Evaluating the Odds Pessimistically
NIC = RIC
x LIC = Rstar x Pplanets
x Phabitability x
Psimple life x Pcomplex life x Pradio signals x Lradio
era
Pessimistic
Estimate
Rstar observed rate: 10 per year
Pplanets observed discoveries: 0.1 (no terrestrials known)
Phabitability
extreme
life: 0.01 (surface liquid
water)
Psimple life rapidity of Earth life 0.1 (we got lucky)
Pcomplex life
long
time on Earth 0.01 (looks
tough)
Pradio signals who knows? 0.001 (what good are radios?)
NIC = Lradio
era/100
million
duration doesn’t much
matter…
Pessimistic Conclusion:
There’s nobody home (except for
us!).
Let’s be careful, live long, and
prosper!
