Eric, Your comments below are such a mix of lucidity and obfuscation that I am not sure I can disentangle the two. Here's my attempt with previous apologies:
Eric Hawthorne wrote: > On the likelihood of detecting alien intelligences: > (single-world case) > > 1. It is an enormously stupid conceit of us to assume that > aliens would be broadcasting, or tightbeaming something like > analog radio signals, for communication. > We ourselves have only being doing that for 100 years, > and will be ceasing to do it before the next 100 are up, > having switched to a combination of closed fibre-optic and > massively spread-spectrum (i.e. noise-like) digital radio. There is a group of people in the institution I work for who spend their time and some taxpayer's money doing just that. I would not call them stupid but this is what I can anticipate of their answer: they do not look at radio signals and they only did that because that was the only spectrum accessible for a long while. Today the radio universe is pretty well charted so they are looking at MW,Visible, UV,Xray data etc... as satellite missions make each part of the spectrum available. The correlation techniques developed beforehand are now sharp enough to use with broad spectrum data... > 2. We have not built dyson spheres, nor are we likely > to. There were a number of crazy megaproject engineering > fantasies that we had for the first few short years after > we discovered how to build with reinforced concrete, and > Dyson spheres were one of them. (As were those incredibly > ugly but functional 60s and 70s concrete skyscrapers. The > first crude phalluses erected using a new but not completely > mastered building technique. > > I'd like to think that we have a slightly more refined > sense of megaproject risk analysis now that will prevent > us doing quixotic projects like Dyson spheres. How are analog radio waves somehow "passe'" in your opinion but Dyson sphere and Rings or skyscrapers any kind of standard for observing alien life? Or our own, by that matter? > > 3. We can barely detect planets the the size of Jupiter around > nearby stars today. Why would we be able to detect non-radiating > dyson spheres? Wouldn't we mistake them for black holes at the > least? Try to see it this way: in a mere 4 years and employing a single technique (maybe a couple) we have been able to detect a good 150 Jupiters (give or take)! I'd say it is not a bad working rate specially for a race that had not found one for a few million years. Now when you consider that, for two or three jupiters we may anticipate a dozen or so habitable zones in our close experience I'd say you would not have to be a Sagan to find this encouraging... > > 4. The life span of a higher mammal species (clad, actually i.e. > tree of derived species i.e. branch of evolution) > like ours is estimated in biology to be 5 to 10 million years, > and we're a significant way through our tenure, so we'd > better hurry up sending out those self-replicating V-ger > robot probes all over the place for them to be detected a > million years hence. We'll probably be gone (as a species > and clad) by the time the reply arrives. I'd say that by your count we are already gone! In any case nothing you say above appears relevant to the gist of Fermi's argument which is taken perhaps too seriously by many of ET's friends! The best answer I have heard is in the way of your first point above: how arrogant of us, backward eartlings, to assume that any advance civilizations would care to meet us! Cordially, -Joao Leao -- Joao Pedro Leao ::: [EMAIL PROTECTED] Harvard-Smithsonian Center for Astrophysics 1815 Massachussetts Av. , Cambridge MA 02140 Work Phone: (617)-496-7990 extension 124 VoIP Phone: (617)=384-6679 Cell-Phone: (617)-817-1800 ---------------------------------------------- "All generalizations are abusive (specially this one!)" -------------------------------------------------------
