X-Message-Number: 5537
Date: Wed, 3 Jan 1996 22:04:36 -0800 (PST)
From: Doug Skrecky <>
Subject: Re: nightmares

 In message #5519  wrote: 
 >You want nightmares? I'll give you nightmares. 
 >A couple of people recently on Cryonet (Clark & Metzger?) have
 >speculated on possible dark futures, one being related to the
 >apparent absence of superhuman extraterrestrials. 
 >I have commented on this many years ago, as has Mike Hart in a
 >couple of his books. it is exceedingly difficult to account for
 >the absence of such superhuman interveners in any way consistent
 >with BOTH optimism about our future and the notion that intelligent
 >and technologically advanced races have preceded us. Unless we are
 >the first, it seems hard to avoid pessimistic conclusions about the
 >fate of technologically advanced peoples. 
     Frank Tipler has advanced the view that we are alone because we are
 the first technologically advanced civilization to arise in our galaxy. 
 ETI's never killed themselves off because thery never existed. The
 December issue of Equinox magasine contains an article entitled "Earth: 
 There's No Life Like It" written by Terrence Dickinson, which outlines a
 number of reasons why the survival of life on earth can be regarded as an
 extremely low probability fluke. 
     One fact that I had not heard of before is that in computer
 simulations in which the earth & moon are removed destabilises the orbits
 of the other inner planets. Since a stable orbit is needed to restrict
 surface temperatures between the freezing and boiling points of water the
 stable orbits of the inner planets might be regarded as being a very low
 probability situation, equivalent to flipping a coin and having it come
 up on its edge. This argument has not yet been fully developed and
 further computer simulations will be needed before the low probabilities
 of stable orbits can be confirmed. 
     There exist a number of other apparently rare conditions upon which
 the development of intelligent life over billions of years is dependant
 on. These include the requirement of a Jupiter sized planet in the outer
 solar system to act as a shield against comets. Without Jupiter I have
 heard estimates of the time interval between comet hits on earth similar
 to the one which occurred 65 million years ago and wiped out the
 dinosaurs (and to comet Shoemaker-Levy 9 which just hit Jupiter!), of
 about every thousand years or so. No Jupiter = no intelligent life on
 earth. Astronomers have the capability to detect Jupiter type planets and
 have failed to find any. Jupiter seems to be a cosmic fluke. 
     The massive collision between a mars sized body and the proto-earth
 which just happened to form a large moon in a close orbit around the
 earth has also been regarded as a very low probability event. Without a
 large moon to stabilize the orbit of the earth, the green planet would be
 an ice planet. No moon = no intelligent life on earth. 
     If the earth were slightly more massive it would be like its sister
 planet Venus, which is a hellish inferno with surface temperatures above
 the melting point of lead. If an earth of mass were just 1% closer to the
 sun it would also be a hellish inferno. If the earth were slightly
 farther away from the sun it would have developed into an ice planet. 
 Earth is just the right size and is in just the right place. Another
 cosmic coin flip landing on its edge. 
     Finally after billions of years of placid existence the sun is alas
 soon to leave the main sequence and begin its slow increase in size to
 become a red giant. Original estimates of how much time life has left on
 earth ran to just 100 million years - that's all. However more careful
 consideration has upped this figuare somewhat. When one considers that
 evolution was basically at a standstill till just 600 million years ago
 (the Cambrian explosion) we might conclude that we just barely made it! 
     Coin flips landing on their edge: 
     1. stable orbits of inner planets
     2. Jupiter in outer solar system
     3. earth has very large moon
     4. just the right mass at just the right distance from the sun
     5. Cambrian explosion started just in the nick of time. 

     Rational conclusion: We are very, very lucky to be here. Our's is
 probably the first and only technologically advanced civilization to
 exist in our galaxy. 


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