How
Likely is Radio Contact With Extraterrestrial Intelligences?
NIC = RIC
x LIC = Rstar x Pplanets
x Phabitability x
Psimple life x Pcomplex life x Pradio signals x Lradio
era
RICxLIC rate at which civilizations
appear x their lifetime
Astronomy
Rstar rate at which stars are formed
in the Galaxy
Pplanets probability a star will have
planets
Phabitability
probability
a planet will be suitable for life
Biology
Psimple life probability bacteria will
arise on a suitable planet
Pcomplex life
probability
bacteria will evolve into complex life
Sociology
Pradio signals probability complex life will
send out radio signals
Lradio era total duration during which
radio is sent