On Sun, 30 Mar 2008 18:20:29 -0700 (PDT), Brian Davis
> Curious. What are they basing this on? Things like
> "take advantage of frequency where the tensity is the
> greatest" (green, for our Sun... oops, looks like
> evolution missed that)? It would seem so much depends
> on what first photoactive pigment gets fixed into the
> system that there's an awful lot of good old
> evolutionary luck in there. Not to mention there's
> going to be some frequencies that biology would have
> intense trouble tapping (it's tough to fix energy when
> the incoming energy is enough to break covalent bonds,
> for instance).
>
> What's your take on it - worth the read, or rehashing
> the wrong?
My take on it was that it was full of bunkum.
It is evident that the system used by our green plants
(green because they waste the dominant frequency) is an
elaborate overly complicated and inefficient arrangement
resulting from the accidents of history.
In addition to wasting the frequency at which energy is
most abundant, they make a two step reaction using two
photons, when a single photon of red light provides
enough energy to do the reaction in one step.
The theory explaining this that I find plausible is that
the first photosynthesizers used hydrogen sulfide and
absorbed green light. The photosynthesizers at the
bottom were short of green light, and short of hydrogen
sulfide, so they used red light to synthesize a
substitute for hydrogen sulfide, leading eventually to
the two stage reaction used by today's green plants.
If today's earthly plants use a cumbersome, overly
complicated, and ludicrously inefficient photosynthetic
path, as seems the to be the case, then there is no
telling what the color of alien vegetation is likely to
be.
If earthly vegetation was optimally efficient, it would
use every photon that provided sufficient energy to
drive the reaction, other than those that were too
energetic and might damage the photosynthetic machinery.
It would therefore reflect light of low frequency and
high frequency and absorb a broad band around the middle
- thus would most likely look dark purple or dark red.
--
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We have the right to defend ourselves and our property, because
of the kind of animals that we are. True law derives from this
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James A. Donald
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