a curmudgeonly view of seti

A curmudgeonly view of SETI

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)

N* = number of stars in the Galaxy

~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

fe = fraction of Earthlike planets

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

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• 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

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

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?

Deliberate/accidental detection

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

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

• Gravitational lensing• Lasers• Interstellar scintillation as a free amplifier• Chasing beamed phenomena• Local ambassadors

Star-star microlensing

Gamma-ray bursts as beacons

Gamma-ray bursts as beacons