>
> I'm not sure this is a fruitful line of inquiry if nobody can think of any
> reason why there might ever be a cul-de-sac branch. Furthermore, the idea of
> a 'cul-de-sac-branch implies an observer-moment without an observer. I'm
> confident that there is no such thing.
Its not quite devoid of meaning. Cul de sac branches may have
observers in the case where reverse causality doesn't apply, and these
observers really would die ie not experience immortality. Still, there
is probably little further use of discussion until someone comes up
with a convincing scenario for a cul-de-sac branch.
>
> > -----Original Message-----
> > From: Russell Standish [SMTP:R.Standish.domain.name.hidden]
> > Sent: Friday, August 20, 1999 1:22 AM
> > To: dude.domain.name.hidden
> > Cc: everything-list.domain.name.hidden
> > Subject: Re: zombie wives
> >
> > >
> > >
> > >
> > > Russell Standish wrote:
> > > >
> > > > >
> > > > > 4. Subjective probabilities can be computed on the basis of the
> > > > > Strong SSA, and we get
> > > > > P(H, t1) = 1/2
> > > > > P(H, t2) = P(H, t3) = 2/3
> > > > > If this is the case, then I think we have to throw Tegmark's
> > > > > scheme using Bayesian statistics out the window. This option
> > > > > has severe metaphysical problems, though, in my opinion. I
> > > > > think Hal was saying, in his post, either this option, or
> > > > > option 1 above, but I'm not sure.
> > > > >
> > > > > 5. Subjective probabilities can be computed, and we should expect
> > > > > the common-sense results
> > > > > P(H, t1) = 1/2
> > > > > P(H, t2) = P(H, t3) = 1/2
> > > > >
> > > > > It's a fair coin, after all, right?
> > > > > I think this gets Gilles' and Bruno's vote (and Russell's?)
> > > > >
> > > > > 6. Subjective probabilities can be computed, and we should expect
> > > > > the nonsensical results
> > > > > P(H, t1) = 2/3
> > > > > P(H, t2) = P(H, t3) = 2/3
> > > > >
> > > >
> > > > If the probabilities can be computed, then compute them. I have
> > > > computed the probabilities as being 1/2,1/2. If you compute them as
> > > > 1/3,2/3, then you need to advance a similar computation, and then for
> > > > good measure, show me where I erred. Probability calculations are
> > > > notorious for their subtleties, so I won't take offence at being shown
> > > > wrong. At present, the only argument I can see that gives the
> > > > probabilities as 1/3,2/3 is the one based on the strong SSA - (your
> > > > point 4) - an assumption that I reject.
> > >
> > > Clearly there is not enough information to simply "compute" the
> > > probabilities from Jane's subjective perspective, without making
> > > some additional assumptions. In your computation, you assume that
> > > the measure of each branch is unaffected by its future evolution.
> >
> > True - but I think this is currently a pretty fair assumption.
> >
> >
> > >
> > >
> > > > A reverse causality type of argument would assume that you would never
> > > > enter branches that have no escape routes. I have toyed with this
> > > > idea, but reject it - principally because I have yet to see an example
> > > > of a branch with no escape route, so in essence it becomes
> > > > meaningless
> > >
> > > This makes no sense to me. Let's rewind it -- You have yet to see a
> > > branch with no escape route. Fine, I haven't either. Let's assume
> > there
> > > are none. The reverse causality argument would assume that you never
> > > enter branches that have no escape routes. Fine, we've just assumed
> > that
> > > there are none. So what's the problem?
> > >
> > >
> > > >, but if there were such brances - my belief in foward
> > > > causality is so strong, I would prefer to question quantum
> > > > immortality, than to invoke reverse causality as a way of salvaging
> > > > QI.
> > >
> > > Yes, I guess I've been trying to make the point that QTI implies reverse
> > > causality. I think it does.
> > >
> >
> > Yes - but only if cul-de-sac branches exist. My point is that QTI is
> > not proven, and shouln't be assumed to be true. Existence of
> > cul-de-sac branches + absence of reverse causality would imply QTI is
> > false.
> >
> > >
> > >
> > > --
> > > Chris Maloney
> > > http://www.chrismaloney.com
> > >
> > > "Donuts are so sweet and tasty."
> > > -- Homer Simpson
> > >
> > >
> >
> >
> >
> > --------------------------------------------------------------------------
> > --
> > Dr. Russell Standish Director
> > High Performance Computing Support Unit,
> > University of NSW Phone 9385 6967
> > Sydney 2052 Fax 9385 6965
> > Australia R.Standish.domain.name.hidden
> > Room 2075, Red Centre http://parallel.hpc.unsw.edu.au/rks
> > --------------------------------------------------------------------------
> > --
>
>
----------------------------------------------------------------------------
Dr. Russell Standish Director
High Performance Computing Support Unit,
University of NSW Phone 9385 6967
Sydney 2052 Fax 9385 6965
Australia R.Standish.domain.name.hidden
Room 2075, Red Centre
http://parallel.hpc.unsw.edu.au/rks
----------------------------------------------------------------------------
Received on Fri Aug 20 1999 - 19:19:00 PDT