Le 30-nov.-06, à 08:10, Maurice (for-list) wrote : > It was hoped by some that the study of quantum gravity might deliver > something along these lines. > This may be the wrong place to ask, but does anyone know if string > theory and so on offer any hope in this direction?

Interesting question. I have related questions. Take "loop gravity" (the main competitor of string theory for the marriage between GR and QM). In loop gravity, the GR idea that gravity force = curvature of space is kept all along, so that quantization of gravity leads to quantization of space and time. So there exists, in loop gravity, atoms of space time, and so the physical reality is eventually completely discrete, except for the complex quantum wave amplitudes. Now we can also replace the use of complex numbers by gaussian integers (a+bi with a and b in the set of integers or rationals or algebraical). Due to the linearity of the SWE, this is "mathematically" enough. But then such a loop gravity theory would entail that the number of worlds (of the MWI) are always finite (unless we posit at the start some infinite "Garden of Eden). In that sense String Theory is more coherent with both the comp hyp in the cognitive science and David Deutsch view that the splitting/differentiation is a multiplication by 2^aleph_0 (the continuum). Now about the many world in String theory I remember having read by Witten that the wave aspect of the string theory is not yet well worked out, but a priori, given that string theory is entirely based on the quantum theory (without collapse, it seems to me), the MW should fit in without much problem. Sometimes I think that string theory will even lead to a MW with a vengeance, that nature tries not just all consistent histories, but tries all number systems as well (like the p-adic fields, finite fields, etc.) and all possible topologies, in which those consistent histories can be implemented. Don't know... I have another question: could a quantum chaotical system (as far as we know what that is) be turing universal? Any comments are welcome. Bruno http://iridia.ulb.ac.be/~marchal/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com 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 -~----------~----~----~----~------~----~------~--~---