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∂AIL Professor John Holdren↓Energy and Resource Program↓University of California
↓Building T4 Room 100↓Berkeley, California 94720∞

Dear Professor Holdren:

	The discussion did not mainly concern the issues raised in
%2Population, Resources and Environment%1 or I would have criticized
points more central to the argument of that book.

	It is presumably a fact of observation that there is more mass in
the lower stages of the ecological pyramid.  That this is not a
consequence of the laws of thermodynamics or some other branch of science
means that we can hope to invert as much of this pyramid as we need to.
In fact, the man-chicken part of the pyramid is already inverted although
the man-steer part is not.  In so far as you have made your readers
believe that this is impossible, you have prevented them from inventing
ways for accomplishing it.

	A thought on thermodynamic restrictions on the use of low
grade ores.  The second law of thermodynamics requires an expenditure
of energy proportional to minus the logarithm of the concentration of the
ore.  I wondered if this makes the extraction  of uranium from sea
water uneconomic.  Calculation shows that it isn't much of a difficulty;
namely, there is more energy in an atom of uranium than the second
law requires for its extraction from 10%511%1 galaxies of 10%511%1
suns apiece.  One must therefore think about what the actual difficulties
are with low grade ores and not just hand wave about the laws of
thermodynamics.

	Your letter shows that the misstatement was not
a slip but a scientific moral lapse.  You and Ehrlich seem to think
that in making a point to an audience, it is legitimate to use whatever
arguments will convince most of that audience - even if the argument
isn't correct.  It regards physics as a branch of rhetoric.
My rhetorical reason for raising the issue was to suggest that if you
use inaccurate arguments in physics, one
can expect even less objectivity in economics and ecology.

.sgn

P.S. Further thought suggests that large parts of the ecological pyramid
supporting humans are already inverted or close to it.  A human eats his
weight in 50 or 60 days.  Therefore, any crop that is almost all food and
reaches maturity in less than 100 to 120 days, has a biomass not larger
than the human mass it supports.  This may be true of high yield rice
which is often triple-cropped, and it could be true of carrots, radishes
or even potatoes.  Of course, inverting the pyramid is not anyone's
objective in itself, but it may be a by-product of high yield short season
objectives.  Should we ever go to %2chlorellae%1 or the like for human
food or even animal fodder, we may well have a highly inverted pyramid.