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)?


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