Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site mmintl.UUCP Path: utzoo!linus!philabs!pwa-b!mmintl!franka From: franka@mmintl.UUCP (Frank Adams) Newsgroups: net.sf-lovers Subject: Re: The Great Silence Message-ID: <579@mmintl.UUCP> Date: Fri, 9-Aug-85 14:20:51 EDT Article-I.D.: mmintl.579 Posted: Fri Aug 9 14:20:51 1985 Date-Received: Mon, 12-Aug-85 06:28:04 EDT References: <3157@topaz.RUTGERS.EDU> Reply-To: franka@mmintl.UUCP (Frank Adams) Organization: Multimate International, E. Hartford, CT Lines: 44 Summary: They're everywhere! They're everywhere! In article <3157@topaz.RUTGERS.EDU> bnw@crash.UUCP writes: >From:> >Perhaps the problem is simply that there is no reason why anyone should have >found us. This is an excerpt from _Cosmos_ by Dr. Carl Sagan. > ". . .If a great many years ago an advanced interstellar spacefaring >civilization emerged 200 light-years away, it would have no reason to think >there was anything special about the Earth unless it had been here already. >No artifact of human technology, not even our radio transmissions, has had >time, even travelling at the speed of light, to go 200 light-years. From >their point of view, all nearby star systems are more or less equally >attractive for exploration or colonization." > ". . .A sphere two hundred light-years in radius contains 200,000 suns >and perhaps a comparable number of worlds suitable for colonization. . ." > > Why the silence? We're just one little regarded blue-green world at >the unfashionable end of a spiral arm in the Milky Way galaxy. One more time ... an intelligent race with interstellar flight doesn't go to just a few places, it goes everywhere. All nearby star systems are more or less equally attractive, so you colonize all the nearby star systems. A few dozen generations later, you have filled up all the nearby star systems, so you colonize the next layer out. In a few hundred thousand years, you have filled the galaxy. All of it. A race from a planet where life started at the same time as on Earth, which evolved to a technological civilization one percent faster, has had thirty million years or so to spread out since. That is time enough to fill the galaxy about a hundred times over. "They just haven't found us [yet]" is just not an adequate explanation. Most plausible explanations for why they aren't here are variations on three themes: (1) they aren't there, (2) they are deliberately leaving us alone, and (3) war prevents permanent settlement of planets. And remember the time scales involved for (2) -- they have to have decided to leave "us" alone while "we" were dinosaurs (or perhaps earlier; I'm not quite sure of the evolutionary time scale (if you don't believe in the evolution of species, send comments to net.origins where I won't have to read them)). Now this does not mean that SETI is hopeless. They may be just waiting for us to contact them to welcome us into the Galactic Federation. But it seems about equally likely to me that as soon as they detect us, they will come by to sterilize our planet, before we can do the same to them. But we should not *expect* SETI to succeed.