Jan Harms
Mon, 07 Jul 2008 16:33:48 -0700
Please substitute in my last post: "this does stay in conflict" by "this does NOT stay in conflict"!! Jan Harms schrieb: > Hello Brent, > > perhaps one remark concerning your understanding of "einselection". > Please correct me if I am wrong here, but einselection - which is as you > say related to decoherence - is not selecting one state out of a > superposition of states, but selecting a certain basis in a Hilbert > space. The corresponding basis states are usually what we experience as > classical states. So it serves as an explanation why the world appears > as it is. However, this does stay in conflict with Everett's > relative-state multiverse theory. Instead, einselection is something > heavily required to make multiverse theories a serious candidate of QM > foundation. The only thing which may eventually undermine the beautiful > QM multiverse theory is, that someone discovers a nonlinear effect > inherent to the Schrödinger equation, which hasn't been discovered yet, > because it acts on an incredible small timescale. > > Jan > > Brent Meeker schrieb: > >> Ronald Held wrote: >> >> >>> I am giving a talk on the Multiverse to Star Trek fans in several >>> weeks. I would appreciate any advice and suggestions, since as of now, >>> I have an outline based on Tegmark's four levels. >>> >>> >>> >> One thing I would avoid is presenting the multiverse (of any level) as the >> latest "gee-whiz, science has discovered that..." It is interesting >> speculative metaphysics. Good fodder for SciFi fans but not yet science. I >> cringe when Scientific American or the L.A. Times or some other popular >> publication takes scientific speculation and hypes it as though it were a >> new revelation of science. It happens most often in medical stories, but >> also in physics and astronomy pieces. In the end I think it debases >> science in the popular mind as just more advertising hype and spin noise. >> >> ISTM there were several independent threads that lead to different ideas of >> the multiverse: >> >> 1) The apparent inherent randomness of QM inconsistent with "hidden >> variables" which made the "collapse of the wave function" mysterious and ad >> hoc. The led Everett to argue for a relative-state interpretation which >> implied the QM-multiverse. However, theories of einselection based on >> decoherence and perhaps weak anthropic selection may undermine the >> QM-multiverse. In this theory there is really only one universe but each >> of us consists of multiple branches on which different values are projected. >> >> 2) Completely independent of (1), development of theories of cosmogony >> based on quasi-classical quantum gravity showed the universe could arise >> from "nothing". These theories naturally have the consequence that >> arbitrarily many other universes could also have arisen. Any natural >> process is repeatable. This theory of multiverses allows that universes >> exist with different values of those physical constants that seem arbitrary >> in our current theories (a set that could change). These universes all >> exist in the same sense this universe exists, they may even have common >> points (e.g. in singularities). Again some anthropic selection principle >> must be invoke to explain *this* universe. >> >> 3) The extremely abstract nature of physics has led naturally to the >> speculation that only the mathematics matters. We seem to know nothing >> about elementary particles and the interior of black holes beyond the >> mathematics they satisfy. So perhaps it is only the relational properties >> of information coded into the mathematics that is the ur-stuff of the >> world. In that case all possible information structures may be considered >> equally "existent". This also fits with the idea that reality can be >> simulated. If reality consists in the relation of information, it doesn't >> matter how that information is embodied or maybe that it is embodied at >> all. Therefore reality may *be* a simulation - as on the holodeck of the >> Enterprise. >> >> 4) Finally, what seems to have motivated Tegmark and also perhaps Bruno and >> others is Wheeler's question, "What makes them fly?" Why is one set >> equations instantiated in the world and others are not? Why is there some >> special property of "existing" that some possibilities have and others >> don't. Tegmark sidesteps the question by answering that they are all >> instantiated; so "to exist" is simply to be the subject of propositions >> that form a non-self contradictory set. Starting from this he then must >> try to recover some explanatory power by limiting what we experience by >> appealing to some anthropic principle. >> >> Brent Meeker >> >> >> >> > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [EMAIL PROTECTED] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---