In an April 4 paper in arXiv, Adrian Kent of the University of Cambridge and Perimeter Institute suggested two alternate reasons why we haven’t heard from extraterrestrials:
•“Intelligent species might reasonably worry about the possible dangers of self-advertisement and hence incline towards discretion” — the “Undetectability Conjecture,” suggested by Beatriz Gato-Rivera.
•Strengthening that argument: “Evolutionary selection, acting on a cosmic scale, tends to extinguish species which conspicuously advertise themselves and their habitats.”
Referring to this new article, the good folks at Kurzweilai.net added:
"In SHOUTING AT THE COSMOS … Or How SETI has Taken a Worrisome Turn Into Dangerous Territory, astrophysicist and science-fiction author Dr. David Brin advises that “people who care about [transmissions from Earth] — preferring a wide-ranging discussion before a few individuals start screaming into space on our behalf — are going to have to do some yelling of their own.” He explores this issue further in A CONTRARIAN PERSPECTIVE ON ALTRUISM: THE DANGERS OF FIRST CONTACT and other thought-provoking articles."
Thanks Kurzweil folks!
Alas, I have been wrassling with the Fermi Paradox since before it was called that! Back in 1985 I named this mystery "The Great Silence" in what is still the only full review article ever published on the subject.*
There I cataloged almost a hundred explanations that people have offered for the silence and the impression that we have - so far - of being alone in the cosmos. Alas, most folks tend to choose one particular answer, over all the others, for reasons having a lot more to do with individual psychology than either logic or evidence!
If you look at the good old Drake Equation (it needs to be expanded by a couple of factors), then it's clear that some factor must be lower-than-expected, in order to make the emptiness that we seem to see around us. But which factor?
Funny thing. Those who *want* the cosmos to be empty of competition (so we can fill it with our descendants) tend to choose factors on the left side of the Drake Equation - e.g. those having to do with the number of potential life-bearing worlds, or the likelihood of biogenesis, or of intelligence or industrial civilization.
Those who are eager for contact - like the SETI folks - tend to choose factors on the right side to blame for the apparent absence of neighbors. Factors that let them say "that just means things are a little sparse; but give us time. Those signals will show up any minute!"
The saddest thing that I've noticed? Once a person picks a favorite explanation, he or she tends to cling to it, vociferously sure that all other theories are utter nonsense. I've seen this happen to some of the smartest guys I know. Such certainty... in a realm that has been called "the only scientific field without any known subject matter."
Almost nobody seems willing to admit "We just don't know; there's too little data. A dozen of the best explanations may be true, maybe even several at once. So let's act accordingly."
As for the theory recently published? The so-called "Darwinian Explanation" amounts to "they're all cowards out there, because some predatory types may be mean. So everybody's hiding." Well, well. It is an old, old, old hypothesis. It's been around a boringly long time, though sadly it seems that the authors think they invented it.
Heck that explanation could be true. Indeed, because it might be true, I am part of a growing movement trying for a moratorium on idiotic "message-to-ET" shouting, at least till we learn a bit more and have had a chance to discuss these matters, openly, like adults. Still, that doesn't make the idea original.
(Or even especially likely. The notion of a universe filled with cowards... who stay cowardly FOREVER, no matter how advanced they become... seems no only unimaginative and temporally myopic, but deeply dismal, as well.)
Someday, I hope, some people will enter this field interested in exploring the full scope of ideas, the way grownup scientists do in almost any other field, actually reading the literature and comparing past arguments and progress before blabbing "I just figured it out!"
Perhaps it will happen one day, when curiosity and professionalism outweigh impulsive egotism. Heck, maybe then we'll be worthy and ready for contact.
--See more articles on SETI: Search for Extraterrestrial Intelligence
* My "Great Silence" paper about the mysterious Fermi Paradox, the strange lack of signs, in the heavens, of extraterrestrial intelligent life. Quarterly Journal of Royal Astronomical Society, fall1983, v.24, pp283-309 (Downloadable at my website
or at http://adsabs.harvard.edu/abs/1983QJRAS..24..283B )