Crosswords2 mins ago
aliens
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For more on marking an answer as the "Best Answer", please visit our FAQ.Drakes Equation
N = fs * fp * ne * fld * fi * fc * fl
where,
N = The number of communicative civilizations in the Milky Way
fs = The number of stars in the Milky Way
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
fld = 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)
fl = The fraction of a planet's lifetime that has a technological civilization
If we substitute,
N = fs * fp * ne * fld * fi * fc * fl
N = 400 billion (1/4) 2 (1/2) (1/10) (1/10) (1/100 million)
N ~ 10 technological civilizations in just the Milky Way Galaxy!
What would we do to determine the number of technological civilizations that exists in the Universe? Multiply this by billions; the number of galaxies in the Universe!. Remember this is just for technological civilizations !