On Wed, 18 May 2005, Quentin Anciaux wrote:
Le Mercredi 18 Mai 2005 17:57, Patrick Leahy a écrit :
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).
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).