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
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
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