Projects
Nonequilibrium systems
Ideas
The statistical concept of entropy is the basis for related criteria
of stability and minimum-bias estimation. Though first shown useful
for equilibrium physical systems, its extensive development in the
theory of communication and computation has shown that entropy methods
are inherently methods of inference, not restricted to any particular
domain or substrate. In principle, entropies can be defined for
non-equilibrium quantum systems, ensembles of histories, and even
evolutionary dynamics -- anywhere a system's internal degrees of
freedom are not fully determined by the constraints on its boundaries
or the laws of its dynamics.
Opening statistical inference to the domain of processes as well as
states leads to the idea of "kinetically constrained ensembles".
Single chemical reactions constrained by quantum bond structure, whole
reaction networks constrained by stoichiometry and reaction rates, and
especially the multi-layered spatial and catalytic systems of
biochemistry are examples of ensembles with kinetic as well as
energetic constraints. Such ensembles can be described
macroscopically by state variables which are currents as well as by
configurations. New kinds of phase transitions can occur in which
fluxes are the order parameters. If the emergence of life took place
through a series of dynamical phase transitions in driven
geochemistry, non-equilibrium entropy methods may provide a way to
explain the emergence and subsequent stability of the biosphere.
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