> von Neumann 'proof' (as i recollect it) that we are alone in
> the universe, goes something like this:
>
> If other life exists there is no reason to assume that it
> came to technical competence at exactly the same time as
> we did. In fact, given the lifetime of the universe, it
> would have likely gotten its space legs long ago.
> If they could, they would have built self replicating
> machines to explore space. These machines would have very
> quickly (in galatic terms) become ubiquitous in the galaxy
> (i don't remember if he generalized to the universe or not)
> and we would have observed them by now. Since we don't we
> must be alone.
>
> I apologize for the poor quality of the above quote, but i
> think it more or less conveys von Neumanns argument. Note
> that it has a number of assumptions in it... (i have no
> intentions of defending the above 'proof').
The difference between 'conjecture' and 'proof' is sometimes hazy. The
above is excellent reasoning for 'we are alone in the universe' as a
conjecture.
Let me tear it apart as follows:
1st) Plausible.
2nd) Plausible, under a correctly-implemented theory of evolution.
3rd) This requires certain anthropomorphisms about the psychology of the
candidate other life. I don't know which ones. It also presumes the
technical civilization didn't self-destruct first. [Larry Niven has
discussed both points in 'N-Space'.]
4th) This presumes a vaguely intelligent choice of raw materials, plus
semi-intellgient positioning. This is plausible, given the 3rd
assumption.
This is a complete demonstration of a conjecture, but utterly useless as a
proof. I would hope the word-substitution was inflicted by someone else.
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/ Kenneth Boyd
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