>
> On Wed, 19 May 1999, Russell Standish wrote:
> > What is different between classical mechanics and QM is that in CM you
> > can make statements like "That particle has spin X" independent of
> > what any observer is doing. In QM, you have to take into account what
> > the observer has chosen to do.
>
> Depends what you mean, but there's no real difference. In QM, of
> course, a particle doesn't have a spin; the universe has a wavefunction.
The universe only has a "wavefunction" in the third-person
perspective, which of course none of us can observe.
>
> > [Jacques Mallah wrote]
> > > The predictions of QM do of course depend on the initial
> > > conditions, which determine what the observer will look at. (Or more
> > > generally, the measure distribution of observations.)
> >
> > This is "reductionism ad absurdum", to coin a phrase. No theory can
> > make predictions based on such a fantastic knowledge of initial conditions.
>
> I guess you don't know what the word 'predictions' means in this
> context. Of course no human would be able to gather all the info. That's
> completely irrelevant; it's a thought experiment, and I'm talking about
> the implications that follow in principle from the theory. By definition,
> a deterministic theory predicts everything from the initial conditions.
>
Well the way "predictions" is usually used is what the theory can say
about the environment _given_ imperfect knowledge of the initial conditions.
> > > > > Nature must have a mathematical criterion for it, if it is going
> > > > > to figure in a theory of physics.
> > > >
> > > > Quite agreed. However, I don't believe this to be much of a
> > > > problem. Most mathematical treatments of such take it to be some kind
> > > > of projection operator.
> > >
> > > Then "most mathematical treatments" are not computationalist.
> > > There is in fact no reason to suppose that individual identity is at all
> > > well defined, and the closest that computationalism could come would be to
> > > define it as an implementation of a computation - which would NOT lead to
> > > immortality, since the number of implementations of a given computation
> > > decays with time.
>
> > I'm afraid I've lost you here. I thought we were talking about QM observers.
>
> And I've lost you. We are, as a special case; the above is true
> in general.
>
> > > > > > > - The expected value of your age would be infinite, contrary to
> > > > > > > observations which indicate no unusual age on your part.
> > > >
> > > > This para still indicates that you are falling for this rather absurd
> > > > sampling assumption mentioned above. Give me one good reason why you
> > > > would expect conciousness to sample randomly from the set of all such
> > > > "concious points", rather than in an ordered (and potentially
> > > > unbounded) sequence of self-consistent points (ie a history).
> > >
> > > Are you aware of this entire so-called history? I don't know
> > > about you but I only have one moment of observation to go on - now. Your
> > > talk of random vs. ordered sampling is total nonsense - of course there is
> > > no 'jumping around in time'. It is not a random sampling, it is an
> > > effectively-random sampling, since all the moments of observation
> > > exist.
> >
> > What is the difference between a random sampling and an
> > effectively-random sampling?
>
> Sorry, I thought you had some basic knowledge of the MWI.
> A random sampling would be possible in a non-deterministic theory,
> I suppose with 'minds' as hidden variables. It is not related to what I
> was talking about.
> An effectively random sample occurs when there are many copies
> that exist of similar things. The effective probability that a given copy
> will have some characteristic is the ratio of the number (or more
> generally, the measure) of copies with that characteristic to the total
> number (or measure).
ie it boils down to the same thing with imperfect knowledge of initial
conditions.
> If you know you partial info about one of those things and want to
> make decisions, you should take the Bayesian probability that it will have
> that characteristic to be equal to the effective probability. This is how
> 'probabilities' arise in the deterministic MWI.
>
> > > The fact is that when you have a limited set of information, you
> > > must use the Bayesian proceedure for extropolation. There is no mystery
> > > about it. If you open your door and see a long string lying in the
> > > street, you are unlikely to be right near one end. This in no way implies
> > > that the string has to be chopped up into little pieces.
> >
> > Again, I can see how the SSA can apply to a piece of string viewed
> > from a doorway, but not one's lifetime.
> >
> > > So I do indeed think it is as obvious as, say, 1+1=2. And the so
> > > called 'history', to work as you say, would have to be defined in a way
> > > such that individual identity had a mathematical definition and had
> > > special dualistic laws of physics such that measure was conserved on it as
> > > a function of time, which is ridiculous.
> >
> > I think we've clarified our major source of disagreement. It seems you
> > believe in the strong SSA (as Hal calls it), and I don't. I don't
> > think this should be a matter of belief, however at present I can't
> > think of any better argument against it than Occam's razor, which is
> > not sufficiently strong to convince the true believer. Indeed, it
> > seems you want to throw Occam's razor back at me!
>
> The present situation is not acceptable. Your beliefs and those
> of the other 'q-suiciders' are based on misunderstanding, not on a
> legitimate source of disagreement.
>
I perfectly understand what the strong SSA claims. I simply don't
believe it. In order to support your position, you invoke the strong
SSA. Perhaps you ought to look for another argument that might show
some inconsistency in either of our positions.
> - - - - - - -
> Jacques Mallah (jqm1584.domain.name.hidden)
> Graduate Student / Many Worlder / Devil's Advocate
> "I know what no one else knows" - 'Runaway Train', Soul Asylum
> My URL: http://pages.nyu.edu/~jqm1584/
>
>
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Dr. Russell Standish Director
High Performance Computing Support Unit,
University of NSW Phone 9385 6967
Sydney 2052 Fax 9385 7123
Australia R.Standish.domain.name.hidden
Room 2075, Red Centre
http://parallel.hpc.unsw.edu.au/rks
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Received on Sun May 23 1999 - 23:11:49 PDT