NAME
SETI::Drake - Estimate the number of interstellar communicating civilizations
SYNOPSIS
use SETI::Drake;
$d = SETI::Drake->new(
R => $stars,
fp => $planets,
ne => $support,
fl => $life,
fi => $intelligence,
fc => $communication,
L => $lifespan,
);
$n = $d->N;
printf 'You are ' .
($n > $threshold ? 'opt' : 'pess') .
"imistic: %0.2f\n", $n;DESCRIPTION
A SETI::Drake object answers the question, "How many interstellar communicating civilizations might be out there?"
METHODS
new
my $d = SETI::Drake->new($arguments);Return a new SETI::Drake instance. If no equation variables are provided, Drake's choices are used.
According to NOVA, Drake's values were:
R => 5, # Number of stars formed per year.
fp => 0.5, # Fraction of those stars that form planets.
ne => 2, # Average number of those planets that can support life.
fl => 1, # Fraction of those planets that actually do develop life.
fi => 0.2, # Fraction of those planets that then evolve intelligence.
fc => 1, # Fraction of those planets that develop interstellar
# communication.
L => 10000, # Average lifetime (in years) of an interstellar
# communicating civilization.According to Wikipedia, Drake's values were:
R => 10, # Annual rate of star creation in our galaxy.
fp => 0.5, # Fraction of those stars which have planets.
ne => 2, # Average number of planets which can potentially
# support life per star that has planets.
fl => 1, # Fraction of the above which actually go on to
# develop life.
fi => 0.1, # Fraction of the above which actually go on to
# develop intelligent life.
fc => 0.1, # Fraction of the above which are willing and
# able to communicate.
L => 10, # Expected lifetime (in years) of such a
# civilisation.Bradley Keyes of activemind.com computes it this way:
R => 1_000_000_000, # Number of stars in the Milky Way.
fp => 0.00001, # Fraction of stars that have planets
# (.0001% or 1 of 1,000,000).
ne => 0.33, # Number of planets per star capable of ecologically
# sustaining life.
fl => 0.00001, # Fraction of planets in ne where life evolves
# (.0001% or 1 of 1,000,000).
fi => 0.00001, # Fraction of fl where intelligent life evolves
# (.0001% or 1 of 1,000,000).
fc => 0.00001, # Fraction of fi that communicate
# (.0001% or 1 of 1,000,000).
L => 0.000000001, # Fraction of the planet's life during which the
# communicating civilizations survive
# 1 / 1,000,000,000th (10 years)N
$N = $d->N;Return the real number value of the Drake equation.
TO DO
Add meta-galactic terms to the equation?
SEE ALSO
http://www.pbs.org/wgbh/nova/origins/drake.html
http://en.wikipedia.org/wiki/Drake_equation
http://www.jb.man.ac.uk/research/seti/drake.html
COPYRIGHT
Copyright 2004, Gene Boggs, All Rights Reserved
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
See http://www.perl.com/perl/misc/Artistic.html
AUTHOR
Gene Boggs <gene@cpan.org>