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\'3;↓↓\FFS\F2
\'3;↓Q\CSTANFORD UNIVERSITY
\F3\CSTANFORD, CALIFORNIA 94305
\F4


ARTIFICIAL INTELLIGENCE LABORATORY\←L\-R\/'7;\+R\→.\→S   Telephone:
COMPUTER SCIENCE DEPARTMENT\←S\→.415-497-4430
\F0\C18 October 1974


Bernard M. Oliver
Research and Development
Hewlett-Packard Company
1501 Page Mill Road
Palo Alto, California 94304

Dear Barney:

\J	Thanks for the draft of your comments on O'Neill.  I have no
comments on it yet not having had time to read it in detail, but
when I thought about it previously, I got even higher costs for his
scheme than you did.

	Here is a beginning of a counter-fantasy - the austere space
colony.  Liquidating Hewlett-Packard would just about pay for it.
The part about how much steel is required to contain the air is calculated
by equating pdV for a small expansion of a sphere with tadA where
t is the tensile strength, a is the wall thickness and A = 4πr\F32\F0
is the area of the steel sphere.  I suppose that it is not legitimate
to identify the t of that kind of expansion with the tensile strength
of the steel made into a bar, but I didn't know what else to do.  The
rest of the numbers are total guesses except the part about the chickens.
A chicken grows to four pounds from an egg in seven or eight weeks,
so assuming you can live on a chicken a day and that the chicken
grows linearly, person requires a biomass of (56 days) \F1times\F0
(2 pounds of chicken) = 112 pounds.  The rest depends on how fast
you can recycle the human waste, the chicken droppings, and the chicken
feathers and bones back into something the chlorella can use.  The
chlorella themselves can double their mass in half an hour, so you
don't have to keep much of that around to feed the chickens.
Naturally, it would be nice to have other food sources around to provide
variety; they only have to average the same mass-efficiency.  Eating
the chlorella directly would be very efficient.

	Any comments or help in elaboration of the austere space colony
would be welcome.

	I suppose there is a 30% probability that the social system will
get oppressive enough in the next 30 years that there will be a need
for it.\.
\←L\→S\←R\-L\/'2;\+L\→L
Best regards,




John McCarthy
Director, Artificial Intelligence Laboratory
Computer Science Department
\←S\→L

\JP.S. The \F1Project Independence\F0
statement was well received and Stanford has got
a number of requests for it mainly from companies concerned with
energy.\.

JMC;paw
oliver.le1[let,jmc]:SU-AI