On Thu, Jan 9, 2014 at 12:58 PM, John Clark <johnkcl...@gmail.com> wrote:

> On Wed, Jan 8, 2014 at 7:11 PM, LizR <lizj...@gmail.com> wrote: > > > The equations of Newtonian dynamics are time-symmetric, >> > > I know. > > > similarly for relativity both SR and GR - >> > > I know > > > and quantum mechanics is, too. >> > > I know. > > > The only thing in the entirety f physics that isn't based on time >> symmetric equations is thermodynamics, >> > > That and the equations of cosmology. And astrophysics. And meteorology. > And [...] > <http://groups.google.com/group/everything-list> What "equations of cosmology" are there besides the equations of general relativity, used to model the entire universe? In general it's true that in some cases scientists use separate equations derived from observation to deal with large-scale phenomena, as in climate modeling. However, it is always assumed that reductionism holds, that the behavior of any large-scale system ultimately emerges statistically from the interaction of all its basic parts evolving according to more fundamental laws (as has been shown to be true of thermodynamic laws in statistical mechanics), even if in some cases it may be too difficult in practice to derive the higher-level equations from the fundamental ones (but it is possible for other cases besides thermodynamics, for example the interactions of certain molecules, normally the domain of chemistry, can be derived from basic quantum rules alone, as with the model of interacting water molecules discussed at http://www.udel.edu/PR/UDaily/2007/mar/water030207.html ). Do you disagree with "reductionism" in this sense? Are you suggesting that any equations governing higher-level systems are irreducible even in principle to lower-level laws (plus initial conditions or other boundary conditions)? 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.