108 lines
5.3 KiB
Plaintext
108 lines
5.3 KiB
Plaintext
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From the SETI notebook of James Brown
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Drakes Equation
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One of the first things asked when I say that I am evolved in the
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search for extraterrestrial life is "what makes you think there
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is any one else in the universe ?". That's a very good question
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and one that deserves an answer. It is also one that has not
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been successfully answered over the whole of human experience.
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Carl Sagan participated in a conference of people interested in
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the question of Communication with Extraterrestrial Intelligence
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(CETI) that was held in the USSR back in 1971. In his
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introduction address he said something that gets the whole thing
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in perspective. He said "..the cetaceans (whales) are
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undoubtedly another intelligent species inhabiting our planet,
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and it has been argued that if we cannot communicate with them we
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should not be able to communicate with extraterrestrial
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civilizations". Without much reflection it would seem that it
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should be much easier to communicate with whales than ET's.
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After all we share the same planet, both breath oxygen, eat
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plants that depend on the sun for there energy source. But since
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that meeting, 15 years ago, we are no closer to talking with
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whales than we ever were.
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The conference had as its agenda the task of estimating the
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possibility of communication with extraterrestrial intelligence
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and since they were all capable scientific people they felt it
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necessary to express there doubts and optimism in the form of
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mathematics. Dr. Frank Drake was at the same conference and had
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sometime earlier created a mathematical expression of the
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possibility that could be used as a framework for this and future
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discussions.
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Drakes equation became a way for experts to tackle the problem
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piecemeal, concentration in there own specialty without trying to
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understand the question as a whole. For example the evolution of
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technical civilizations was taken by an anthropologist, the rate
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of star formation in the universe by a cosmologist, etc.
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The equation is:
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N = R Fp Ne F1 Fi Fc L
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Where:
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N = Number of civilizations to look for
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R = Rate of star formation
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Fp= Fraction of stars with planetary systems
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Ne= Ecologically suitable planets.
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F1= Fraction of planets on which life occurs.
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Fi= Fraction of planets with life AND intelligent life
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Fc= Fraction with communication capabilities like ours
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L = Life time of such a civilization
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It was generally agreed on that the terms most easily estimated
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were the rate of star formation and the number of stars with
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planets. The most difficult term was "L" the life time of an
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intelligent civilization because we only have experience with one
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such civilization and it appears intent on terminating itself at
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the earliest possible moment.
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AS you would expect none of these things can be estimated with
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anymore than a good guess but here is what the results seem to be
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based on everything we now know about the problem. An optimist,
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like Dr Sagan would say that there is at least 300,000
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civilizations that are capable of sending signals and that we
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could detect in our galaxy alone. A pessimist, and there were
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several even in that conference, would say that there can be as
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few as 100 possible civilizations down to and including zero.
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So what is the true number of civilizations? We shall never know
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because even when we find the first, we shall never know when we
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have found the last.
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So what is the true number of civilizations?
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X-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-X
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Another file downloaded from: NIRVANAnet(tm)
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& the Temple of the Screaming Electron Jeff Hunter 510-935-5845
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Rat Head Ratsnatcher 510-524-3649
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Burn This Flag Zardoz 408-363-9766
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realitycheck Poindexter Fortran 415-567-7043
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Lies Unlimited Mick Freen 415-583-4102
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Specializing in conversations, obscure information, high explosives,
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