From: Lee Corbin (lcorbin@tsoft.com)
Date: Tue Apr 08 2003 - 00:52:25 MDT
Eliezer writes
> > Yes, even in those million-to-one duplication events I just
> > described, I'd prefer all my duplicates to go to the preferred
> > event. Yet if it's a choice between me *not* getting a duplicate
> > made, and having it made in an inconvenient location, I'll choose
> > the latter. The ratio of outcomes is not the right way to look
> > at this---what is correct is the total run time I get, and that's
> > why probability also is not appropriate.
>
> "Total run time" seems to break down very fast in the presence of either
> MWI or an open cosmos - your total run time is apparently increasing at an
> exponential rate of 10^150 branchings per second, within which a mere
> twofold duplication would scarcely be noticed, or else is simply infinite.
No, I calculate "total run time" under MWI to be the same as the
total measure of the worlds. The branching-process is one thing,
but the term "branching", although used by David Deutsch, sometimes
conveys to people the mistaken impression that new universes come
into being, rather than old universes merely becoming distinguished.
The phrase "consider a group of identical universes" occurs in David
Deutsch's 1997 book "The Fabric of Reality" many times. He uses this
as a starting point whereupon the "group" undergo different events.
(This causes no small number of quite sophisticated people to imagine
that this implies that some members of the group must have already
been different to begin with.)
So whereas my run time does not increase over time, (starting from
a group of identical universes), it does increase incrementally for
each duplicate that gets made. If there is just one original, then
the creation of a duplicate does double the run time I get.
In MWI, on the other hand, my actual run time constantly (and sadly)
diminishes, for in some worlds I will not complete this sentence
either because the valley I live in will be destroyed by an Iraqi
nuclear explosion (oops, sorry, I know how sensitive you are about war-
related threads ;-), or because a certain lamp on a high bookshelf
will fall and knock me unconscious.
> > > I *do* anticipate being in both places. That's *why* I want a move rather
> > > than a copy. I *want* be in the grocery and I anticipate the frustration
> > > of the Eliezer who finds himself still at home. When I snap my fingers I
> > > should just go where I want, dammit!
> >
> > But the *moving* is inferior in most copy scenarios because you get
> > less run time.
>
> "Less run time" seems a remarkably fragile concept. The *relative* amount
> of runtime *this version* of you gets determines the *relative* weighting
> of this present in your past self's future.
That seems right.
> You should care which future versions of you get the most runtime.
Yes. I hope that the versions of me that finish this sentence without
the telephone ringing get the most run time.
> But how can you tell whether your present has a "little" or a "lot"
> of runtime? As far as I can tell, you cannot.
Yeah, the only way that I can even imagine guessing is to wonder about
how probable my (or even our) existence is. I'm especially worried that
my mother was the last of ten children, and my father was fifth of six.
Yet this is a complex topic, because the way I look at who I am, there
are tentacled and tailed versions of me in other worlds that nonetheless
have so much in common with me (recall the bizarre similarities of
identical twins) that we are the same person.
> This leads me to propose that "runtime" is a relative quantity
> used in renormalization of futures, rather than an absolute
> quantity that applies to the present.
>
> (And then he gave a quiet, mysterious smile.)
And I answer in a knowing--yet perhaps partly sardonic--nod and grin.
Lee
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