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The Gaia hypothesis, which perceives our
planet as a complex self-regulating living organism, originated from
the speculations of James Lovelock1 when employed as a
NASA consultant on matters relevant to the search for life on Mars.
From his research, Lovelock reasoned that there was
really no need to go to a planet to look for life that was anything
like life on Earth. All that was necessary was to get a spectrum of
the light reflected through the atmosphere of any planet to detect
whether or not the atmosphere was in thermodynamic equilibrium.
The atmosphere of a planet like Earth with an oxygen
content of approximately twenty percent, is in a highly improbable
state that could not be sustained by normal geological and physical
processes. Lovelock decided that there must be some extraordinary
process involved for any planet that sustains an atmosphere far from
its thermodynamic equilibrium. Hence any such eventuality should be
an indicator for life on a planet. Since the atmospheres of both
Mars and Venus were very close to their equilibrium value, Lovelock
concluded they must be lifeless.
From this original limited speculation, the Gaia
hypothesis has been expanded by many to include not only the Earth,
but also galaxies and even the whole universe to the state of being
vibrant, self-regulating, self-sustaining living organisms.
This
extremism has brought disrepute upon the Gaia hypothesis which
nevertheless has much to commend it--provided we stick with science
and recognize these untestable speculations for what they are.
The incredibly complex role of life in the
self-regulation of non-equilibrium states for our atmosphere in
respect to oxygen, carbon dioxide, moisture, temperature, light
absorption and reflectance, etc., is well documented even
though not completely understood. The effects of life extend far
beyond the atmosphere, and even without the unwise undertakings of
human beings, living organisms often have large and drastic effects
upon the "normal" physical processes on land, ocean and
air.
An interesting situation has been unveiled over the
last two or three decades with respect to the self-regulation of
galaxies, particularly spiral galaxies like the Milky Way.2
One entirely unexpected discovery was that the inner
and outer stars of these galaxies rotate around their center at
about the same speed. Hence stars at the outskirts take a lot longer
to complete a revolution than those further in.
When this was discovered, it was reasonably simple to
calculate that the mass of a galaxy was quite inadequate to hold it
together through gravitation. One conclusion--to date the solitary
one conceivable--is that we "see" only a small portion of
the galaxy, about 80% or more of its mass being invisible to us.
This invisible mass has the name "dark matter.3"
A further surprise, still not well known outside of
astronomy circles, is that the spirals arms that we see in
photographs of these galaxies actually rotate independently of the
galaxy and its stars. Hence they are better thought of as
"waves of motion" through the galaxy that cause some stars
to become much more visible as the "wave" passes
through their region.
As further information came to light, it began to be
appreciated that a spiral galaxy is a highly stable, self-regulating
system that sustains itself in a state far from thermodynamic
equilibrium. Its spiral arms are also recognized as the main
location where new stars are being born.
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