Fermi Paradox Explorer

Drake equation — how many communicating civilizations exist in the Milky Way?

R* — Star formation rate7 /yr
New stars forming per year in the Milky Way
fp — Fraction with planets0.50
Fraction of stars with planetary systems (Kepler: ~1.0)
ne — Habitable planets/star0.20
Average habitable-zone planets per star with planets
fl — Fraction with life0.13
Fraction of habitable planets where life emerges
fi — Fraction with intelligence0.01
Fraction of life-bearing planets developing intelligence
fc — Fraction communicating0.01
Fraction that develop detectable signals
L — Civilization lifetime10000 yr
Years a communicating civilization survives
Estimated active civilizations
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in the Milky Way right now
N = R* · fp · ne · fl · fi · fc · L
Galaxy visualization (each dot ≈ a civilization)
About: Frank Drake (1961) proposed this equation at the first SETI conference. Each slider is on a log scale. With optimistic values, N ~ millions; with pessimistic (Great Filter) values, N ~ 0. The Fermi Paradox: if N is large, where is everybody? Solutions range from the Great Filter (extinction bottleneck), rare Earth hypothesis, zoo hypothesis, to light-speed limits. Modern astronomy has sharpened R*, fp, and ne dramatically (Kepler mission: ~50% of Sun-like stars have Earth-sized planets), but fl, fi, fc, L remain deeply uncertain — spanning many orders of magnitude.