I doubt they'll be listening in on FRIAM, Tom. :-/
--Doug On Sat, Mar 31, 2012 at 2:50 PM, Tom Carter <[email protected]> wrote: > > [snip] > > Hence, if we want to look for "advanced civilizations," it seems we > should be looking for relatively quiet "white noise" sources . . . :-) > > tom > > > > On Mar 31, 2012, at 12:02 PM, Douglas Roberts wrote: > > > A couple of comments: > > > > 1. Recent research shows that there are tens of billions of rocky > planets inhabiting the habitable liquid water zone in our galaxy alone. See > > > > > http://www.physorg.com/news/2012-03-billions-rocky-planets-habitable-zones.html > > > > 2. Multicellular life started on earth about 540 million years ago > > > > 3. 250 million years ago the Mesozoic era began -- trees, dinosaurs > > > > 4. Homo Sap. has been around for maybe 100,000 years, or about > 0.000000007% of the total time since the big bang. > > > > 5. There are perhaps 200 billion galaxies in the observable universe, > and nobody even knows if the diameter of the universe is 78 billion light > years in diameter, or infinite. > > > > Given the above, I'd say the chances there this is life out there are > considerably greater than the chances of winning the mega-millions lottery. > Whether any of that life evolves to the point of developing what we might > call intelligence before catastrophe intervenes is an interesting question. > There have been 5 mass extinctions on earth: > > > > • The first great mass extinction event took place at the end of > the Ordovician, when according to the fossil record, 60% of all genera of > both terrestrial and marine life worldwide were exterminated. > > • 360 million years ago in the Late Devonian period, the > environment that had clearly nurtured reefs for at least 13 million years > turned hostile and the world plunged into the second mass extinction event. > > • The fossil record of the end Permian mass extinction reveals a > staggering loss of life: perhaps 80–95% of all marine species went extinct. > Reefs didn't reappear for about 10 million years, the greatest hiatus in > reef building in all of Earth history. > > • The end Triassic mass extinction is estimated to have claimed > about half of all marine invertebrates. Around 80% of all land quadrupeds > also went extinct. > > • The end Cretaceous mass extinction 65 million years ago is > famously associated with the demise of the dinosaurs. Virtually no large > land animals survived. Plants were also greatly affected while tropical > marine life was decimated. Global temperature was 6 to 14°C warmer than > present with sea levels over 300 metres higher than current levels. At this > time, the oceans flooded up to 40% of the continents. > > > > Were it not for that last one, intelligent life on earth might be > sauron-based, rather than (arguably) hominid-based. However, having > observed that the demonstrated proven benefits of intelligence on earth > include religion, religious war, a fascination with building enough nuclear > weapons to guarantee another mass extinction event, and a propensity for > breeding beyond the capacity of the planet to supply food and water for a > rapidly growing population of billions, I'd say that the odds were pretty > good that we won't be around to meet another intelligence, should one ever > happen to come looking this way. > > > > However, if you are a Sarah Palin or Rick Santorum or Rick Perry-class > creationist, please ignore all of the above. Humans and dinosaurs were > happily co-existing from the beginning, 6,000 years ago, and God made us in > his image, and we are the chosen. Which makes the whole question of other > intelligence completely immaterial. > > > > If you are a Mitt Romney-class Mormon, you may pass directly on to > Kolub; the issue of intelligent life is obviously of no meaning to you. > > > > --Doug > > > > On Sat, Mar 31, 2012 at 11:09 AM, Owen Densmore <[email protected]> > wrote: > > > > > > I got to thinking a bit more about an assumption I (and I bet most of > us) have held, that surely there is "intelligent" life on other planets, > one capable of technology .. thus SETI's radio search. Surely it is hubris > to claim humanity is somehow unique, just look at the diversity of our own > world! Thus there's got to be lots of intelligent life out there, right? > > > > > > (Yes, I know, this is pretty vague, and we're intelligent only for > very small values of intelligent.) > > > > > > But listening to a TED by Hawking, I was impressed with his somewhat > measured approach: that we have not found a radio source within 200-400 > light years. I believe his choice of distance had to do with our own > development of radio a couple of centuries ago. > > > > > > That got me reading up on just how long we've been around, and how > long other civilizations could have existed. Very roughly speaking, the > big bang was 14 billion years ago, our sun is 4.5 billion years old, and > the earth is 4 billion years old. > > > > > > Well, that sounds like we're late to the game: 4 billion years old in > a universe 14 billion years old. But wait a minute, we know we're the > result of star-stuff, the heavy elements. The big bang was only able to > muster nuclei of fairly low weight, lithium say .. possibly a bit more. > The first generation of stars, therefor were fairly odd, huge and short > lived. And the second generation of stars were less heavy element rich > than our sun, which makes it at best third generation. http://goo.gl/gV54S > > > > > > So given only 14BY for building solar systems, and assuming the > requirement for an at least third generation sun, we may be as young as > likely a life form possible. > > > > > > So SETI is likely playing a loosing game, we're young enough that the > statistics may be that, yes there is life out there, but it's pretty young > too and maybe is no more advanced than we are. (Maybe that is Hawking's > couple of centuries limit) Of course we're talking about a few centuries, > which would make a huge difference in technology, but still. > > > > > > Hawking does end with a grim comment others have made: maybe > civilizations are short lived .. they self destruct or fall prey to > destructive events (meteors, comets). > > > > > > -- Owen > > > > > > ============================================================ > >
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