Re: poly: Von Neuman Culture density functions

From: Hal Finney <>
Date: Tue Dec 16 1997 - 09:21:53 PST

Eugene Leitl, <>, writes:
> Fermi's Paradoxon is telling us so many things that it tells us exactly
> nothing.

I'm not sure it's as uninformative as that. You list many possible
explanations but reject several of them as unlikely. I think some of
the others can be rejected or merged, too.

> Life nucleation density is damn near zero. (Clearly it takes second- and
> third-generation stellar system for the proper kind of chemistry to host
> life. However, if there's a race into space the visibility threshold
> uncertainty lies in several MYrs range, which should be very visible if
> there are any within our lightcone).
> Our extrapolations are wrong: life quite never makes it into space. Great
> Filters Galore -- there are too many possibilities to screw up for
> comfort. All hail to Malthus.

For those who haven't seen it, Robin Hanson's essay at discusses the question of
why no spacefaring civilizations seem to exist, and the implications for
our own prospects. (I think the term "Great Filter" is Robin's coinage,
based on David Brin's "Great Silence".)

> Life's out there, but it's invisible. Efficiency demands it to operate at
> few K scale. (Ditto for superenergetic life).

Even so, you would expect life to expand to fill niches. Obviously there
are unfilled niches around, namely our own planet and other planets in
the solar system, and probably other solar systems.

> Life is not out there anymore, because it has transcended. This assumes
> leaving this universe is a piece of cake. Heartening, but insufficient
> data.

This also violates niche-filling.

> We're an experiment; an altruistic Superentity has generated Aleph-x
> life-supporting Petri-dish designer universes shorty before it attained
> nirvana (Omega, whatever). This is religion, not science.

Even for this, I think Perry's original claim could be said to hold
true. Suppose the whole universe *is* an experiment. Well, we still have
the question of why there are no other civilizations visible within
the universe. Presumably it's because there are no others.

> We live in a zoo, everything's a fake. Imo, for the hypothetical
> Super-Potyomkin we are not interesting enough by far. Also smacks strongly
> of religion.

We could be in a virtual reality simulation, or even have our whole
solar system enclosed in a shell of projectors to produce an image of
an unpopulated universe. (The latter sounds like a big job, but maybe
in the "real" universe outside, resources are more abundant than in the
empty universe they choose to show us.)

Even so, the simulated or virtual universe is itself unpopulated, and
within the framework of the simulation Perry's reasoning is still valid.
None of us can say anything about what might be happening outside the
universe. (And it's not so easy to define what it means for the universe
to be real vs simulated, either.)

I still think Perry's original claim, that there are no other advanced,
technological lifeforms within the visible universe, is the most likely
conclusion based on what we see.

Received on Tue Dec 16 17:32:29 1997

This archive was generated by hypermail 2.1.8 : Tue Mar 07 2006 - 14:45:29 PST