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    Cancer got a reaction from Ragitsu in   
    A point I make in my classes about this: we do not yet know the resolution to the Fermi Paradox.
    In that I like to draw attention to another astronomical paradox, one framed multiple times since at least the Greeks, but most recently early in the 19th Century, Olbers' Paradox.  If you assume that the Universe obeys standard Euclidean geometry, and that it is infinite in spatial extent, and it is eternal (it has existed for infinite time, and presumably will continue to do so for infinite time, though that last is not required in the paradox), and uniform in content when averaged over an adequately large volume ... then one has to conclude that all sightlines in the Universe must eventually intersect the surface of a star, which means, the whole sky should be about as bright at the Sun's disk.  Obviously that is not observed.
    In the context of comparing this to the Fermi Paradox, I point out that all but one of the assumptions that went into Olbers' Paradox are incorrect (and perhaps a second is correct, but we can't evaluate that one).  The Universe is not eternal: it has a finite age.  It does not obey Euclidean geometry, though the degree to which it fails to do so does not seem to be important in the resolution of this paradox.  It may or may not be infinite in spatial extent, but we can't evaluate that because of the finite speed of light and the finite age of the Universe.  The one that that we do observe to be true is the one about uniformity in content, once one makes allowance for the finite age of the Universe and the evolution of the matter in it over time.  And, capping all that off, at the time of the framing of the paradox, absolutely none of those failures in assumption was known at the time (you could imagine all of those failures as possible resolutions to the paradox, but utterly no evidence was available to support belief in one as the resolution), and would not be known for more than half a century.
    So ... what is the resolution to the Fermi Paradox?  It is way too common to pick one assumption as being the obvious incorrect one, and wave away the problem.  As an instructor, I give that sort of thinking a grade of B-minus.  What if all the assumptions made in the Fermi Paradox are incorrect?  Or more than one, and not all?  Each failure and combination of failures has other implications for our views about life in the Universe, and it is worth considering those implications for each individual possible failure and combinations of them, because all of them lead to profound conclusions in their own right.
    So ... When I am asked about life elsewhere in the Universe, I avoid the "whole Universe" question.  I have no opinion informed enough to pass along.
    But when I started teaching, which was in a course on the Solar System, I did adopt an answer to the question about life on Mars (and this is any life, not intelligent, technological life, which the Fermi Paradox is concerned with).  And my answer is: I think that once we have the requisite ability on site to find it, then we will find that there is life on Mars, somewhere. 
    However, I am not willing to bet more than a beer on the issue.
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    Cancer got a reaction from Ragitsu in This happens to be my astrological sign. Apparently, it is yours as well?   
    It is, under classical Western astrology.  My username was a triple pun at the time I selected it.  The horoscope; my thesis project was on M67, a famous star cluster in Cancer; and at the time, I was employed as  a scientific programmer at Fred Hutchinson Cancer Research Center, developing a population microsimulation code for evaluating cancer screening strategies.
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