Re: The difference between organism and ecosystem...

[Leo Caves <***>]

Dan,

a rag-bag reply:

sorry I do not have a PDF of the Ian Stewart article (I had a quick 
google to no avail).

The "gravitational system" in this context is an n-body systems of 
masses in three-dimensional space.  No general exact analytical 
(integrable) solutions of the equations exist for n > 2.   Some special 
cases are soluble: planar motion (ie. restricting degrees of freedom) 
or decoupling the mass of one of the bodies etc.
Of course, you can solve these systems numerically...
(NB: It was Poincare's work on this system, which ultimately led to 
dynamical systems theory and chaos.)

You are right to bring Prigogine into play here as he brought the 
treatment of thermodynamics from equilibrium to non-equilibrium systems 
(so beautifully encapsulated in the title of his book "From being to 
becoming")

Leo

--
Leo Caves, Computational Biology, University of York
http://www.york.ac.uk/biology/staff/lsdc.htm