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∂AIL Dr. Richard Goody↓American Academy of Arts and Sciences
↓165 Allandale Street↓Jamaica Plain Station↓Boston MA 02130∞
.<<(617)522-2400>>
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Dear Dr. Goody:

	The following remarks are suggested by your joint memorandum
with Michael McElroy and Philip Morrison.  I would
like to be informed of future developments towards an Academy
study of the issues and might like to take part.

	Looked at from the point of view of the future of humanity,
space exploration and colonization has two important aspects:

	1. The dispersion of humanity will help prevent its
extermination by catastrophe - whether this catastrophe be a
nuclear war, some kind of environmental disaster, or a natural
disaster.

	2. It will also help prevent the domination of humanity
by any single ideology - whether this ideology be communism,
capitalism or environmentalism.

	From the point of view of individuals or groups, there are other
considerations:

	1. Some, who hope to reform humanity, look with horror on
people with bad ideas escaping control.  The Soviet position on
space treaties seems to express such an attitude and many who propose
to confine mankind to the earth until we can be sure we won't
contaminate the universe have a similar point of view - no doubt
with somewhat different ideas about what shouldn't be permitted
to get a foothold in space.  I can't be sure of your own position;
it seems to be predicated on centralized control of mankind's
activities in space, but this may only be a reflection of the fact
that the most substantial activities of the very near future require
so much government support.

	My own position is to encourage diversity to the extent
of permitting secession of government sponsored colonies and permitting the
formation of new colonies that owe no allegiance to any government
on the earth or to the U.N. or any successor to it.

	2. Those who fear disaster on earth - natural, environmental,
war, or political - will want a means of escape.  True escape,
given the power of weapons based on present science, may require
multi-generation expeditions leaving the solar system.  It seems
that present science would support a technology for such expeditions
leaving as early as the end of the present century, although postponed
expeditions would arrive at their destinations sooner.

	I have written a manuscript about this deriving a formula

	%2t = 2 s%D2/3%* p%D-1/3%*%1

where %2s%1 is the distance to a goal, ⊗t is the time required to
reach it, and ⊗p is the figure of merit of the power system in
watts per kilogram.  The system uses a power source (e.g. a fission
reactor) to expel a working fluid (e.g. in the form of ions or other charged
particles) at an exhaust velocity that varies optimally during the
journey.  Nearby stars are reached in the low thousands of years, and
because of the factor %2p%D-1/3%*%1, improving the technology doesn't
change the answers qualitatively.

	Of course, interstellar escape in the next few hundred years
unless there is an advance in science, will be of interest only if
a group feels rather desperate, but there may be such groups if
mankind evolves towards ideological monopoly.

	Anyhow, most of our attention should be devoted to the
exploration and colonization of our own solar system.

	I am somewhat surprised that your memorandum didn't mention
the controversies surrounding the proposed moon treaty as prototypical of
issues that will arise.

	Your remarks about self-reproducing artificial systems suggest the
comment that such a system can be regarded as a limiting case of increased
flexible automation.  A system that manufactures new components for
itself according to computer programs written and controlled by humans
only needs a new top-level program to become a self-reproducing
machine.  However, there seems to be little advantage to us in making
the system entirely independent, and there is especially little
advantage in having it split up into independent self-controlled
units.

	Let me re-iterate my interest in taking part in Academy
discussions.  You will find me an advocate of the idea that humanism
requires tolerating and encouraging diversity in solar system
exploration and exploitation.

.sgn