/ 
SETI-Drake-0.02
River stage zero No dependents
/ SETI::Drake

NAME

SETI::Drake - Estimate the number of interstellar communicating civilizations

SYNOPSIS

use SETI::Drake;
my $threshold = shift || 10_000;
my $x = SETI::Drake->new(
    R  => $stars,
    fp => $planets,
    ne => $support,
    fl => $life,
    fi => $intelligence,
    fc => $communication,
    L  => $lifespan,
);
printf "You are %simistic: %0.2f\n",
  ($x > $threshold ? 'opt' : 'pess'), $x->N;

DESCRIPTION

A SETI::Drake object answers the question, "How many detectible, intelligent, interstellar communicating civilizations might be out there, in the galaxy?" by providing a single method, N(), which is a prediction based on the product of seven factors. In other words, this module does nothing more than multiply seven numbers together.

According to the Nova Origins video, "Where Are The Aliens?", Drake's values are:

R  => 10      # How many stars are formed each year, in the Milky Way?
fp => 0.5     # How many stars have planets?
ne => 2       # How many planets can support life?
fl => 1       # How many planets have life?
fi => 0.1     # How often will life becme intelligent?
fc => 1       # How many of those planets develop interstellar communication?
L  => 10,000  # How long might a technologically advanced civilaztion last?

We get an optomistic N = 10,000. According to the NOVA website however, Drake's values are:

R  => 5       # Rate of star formation per year, in the Milky Way
fp => 0.5     # Percentage of stars that form planets
ne => 2       # Average number of planets that could support life
fl => 1       # Percentage of those planets where life actually occurs
fi => 0.2     # Percentage of those planets where intelligence develops
fc => 1       # Percentage of intelligent species that procude interstellar communications
L  => 10,000  # Average lifetime (in years) of a communicating civilization

But again, we get N = 10,000. Whew. That was close.

Anyway, according to Wikipedia, Drake's values from 1961 were:

R  => 10    # Annual rate of star formation 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 => 0.01  # Fraction of the above which actually go on to develop intelligent life.
fc => 0.01  # Fraction of the above which are willing and able to communicate.
L  => 10    # Expected lifetime (in years) of such a civilisation.

Giving a slightly pessimistic value of 0.01 for N.

METHODS

new()

my $d = SETI::Drake->new( %arguments );

Return a new SETI::Drake instance. If no equation variables are provided, Frank Drake's choices (from his 2004 chalkboard video interview on Nova) are used.

N()

$N = $d->N();

Return the real number value of the Drake equation:

N = R* x fp x ne x fl x fc x L

SEE ALSO

http://en.wikipedia.org/wiki/Drake_equation

http://www.pbs.org/wgbh/nova/origins/drake.html

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>