A curmudgeonly view of SETI :A curmudgeonly view of SETI


Drake (Green Bank) equation :Drake (Green Bank) equation This (which can be written in many similar ways) at least organizes our ignorance. But is it leading us to concentrate on the right questions? In other words, who needs it? In any case, we can look at the terms: N=N* fp fe fl fi fc (L/Lmax)


Slide 3:N* = number of stars in the Galaxy


Slide 4:~400 billion (the McDonald’s number) N* = number of stars in the Galaxy


fp = fraction of stars with planets :fp = fraction of stars with planets


fp = fraction of stars with planets :fp = fraction of stars with planets


fe = fraction of Earthlike planets :fe = fraction of Earthlike planets


How earthlike is earthlike? :How earthlike is earthlike? We can see how to do global assays nearby Environment where life appeared??? Solar System environments may help “Rare Earth” or not? Mass, large moon, temperature range, tides, rotation period, lifetime, liquid water, atmosphere, location of Jovian neighbors – which matter???


fl = fraction of life-bearing planets :fl = fraction of life-bearing planets


fi = fraction of living worlds with intelligence :fi = fraction of living worlds with intelligence Fossil record: complexity, rather than appearance of first life forms, is the time bottleneck


fi = fraction of intelligences which develop communicative civilizations :fi = fraction of intelligences which develop communicative civilizations SETI involves either interstellar communication or starflight,defining the sample First per planet may always win… Contingency (Africa versus South America)


L =lifetime in communicative state :L =lifetime in communicative state


Beware of psychological mirroring :Beware of psychological mirroring Conventional widom at various times has thought of L ended by nuclear war, ecological collapse, “Chinese coup”, era of navel-gazing Communication imperatives? Primogeniture and European expansion: drivers for exploration “accidental”


Natural (dis)advantages :Natural (dis)advantages Jared Diamond, in Guns, Germs, and Steel, make a strong argument that geography and ecology picked the winners in human development long ago. What unseen advantages might we, or might hypothetical intelligences, have or lack?


What good is intelligence? :What good is intelligence?


Deliberate/accidental detection :Deliberate/accidental detection Our own leakage decreases – is “accidental” detection itself an accident of development?


How to cheat Frank Drake :How to cheat Frank Drake Interstellar expansion (and there are Earthly lessons – Vinland versus Florida) Multiple (dis)appearances of intelligence (a la Karl Schroder’s Permanence) Ignorance of “Earthlike” context Scouring of worlds by cosmic events


New(ish) Approaches :New(ish) Approaches Gravitational lensing Lasers Interstellar scintillation as a free amplifier Chasing beamed phenomena Local ambassadors


Slide 22:Star-star microlensing


Gamma-ray bursts as beacons :Gamma-ray bursts as beacons


Gamma-ray bursts as beacons :Gamma-ray bursts as beacons