Georges Quenot wrote: > > [...] > I would be interested in reading the opinions of the participants > about that point and about the sense that could be given to the > question of what "happens" (in the simulated universe) in any non- > synchronous simulation "when" the simulation diverges ?
Thanks for the replies. Until now I feel a bit confuse with them, possibly because I do not have an appropriate idea of what is meant exactly by "computable" and/or by what accounts for a simulation of the universe. I probably have some naive intuition about them. So maybe it would help to clarify some points: By computable, is by default assumed something like physically computable using current or future technologies or only formally computable (possibly considering virtual computers containing very much more memory locations than there are particles in the visible universe and for computation times very much longer than the actual age of the universe) ? In the latter case, does the memory of the computer need to be finite or can it be considered as unlimited ? Do the simulation has to end within a finite time or can the simulated universe be something like an asymptotic state of its description in a given formalism ? Alternatively or in other words, could the simulated universe be in some way the limit of a series of approximations computed with increasing available memories and computation times ? Is "computable" relative to the universe as a (spatio-temporal) whole or only to given supbarts of it ? Also I feel some confusion between the questions "Is the universe computable ?" and "Is the universe actually 'being' computed ?". What links do the participants see between them ? Finally, what link is there between the computability of the universe and the possibility of its exact description in the context of arithmetic ? Maybe too many questions for a single post. I didn't go through the whole archive and there might well be already answers to most of these so I welcome any reference to appropriate previous posts. By the way, are there some FAQs about these questions ? Georges.