Shostak notes that there are four primary suggestions as to why SETI hasn’t found a signal:
1. “You’re counting on the aliens using communication technology (radio, light) that’s oh-so-last century. They will be far beyond this.”Reasons #1, #3 and & #4 are useless, but #2 is one I'm partial to. As I've written before, the apparent dearth of ETI's in our galaxy is a disturbing observation.
2. “If hi-tech societies or thinking machines were out there, they’d have colonized the Galaxy by now. Clearly, we’re alone… lone… lone.”
3. “The aliens don’t want to communicate with us. Look at what we’re doing to the planet!”
4. “You SETI types are just looking in the wrong places. We know where the extraterrestrials are: on a planet in the Zeta Reticuli system.”
In response to suggestion #2, Shostak writes:
This is, of course, an appeal to the Fermi Paradox, which assumes that if sophisticated societies are common, they should also be ubiquitous. Well, I just checked the parking lot outside the Institute, and I see no large animals with long, prehensile noses. The conclusion a la Fermi is that elephants don’t exist on this Earth, right? After all, any putative pachyderms have had plenty of time to get to my office, even if only a few of them are so inclined. To use the Fermi Paradox as a reason for the lack of a SETI signal is to make a very big extrapolation from a very local observation. Seems chancy to me.This is a surprisingly weak answer from Shostak who has clearly misinterpreted the FP. No one is arguing that elephants should be ubiquitous. If we thought, for whatever reason, that elephants should occupy specific ecospaces on Earth, but they don't, then that would be a sort of observational conundrum much like the FP. I don't expect this, so I don't see this as a problem.
On the other hand, our expectations of AETI migratory behaviour and their potential megascale engineering projects are a horse of a different colour. The FP is about the absence of evidence when there should be evidence. And Shostak knows this; otherwise he wouldn't be pointing his radio arrays at the sky. It would be a convenience of the highest order if the first signs of ETI life were to be discovered now.
Shostak and others are guilty of grossly underestimating the characteristics of post-Singularity AETI's. Those, like Shostak, who dismiss the FP betray a misunderstanding of the potentials of artificial superintelligence, radically advanced computing and such technological artifacts as Von Neumann and Bracewell probes. And as usual, these dismissals fail to take into account the extreme age of the universe and the huge expanse of time that has preceded our own.
That said, Shostak may be (inadvertently) right about ETI localization. As argued by Cirkovic and Bradbury, AETI's may migrate from a biological habitable zone to a technological habitable zone -- one more conducive to megascale information processing projects like matrioshka and Jupiter Brains.
But Shostak and SETI, I'm sure, aren't considering these types of scenarios. My advice to SETI: keep on listening, but don't expect to hear anything.
Tags: SETI, fermi paradox, drake equation, astrobiology, astrosociobiology, cosmology, life on other planets, singularity.