?

Now imagine that that binary string of ones is written in the tiniest font imaginable -- merely one Planck length wide. Written on space-time, the big binary integer would stretch the distance between Earth and the Sun. So now when I add a 1 to it, an additional 1 bit gets added to the end of the string near the sun and the rest of the bits from the earth to the sun become zeroes. . . instaneously! Even though if Superman used his supervision to watch that distant bit change, he would have to wait 8 long minutes for the information to arrive.

If arithmetic addition can carry faster than light, than a wave function can collapse faster than light. And I don't mind the instantaneous collapse of a wavefunction any more than than I do of getting hit over the head with a probability density. 

> But when the Mississippi splits into two separate streams,
> is any conservation law broken? Likewise, at the delta
> where it splits into innumerable streams, no conservation
> laws are broken because the entire flow of water is still
> the same, merely broken into discrete channels.

Yes, but the amount of water flowing in each channel is diminished. What gets diminished in the separated universes? 

> But if  
> It's the same on MWI branching. The "measure"
> of two
> separate streams, when added, equals the measure of
> the single undistinguished branch before splitting.

What is the "measure"? What SI unit is it in?

> Then these each break into two, and then those into two,
> and
> finally we have the upper limit of 32 possible
> "branches" or
> universes. Let's examine the one which is 10011.
> Suppose that
> it now bifurcates into 10011 and 11011. That merely makes
> it merge with a pre-existing 11011, i.e., become identical
> with.
> This is analogous to interference.

I don't doubt that MWI is explanatory and I am sure the math comes out perfect. I simply doubt it is necessary to create new universes just to forget them except in the rare instance that the results of an experiment call for the universes to merge again.

> (It's this last
> "merging"
> process that I myself find so weird. It doesn't work
> unless the
> two beams are nearly perfectly set up so that the two beams
> are in exactly the same phase, and even then, the
> probability
> of merging is quantum-mechanical, and falls off if the
> beams
> are ever so little out of phase.)

I find it weird too. And if I have mechanistic problems with the split, then I have even more problems about the "merge". Do the Lagoliers eat the extra universe? How do the proper two universes find each other to merge? What happens if a Swiss physicist on the other side of the planet splits his own beam before the presumably American physicist in your example gets his split beams back in phase enough to merge them back together? Which alternate universe does the American physicist merge with?

> >>    *It is only the strong quantum interference
> >>    between the various paths taken by charged
> >>    particles in parallel universes* that prevents
> >>    such catastrophes and makes solid matter
> possible.
> >
> > Well this certainly begs the anthropic principle. Talk
> about balancing on a razor's edge.
> 
> I don't follow.

I was just saying that if we owe the stability of our universe to "interference" between the parallel universes *and* the diligent split occuring in a timely fashion, then it's a precarious existence we lead. How does MWI time the disappearence of all the extra matter-energy when two universe "merge" again? That's far more problematic than simply erecting an impenetrable barrier between universes at the speed of light.  

> > But Copenhagen is already a seething jumble of massive
> > interference everywhere. MWI is putting that seething
> > jumble into a funhouse hall of mirrors. Although to be
> honest,
> > the implications of MWI in a finite universe are very
> bizzare.
> 
> They don't seem so to me, not at least from what
> you've said.

Oh, just wait. ;-)

> I urge you to read "The Fabric of Reality" and
> get the full
> force of Deutsch's descriptions of the "shadow
> photons".
> It seems likely to me that you'll agree that
> Everett's MWI
> is the simplest idea anyone has ever thought of to account
> for them.

Admittedly, I have never read Deutsch. "Shadow photons"? That sounds an aweful lot like an antiparticle of light. Bosons are supposed to be their own antiparticle. Besides, Lee, you have explained MWI to me far better than anyone has explained it to me before. I doubt Deutsch could do it better. And I don't even know for sure that it is wrong, since it gives the right answers. I just don't like the Langoliers and the magic glue.

> Yeah, but it's not copying, only branching. And
> although
> MWI is "extravagent on universes", it employs one
> fewer
> principle than CI or other theories like it. Namely, there
> is no "collapse" postuate. So the number of
> *principles*
> is reduced. An analogy might be that although Newton [...wrote...] 
> *one* nice principle with tremendous explanatory
> power. You no longer need a deity to arrange the movements
> of the stars and planets and so on.

No, you just need one to split an infinite universe an infinite times a second and keep track of all the branches on the off chance that some quantum physicist somewhere decides to fine tune his interferometer so that those same two branches can again be merged.

> > Another issue I have with MWI is computional
> complexity.
> > First off, an infinite universe, immediately rules out
> any
> > simulation-type theories. Turing machines are defined
> to
> > have a finite number of states. I hope you realize
> that an
> > infinite universe cannot have a finite number of
> states.
> 
> Good point. This is one implication of MWI I had not
> thought
> about.
> 
> On the other hand, on p. 211 of "The Fabric of
> Reality", Deutsch
> is completely definite about the number of universes (i.e.
> branches)
> being on the order of the continuum. So that's not
> merely a
> *countable* infinity at all. We're already at
> aleph-one. So any
> more splitting isn't conceptually problematical at that
> point,
> (when things are already about as "worse" as they
> can get).

But this is my point exactly. Infinity is a mathematical treasure-trove and MWI treats it like a waste dump for unnecessary universes.

> > Therefore an infinite universe can neither be a turing
> machine
> > nor be simulated on one.
> 
> Well---nice point again. Hmm, actually that's maybe one
> less
> thing to worry about   :-)

Yes, until one starts to wonder what could be keeping track of the transfinite aleph-1 universes out there so that only the right ones get merged. If it's not a Turing machine, what is it?
Furthermore, if the universe really is aleph-1 infinite, then it never really splits and instead of calling it the "Many Worlds Interpretation" they should call it the "Single Hairy World Interpretation".

> > And you really don't want to know what MWI in a
> finite universe
> > implies. It's not just swallowing a bullet; its
> swallowing a cannonball. ;-)

> When I think back to my five bit example, it doesn't
> seem so
> rough to me.  Well, yes, on that analogy it is 32 times as
> "complicated" with 32 times as many things
> "going on",
> while in Copenhagen, 10011 either goes to 10011 or 11011
> with a 50/50 chance, so less storage and I guess less
> calculation
> is involved (it being a lot easier to keep track of 5 bits
> than 32).
> You're right about that.

Well, Lee, if you still believe in MWI or SHWI in an infinite universe, I can't prove you wrong by math or logic. Being extravagent with universes in an infinite multiverse is just as correct as saying that the planet Jupiter does backflips in the sky if one is extravagent with fictitious forces. That's the beauty of relativity:

If they were goddesses, the Earth could claim that the Moon is tidally locked to her. The Moon for her part could claim that the Earth orbits her in a lunar-stationary orbit. Einstein would have to throw up his hands and say they were both right.

But if you would indulge MWI in a finite universe, then contemplate my cannonball:

List all the physical processes you know of whereby complex systems with no outside intervention can replicate themselves, with only minor differences between copies, at an exponential rate. I can only think of one.


Stuart LaForge

"See them clamber, these nimble apes!  They clamber over one another, and thus scuffle into the mud and the abyss."- Friedrich Nietzsche