Re: Many Pasts? Not according to QM...

From: Patrick Leahy <jpl.domain.name.hidden>
Date: Wed, 18 May 2005 19:02:04 +0100 (BST)

On Wed, 18 May 2005, Quentin Anciaux wrote:

> Le Mercredi 18 Mai 2005 17:57, Patrick Leahy a écrit :
>>
>> SNIP
>>
>> Of course, many of you (maybe all) may be defining pasts from an
>> information-theoretic point of view, i.e. by identifying all
>> observer-moments in the multiverse which are equivalent as perceived by
>> the observer; in which case the above point is quite irrelevant. (But you
>> still have to distinguish the different branches to find the total measure
>> for each OM).
>
> Hi,
>
> I thought of Observer Moment as containing the observer... What is the
> meaning of an OM (the same) which spread accross branches ? If you start
> by the assumption that OM are fundamental, then a "branch" is an OM. Or
> a branch is a consistent succession of OM ?
>

I'm also learning a new "language" here as well, so forgive me if I got
it wrong. I was trying to put the best "spin" I could on the idea of
multiple pasts. Personally I'm not sympathetic to the OM concept in the
first place, except as a useful device for anthropic calculations.

By a "branch" I mean a branch of the wave function (Psi for short), which
in MWI does literally have a branching structure in (configuration space +
time). This is absolutely not an OM: for one thing, a branch is extended
in time. Also, each branch of Psi describes a history for all the
observers in the universe (not to mention all the non-self-aware bits),
and hence contains (>>?) billions of OM at any given time. And of course a
different OM for each observer at each moment.

> If the split forever is correct, then does a consciousness spread
> accross all those branch where the OM is in ? or just in one branch, and
> in other branches with the same OM, this is not the same consciousness ?

This is really a matter of definition, I think. Is there a distinction
between "consciousness" and "OM" ? I would say yes but I suspect many
here would disagree. From my point of view, I'd prefer to say that each
observer (and her consciousness) inhabits a specific branch and has only
one past, even if it is indistinguishably different from that of a copy in
another branch.

> If the later, why can it be said that it is in fact the same OM ?
>

I'm with you. But if you take OM as fundamental, as some here do, you
might prefer to re-sort the OMs scattered throughout the multiverse so
that all identical OMs go into one "pot"; then you can choose to call this
pot a single OM with a greater or lesser weight. In which case it is
probably legitimate to talk about these having multiple pasts, though in
another sense they have no past (they are self-contained moments!), only a
memory of one (which is *not* multiple, by definition).
Received on Wed May 18 2005 - 14:09:18 PDT