structure of living organisms arises as the consequence of
energy flow, and is strongly reminiscent of the non-equilibrium
phase transitions that can take place in physicochemical systems
far from thermodynamic equilibrium. This organized space-time
structure suggests that both quasi-equilibrium and non-equilibrium
descriptions are applicable to living systems, depending on
the characteristic times and volumes of the processes involved.”
Separate from the world, we are yet inextricably
connected to it. What is the nature of this relationship? What is
the nature of self? In this section we seek the roots of real-world
complexity, including the origins of physiology and selves from nonliving
systems. A transition from noncoherent, molecule-to-molecule heat
transfer to coherent convection occurs in some heated fluids. During
the process more than 1022 molecules come into concert. From a statistical
point of view, this is ridiculously improbable. Yet the coherence
arises naturally from an applied temperature gradient. Nature creates
systems, sometimes quite complex ones, "in
order to" get rid of gradients and export atomic chaos into
the surroundings. "Centripetal," selflike structures
arise from material cycles, energy-driven, self-reinforcing networks.
Despite the term selfish genes, genes do not have selves:
true selves are cells; without proteins and metabolic networks
of recursive amino acids and intermediary molecules, genes are
impotent, no more "selfish" than
an unplugged toaster.
Thermodynamic selfhood comes from dissipative systems that establish
boundaries. Far from sealing themselves off from the outside world, their
boundaries allow them to continue their operations. Biological selfhood
on Earth depends on the semipermeable layer, the ubiquitous lipid cell
membrane, which provides a place, at first microscopic, for expansion
of nonequilibrium processes. Less complex swirling systems grow and even
seem to reproduce without biochemistry, or even chemistry.
Almost perfectly hexagonal Bénard cells are not chemical reactions
or biological life but simple physical processes driven by a temperature
gradient. If Early's priests had seen one of these systems, they might
have sworn it, too, was alive. The Bénard instability is a complexity
driven by thermodynamic processes, not whirling computer disk drives.
Bénard's little experiment had big implications. Although the
intermolecular distances of whale oil are on the order of 10<min>8
centimeter, the liquid resolved into organized structures 0.1 centimeter
in size: a simple heat gradient brings some hundred billion billion
(1020) molecules into lockstep. They line up, show coherent motion.
Such correlation among molecular trajectories and speeds are striking.
They would neither appear nor be predicted in an isolated system. But
these systems do not occur in an isolated system. They occur within
the organizing confines of a gradient.
Open systems naturally compute answers
to the thermodynamic problem of how to come to equilibrium. If we do not
see the organized context, the gradients around such structures, we
will be mystified. The Bénard instability does not come from
a vacuum or a creator. Rather, it works out a previous improbability.
It manifests in concentrated form the differentiation it helps destroy.
A, Bénard-Rayleigh convection in a rectangular container. In Bénard-Rayleigh
experiments a lid touches the upper surface of the working fluid. Bénard
experiments have air as their upper surface. Here counter-rotating convection
with sausage-shaped forms align themselves with the shorter side of the rectangular
container. B, Bénard-Rayleigh convection in a 20-centimeter-diameter
circular dish with silicone oil 0.765 centimeter thick. These rolls go to the
bottom of the heated dish. Each roll is 0.65 centimeter across. Here are billions
of molecules spontaneously forming a coherent macroscopic pattern and process
to dissipate a heat gradient. C, Square Bénard-Rayleigh convection
cells under a glass lid in a square container. The shape of the container determines
the form or the pattern in Bénard-Rayleigh convection. (Photographs courtesy
of L. Koschmieder.)
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II: The Complex
8. Swirl World
9. Physics' Own "Organisms"
10. Whirlpools and Weather
A set of Bénard cells.
In this experiment Koschmieder
(1991) used a 1.9-millimeter-deep layer of silicone oil in a 10.5-centimeter-diameter
dish. The silicone is under a 0.4-millimeter-thick layer of air, which
is under a uniformly cooled sapphire lid. The cells average 0.625 centimeter
across, with hundreds of millions of molecules in a highly organized process
making up macroscopic dynamic structures. The process is initiated from
warm soft spots in the oil surface that give rise to surface-tension effects,
and from convection with hot material rising at the center of the cell.
The oil is heated from below and rises in the center of the cells, cooling
at the cell surface and sinking along the outside edges of the cells. There
is no chemical or biological process involved in these steady-state structures.
(Photograph courtesy of L. Koschmieder
A Bénard system going from linear to nonlinear
states, from conduction to convection. The fluid inside the container is
heated from below, and the top of the apparatus acts as a cold sink. The
temperature profiles inside the apparatus change from an equilibrium isothermal
state of molecular chaos in A,
to a conductive state in B and a convective state in C. Once
heat is applied to the bottom of the system, all the dissipation (in this case
heat flow, Q) occurs via conduction and molecule-to-molecule interaction.
When the gradient reaches a critical value, a transition to convection occurs.
The more the system moves away from the equilibrium state, the more exergy is
destroyed, the system produces more entropy, and more work is needed to maintain
the system in a nonequilibrium state. In D the heat flow Q or
dissipation through a Bénard cell is plotted against the gradient applied
to the system. Of interest is the abrupt transition from conduction to convection
at the critical threshold. Once the system is "organized" via convection,
it has higher dissipation-heat flow rates. (Adapted from Schneider and Kay 1994b.)