"Last-minute" vs. "anticipatory" quantum immortality

From: Jesse Mazer <lasermazer.domain.name.hidden>
Date: Wed, 12 Nov 2003 04:34:27 -0500

>From: Bruno Marchal <marchal.domain.name.hidden>
>To: everything-list.domain.name.hidden
>Subject: Re: Fw: Quantum accident survivor
>Date: Sat, 08 Nov 2003 15:56:31 +0100
>At 14:36 07/11/03 -0800, Hal Finney wrote:
>>Well, I do believe in continuity of consciousness, modulo the issues
>>of measure. That is, I think some continuations would be more likely to
>>be experienced than others. For example, if you started up 9 computers
>>each running one copy of me (all running the same program so they stay
>>in sync), and one computer running a different copy of me, my current
>>theory is that I would expect to experience the first version with 90%
>Almost OK, but perhaps false if you put *the measure* on the (infinite)
>computations going through those states. I mean, if the 9 computers
>running one copy of you just stop (in some absolute way I ask you to
>conceive for
>the benefit of the argument), and if the one computer running the
>different copy, instead of stopping, is multiplied eventually into many
>self-distinguishable copies of you, then putting the measure on the
>histories should
>make you expect to experience (and memorized) the second version more
>It is the idea I like to summarize in the following diagram:
>\ / | |
> \ / | |
> \/ = | |
> | | |
> | | |
>That is, it is like a "future" bifurcation enhances your present measure.
>It is why I think comp confirms Deutsch idea that QM branching is really
>QM differentiation. What do you think? I mean, do you conceive that the
>measure could be put only on the "maximal" possible computations?

This is an important point which I think people often miss about the QTI. It
is sometimes spoken of as if the QTI only goes into effect at the moment you
are about to die (and thus have no successor observer-moment), which would
often require some fantastically improbable escape, like quantum tunneling
away from a nearby nuclear explosion. But if later bifurcations can effect
the first-person probability of earlier ones, this need not be the case.

Consider this thought experiment. Two presidential candidates, let's say
Wesley Clark and George W. Bush, are going to be running against each other
in the presidential election. Two months before the election, I step into a
machine that destructively scans me and recreates two copies in different
locations--one copy will appear in a room with a portrait of George W. on
the wall, the other copy will appear in a room with a portrait of Wesley
Clark. The usual interpretation of first-person probabilities is that, all
other things being equal, as the scanner begins to activate I should expect
a 50% chance that the next thing I see will be the portrait of George W.
appearing before me, and a 50% chance that it will be Wesley Clark.

But suppose all other things are *not* equal--an additional part of the
plan, which I have agreed to, is that following the election, the copy who
appeared in the room with the winning candidate will be duplicated 999
times, while the copy who appeared in the room with the losing candidate
will not experience any further duplications. Thus, at any time after the
election, 999 out of 1000 versions of me who are "descended" from the
original who first stepped into the duplication machine two months before
the election will remember appearing in the room with the candidate who
ended up winning, while only 1 out of 1000 will remember appearing in the
room with the losing candidate.

The "last minute" theory of quantum immortality is based on the idea that
first-person probabilities are based solely on the observer-moments that
qualify as immediate successors to my current observer-moment, and this idea
suggests that as I step into the duplication machine two months before the
election, I should expect a 50% chance of appearing in the room with the
portrait of the candidate who goes on to win the election. But as Bruno
suggests, an alternate theory is that later bifurcations should be taken to
influence the first-person probabilities of earlier bifurcations--under this
"anticipatory" theory, I should expect only a 1 out of 1000 chance that I
will appear in the room with the portrait of the losing candidate. This
would lead to a weird sort of "first-person precognition", where after the
duplication but before the election, I'd have good reason to believe (from a
first-person point of view) that I could predict the outcome with a high
probability of being right. But this kind of prediction would be useless
from a third-person point of view, since all outside observers would see two
symmetrical copies who both seem equally certain that their candidate will
be the winner. Of course this is not much stranger than the basic quantum
immortality idea that if I am in some dangerous accident, most third-person
observers will see me end up dead, while I have a close to 100% chance of
surviving from a first-person POV.

Applied to quantum immortality, this "anticipatory" idea suggests it would
not be as if the universe is allowing events to go any which way right up
until something is about to kill me, and then it steps in with some
miraculous coincidence which saves me; instead, it would be more like the
universe would constantly be nudging the my first-person probabilities in
favor of branches where I don't face any dangerous accidents which require
"miracles" in the first place. Of course since this would just be a
probabilistic effect, I might still occasionally face accidents where I had
to be very lucky to survive, but the lower the probability there is of
surviving a particular type of accident, the less likely I am to experience
events leading up to such an accident.

Jesse Mazer

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Received on Wed Nov 12 2003 - 04:36:41 PST

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