What is the Drake Equation?
by Steve Ford, WB8IMY
Is there a way to estimate the number of technologically advanced
civilizations that might exist in our Galaxy? While working at the
National Radio Astronomy Observatory in Green Bank, West Virginia,
Dr. Frank Drake conceived a means to mathematically estimate the
number of worlds that might harbor beings with technology
sufficient to communicate across the vast gulfs of interstellar
space. The Drake Equation, as it came to be known, was formulated
in 1961 and is generally accepted by the scientific
community.
N = R* fp ne fl fi fc L
where,
N = The number of communicative civilizations
R* = The rate of formation of suitable stars (stars such as our
Sun)
fp = The fraction of those stars with planets. (Current evidence
indicates that planetary systems may be common for stars like the
Sun.)
ne = The number of Earth-like worlds per planetary system
fl = The fraction of those Earth-like planets where life actually
develops
fi = The fraction of life sites where intelligence develops
fc = The fraction of communicative planets (those on which
electromagnetic communications technology develops)
L = The "lifetime" of communicating civilizations
Frank Drake's own current solution to the Drake Equation estimates
10,000 communicative civilizations in the Milky Way. Dr. Drake, who
serves on the SETI League's advisory board, has personally endorsed
SETI's planned all-sky survey.
