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> Date: Tue, 18 May 1999 20:13:45 -0400
> From: Jacques M Mallah <jqm1584.domain.name.hidden>
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> Subject: spooky?
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> On Mon, 17 May 1999, Russell Standish wrote:
> > > > It is hardly nonsense. The predictions can easily depend of the
> > > > 'picture' but must be consistent with each other. Let me give a simple
> > > > example:
> > > >
> > > > In one picture, observer A decides to measure the spin of an electron
> > > > in the x direction. In the other, observer B decides to measure the
> > > > spin of the electron in the y direction. Observer A will see the spin
> > > > of the electron aligned with x axis, and Observer B will see it
> > > > aligned with the y axis. Both observations are correct in the first
> > > > person picture of that observer. A "person" with the third person
> > > > perspective, sees observers A and B as inhabiting separate `worlds' of
> > > > a multiverse, each with appropriate measure that can be computed from
> > > > Quantum Mechanics.
> > >
> > > On the contrary, this is a textbook example of the way I said it
> > > works. The theory predicts some measure distribution of observers; an
> > > individual observer sees an observation drawn from that distribution.
> > > There are no different sets of predictions for different pictures, just
> > > the measure distribution and the sample from it.
> >
> > It sounds to me like you don't think the prediction changes according
> > to what the observer chooses to observe? An electron cannot have its
> > spin aligned with the x axis and the y axis at the same time. Once the
> > experimenter has chosen which direction to measure the spin, the
> > history of that particular is observer is constrained by that fact,
> > and the predictions of QM altered accordingly. This is true both in
> > MWI and the Copenhagen interpretation, and is the "spooky" nature of QM.
>
> That's no different from the situation in classical mechanics. Of
> course an observer does not really have free will; he will do what he does
> because that's what the equations of physics say for his initial
> conditions. The only "spooky" thing about QM was the alleged collapse of
> the wavefunction upon "observation", which in Copenhagen seems to give the
> "observer" a special physical power. This is not the case for the MWI,
> and the MWI is not "spooky" unless you count the fact that other you-like
> beings must exist.
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.
> 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.
> In QM, of course, it's certainly true that if an observer or other
> object becomes entangled with a system in a specific way, the time
> evolution would be different than if a different entanglement had
> occurred. Trivial and unrelated to your previous fallacy, which involved
> not different physical observations but different ways of analyzing the
> SAME physical situation.
In MWI, the same physical situation corresponds to a number of
observers entangled with the system in every way possible. The third
person view sums over all the observers, and one has conventional QM
with various probability distributions as predictions. Take any one
entangled observer, and you have a first person view. You may chose to
call these all different physical systems if you like, but most people
would beg to differ.
In classical mechanics, of course, the observer does not get entangled
with the system, hence everything is one and the same.
>
> > > > > A theory predicts some measure distribution on the space of
> > > > > conscious observations. From the point of view of an observer, you see
> > > > > one observation drawn from that measure distribution.
> > > > > If measure were conserved for a particular individual as a
> > > > > function of time, you immediately have 2 problems:
> > > > > - How to define a particular individual? You need to, or else the
> > > > > measure of other people would count too, and would stay relatively
> > > > > constant as opposed to the rapidly diminishing measure of "you".
> > > >
> > > > This is a furphy. I have no problem whatsoever in knowing that I am
> > > > who I am. If you are unsure of your identity, then that's your problem.
> > >
> > > 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.
> > > > > - 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?
> 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!
> Computationalism, by contrast, suggests that measure is
> proportional to the number of implementations of each conscious
> computation, which is not conserved.
>
> - - - - - - -
> 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 Tue May 18 1999 - 18:27:17 PDT