Caption: The Sun-space-biosphere (SSB) system.
Overall the SSB system is NOT in thermodynamic equilibrium and is NOT quasistatic. However, the component subsystems are one or the other if they defined small enough: small enough layers of the Sun, small enough layers of the Earth's atmosphere, small enough parts of living living organisms, etc.
One can understand and analyze the SSB system by considering the energy flows between the component subsystems. Each flow tends to increase entropy overall.
The short version analysis of the SSB system:
- The 2nd law of thermodynamics
states that a
closed system
(thermodynamics)
will increase in entropy
until it reaches
maximum entropy
which is the state of
thermodynamic equilibrium.
The closed system
(thermodynamics)
will NOT evolve further.
At the macroscopic scale,
it has reached a timeless state which CANNOT support
life.
- Life
requires an
open system
(thermodynamics)
with inputs of LOW entropy
energy in order to sustain
the continuing cycles of
life:
respiration,
the circulatory system,
metabolism,
the circadian rhythm
reproduction,
evolution,
etc.
- Of course, to remain in steady state and NOT heat up, all the
LOW entropy
energy
that enters the
open system
(thermodynamics)
must leave in the form of
HIGH entropy
energy.
- In the case of the
Earth's
biosphere,
the
LOW entropy
energy input is
sunlight
(which is mainly
in the
visible band (fiducial range 0.4--0.7 μm))
and the HIGH
entropy
energy output is
mainly infrared light (0.7 μm -- 0.1 cm)
radiated by Earth
including the Earth's atmosphere.
- Actually, describing the
energy as LOW or
HIGH
entropy is tricky in this case
of the energy flow from Sun
via Earth to
interstellar space
because one does NOT have
thermodynamic equilibrium states
all along the energy flow path.
Suffice it to say that
the photons are low
entropy in the
Sun where they are at high density
(i.e., highly ordered) and
HIGH entropy when they escape from
the Earth to
interstellar space
where they are at low density
(i.e., highly disordered).
Image link: Itself.
Local file: local link: disequilibrium_life.html.
File: Biology file: disequilibrium_life.html.