From: alexboko (alexboko@umich.edu)
Date: Tue Mar 07 2006 - 15:30:53 MST
How long is the time window during which a civilization relies on
powerful radio broadcasts for communication before upgrading to cable
and/or narrow-beam methods? There could be a high-tech civilization on
Alpha Centauri for all we know, but either still in that long pre-radio
phase that occupied most of our own history, or in a post-radio phase
and not doing anything else we would notice from a distance.
Phillip Huggan wrote:
> The simplest refutation of SA is that it is either evil, or as Eliezer
> said pointless. You would in effect be playing a child's game for a
> human lifetime.
>
> A Fermi Paradox refutation is that life is probably too rare for
> another technological civilization to exist in the universe, let alone
> our own past light-cone. There are around 10^23 stars in the
> universe. How many of these are within our own past light cone? How
> many are 3rd generation stars suitable metal rich? How many are not
> binary or triple star systems (the norm)? How many reside within the
> edges of the outer arm band of a spiral galaxy sweet spot, where gamma
> ray emissions are rare but metals are not? How stars exhibit suitable
> Sol-like radiance regularity? How many have an earth-sized rock
> within the star's habitable ring? How many of these planets have a
> tilted axis suitable for regular seasons? How many of these! have a
> single Moon? How many systems have asteroid sweeper Jupiter? How
> many of these planets exhibit friendly plate tectonics? How many have
> oceans large enough to moderate climate, but not too large so as to
> stifle evolution?
>
> This is not considering prerequisite atmospheric phenomena, any "life
> effects", or geological prerequisites to technological progress (on
> this planet we have had everything handed to us on a silver platter).
> How many metal rich stars are in our own past light cone? That is the
> starting point to whittle the number of earth simulation actors down
> to a low decimal figure.
Why does a species have to be Human-like in order to have space-age
technology?
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