On Wed, Jan 8, 2014 at 1:47 PM, John Clark <johnkcl...@gmail.com> wrote:
> > On Tue, Jan 7, 2014 at 1:24 PM, Jesse Mazer <laserma...@gmail.com> wrote: > > > you could have laws where a large number of initial states can all lead >> to the same final state (many cellular automata work this way, specifically >> all the ones whose rules are not "reversible"--for example, in the "Game of >> Life" >> > > Yes that's what irreversible means, there is more than one way to get into > a given state. > > > there are many initial states you can choose that will lead all the >> black squares to eventually disappear and leave you with all white >> squares). >> > > Sometimes the Game of Life ends up oscillating between 2 states, but the > only time it enters a final state is when all the cells have died. > Sometimes you might end up with a oscillation between the initial state and > some other state but all those examples are trivial and very small (such > as 3 cells in a straight line). Sometimes the Life pattern just keeps on > growing forever, and sometimes the Life pattern can emulate a Turing > Machine. The laws of physics, that is to say the rules of the cellular > automation, are identical in all these examples, but the initial conditions > are different. > > If the laws of physics actually make a change in something (and they are > pretty lame laws if they don't) and if the initial conditions of the > universe were very low entropy, and if there are more ways to be > disorganized than organized (and there are) then any change those laws of > physics make will almost certainly lead to a increase in entropy. > > John K Clark > OK then, do you agree with the point I was making that deriving the second law requires conservation of phase space volume (which can be guaranteed by choosing reversible laws, I think)? If your laws allow for the possibility that an ensemble of initial microstates occupying a large volume of phase space can converge on a smaller set of final microstates occupying a smaller volume, then one can choose one's macrostates in such a way that high-entropy initial macrostates are more likely to lead to low-entropy final macrostates--do you disagree? For example, in Life one could define macrostates in terms of the ratio of white to black cells, and quite a lot of initial microstates that are in the macrostate of a 50:50 ratio of black and white (where the number of possible combinations is huge) end up in a later macrostate where the cells are wholly or almost wholly white (with a much smaller number of possible microstates, and thus a lower entropy). Jesse -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
