Indeed, I've always thought there was a dubious assumption there. There isn't a universal time to pace the clock tics of a simulation. Relativity forbids it. Anyway, time is a subjective illusion.

Back to the question: So what happens when the simulation "diverges" from regularity? Some possibilities: a) The universe ends b) Pink elephants pop up everywhere c) It's already happening I like (c) ----- Original Message ----- From: "Georges Quenot" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, January 06, 2004 8:32 AM Subject: Is the universe computable? > I start from a part of this post from David Barrett-Lennard (Mon, > 3 Nov 2003 19:48:49) but I could probably hev selected several > similar other ones: > > > Given the "source code" for the simulation of our universe, it would > > seem to be possible to add some extra instructions that test for a > > certain condition to be met in order to tamper with the simulation. > > It would seem likely that there will exist simulations that match our > > own up to a certain point in time, but then diverge. Eg it is > > possible for a simulation to have a rule that an object will suddenly > > manifestitself at a particular time and place. The simulated conscious > > beings in such a universe would be surprised to find that induction > > fails at the moment the simulation diverges. > > It seems to me that there is a very strong assupmtion here which > is that there should be some synchronicity between the "time" in the > postulated computer into which the universe would be simulated and > the time inside that simulated universe (as this is typically the > case when an electronic device is simulated). > > But such an assumption not only does not seem necessary in any way > but it also does not seem possibly consistent (or it would be very > arbitrary at least) with a universe like ours for what we know of > the implications of general relativity (it does not seem possible > to define any global time in any consistent way in our universe). > > Many other way of simulating the universe could be considered like > for instance a 4D mesh (if we simplify by considering only general > relativity; there is no reason for the approach not being possible in > an even more general way) representing a universe taken as a whole > in its spatio-temporal aspect. The mesh would be refined at each > iteration. The relation between the time in the computer and the time > in the universe would not be a synchrony but a refinement of the > resolution of the time (and space) in the simulated universe as the > time in the computer increases. > > Alternatively (though both views are not necessarily exclusive), one > could use a variational formulation instead of a partial derivative > formulation in order to describe/build the universe leading again to > a construction in which the time in the computer is not related at > all to the time in the simulated universe. > > It seems to me finally that the simulations in which there is a > synchrony between the time in this universe and the time in the > computer simulating it are very specific (if even existing) among > all other possible simulations of the same universe (at least > for the kind of relativistic universe we live in). I would even > conjecture that the measure of the set of synchronous simulations > is null within the set of all possible simulations of a given (not > so trivial) universe (if one can give a sound sense to this). > > 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 ? > > Georges. >