Drake Equation
N = R x fs x ne x
fl x fi x fc x L
R: average rate of star formation
fs: fraction of stars with planetary systems
ne: numbers of planets in "habitable" zones
fl: fraction of planets where life develops
fi: fraction of planets where life becomes intelligent
fc: fraction of intelligent civilizations which want to communicate
L: lifetime of "communicative life"
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People have long wondered whether we are unique or not. Frank Drake of Cornell
University formulated what is now known as the
Drake Equation in 1960 as
a way to open the discussion on the possibility of
intelligent life in the galaxy. At left is the Drake
Equation and the meaning of the terms in the
Drake Equation. We consider
each term in the Drake Equation and
come up with an answer as to the number of intelligent civilizations
likely to exist in the Milky Way galaxy.
The terms in blue
are probabilites
and facts which
can be deduced from astrophysics. These terms can, in principle, be
determined quantitatively. The sections in green
are probabilities and
numbers which come from biology, psychology, and sociology. These are
much more difficult to estimate. |
