GLG 311_Lecture_Drake_Equation

GLG 311_Lecture_Drake_Equation - ! Astrobiology Roadmap....

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Unformatted text preview: ! Astrobiology Roadmap. GLG 311: Essentials of Astrobiology Today: Wednesday: ! Drake Equation (Textbook: Side bar 10.2, Pages 246-247; see also Astrobiology Primer, Section 3C) Next Monday: ! What is life? Class exercise with discussion. (Textbook, Chap.1; Cleland and Chyba 2002) Birth of Radio Astronomy and the Search for Extraterrestrial Intelligence (SETI) ! Radio astronomy involves the study of radio waves emitted from natural sources. The Feld blossomed after the development of radar during WWII and was well established by 1950 (see Sullivan and Carney, 2007 for history). ! ¡irst major US ¡acility (NRAQ, the National Radio Astronomy Observatory in Green Bank, West Virginia) established in the mid-1950s (now includes nearby facilities in Socorro NM and Tucson, plus others). ! In the late 1950s, radio astronomy made interesting discoveries of radio sources for which there was no optical counterpart; also mapping of Milky Way based on hydrogen emissions. SETI developed out of an early marriage between radio astronomy and interest in the question of intelligent life elsewhere in the universe. ! ~1959 ¡rank Drake began his graduate career at Cornell with the idea of using the NRAO to search for signals from other civilizations in the nearby galaxy (within ~10 light years of Earth. That same year (1959), Coconni and Morrison published a thought paper supporting the radio searches for intelligent life by looking in the microwave 21 cm (= emission for neutral hydrogen); At the same time, Drake kicked off his Project “Ozma” (from Baum’s Land of Oz), using 1,420 Ghz (between emissions for H and OH radicals), focused on the stars, Tau-Ceti and Epsilon Eridani National Radio Astronomy Observatory, Very Large Array, Socorro NM Enrico Fermi Frank Drake Today’s lecture will focus on the ideas of two scientists: On the Side of Pessimism: The Fermi Paradox ! Enrico Fermi (1901-54): His calculations showed that with only modest rocket technology, traveling at a small fraction of the speed of light, a civilization could completely colonize the galaxy within a short time (few tens of millions of years). ! His calculations were based on the logistical growth equation, which describes population growth (exponential; see next slide). ! The Paradox: If there are many civilizations out there, where are they? ! Here another concept come into play: The “Anthropic Principle” states that the only universe we can see is one that supports life. If it were a different type of universe, we would not exist to see it....
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This note was uploaded on 03/01/2011 for the course SES 311 taught by Professor Farmer,j during the Spring '08 term at ASU.

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GLG 311_Lecture_Drake_Equation - ! Astrobiology Roadmap....

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