AST 309L Search for Life in the UniverseInstructor: John ScaloTeaching Assistant: Ross FalconClass Website: http://www.as.utexas.edu/astronomy/education/fall08/scalo/309l.htmlDownload course syllabus in Word format (linkable)Notice calendar chapters to be read (not same order as book)and exam datesOutline of most class lectures will be available for download as pdfversions of ppts--these are only outlines!Handouts, suggested end-of-chapter questions, review sheets for exams,etc. will be located here.Contains link to eGradebook for checking exam scores, and to textbook“Student Companion Website.”Will contain external links for “homework assignments”Textbook: Life in the Universe (2nd edition)by J.O. Bennett & S. ShostakCo-op: Price unknown ??New: Amazon $98, Barnes & Noble $109Used: As low as $78 + shipping + timeDon’t buy 1st edition!Student!!Companion Website:http://wps.aw.com/aw_bennett_liu_2There is no study guide, cdrom, or other “extras”.Most of the extras you need are at :Inside you will find tutorials, movies, interactive figures,links, glossary,flashcards, calculator and periodic table (the last two are unnecessary).“Links” is particularly valuable.Assignment: By Tuesday Sept. 2, skim entire textbookin order given on the Reading Assignments list, notreally reading, just noting topics, illustrations. If youhave a good overview of the material we are coveringand why, you will do better in the course.Features of textbook websiteLinks: Well-organized, up-to-date, and easy to navigate.Flash cards: Could be surprisingly useful. Use for chapters as we coverthem, to become as comfortable as possible with terminology.Tutorials: Only four of them, but appear to be very useful.Two assignments (do them by Tuesday) within textbook website:A. Read in Links: A Universe of Life, Link to simple math review inChemistry Basics Reminder (sends you to Chem Tutor web site),Numbers and Math, only Measured Numbers…, ScientificNotation, Significance and Rounding, then Proportionality. I willcover “Units…” in class; ignore material you find here.B. Read in Links: A Universe of Life, the material on Light Years. Whichunit does your textbook use, light years or parsecs? Use opportunity toreview any other astronomy topics that are relevant (see list there).Math and numbersYou will be asked to manipulate the simplest of formulas, and very rarely.I will give examples in class and in handouts. There are also only a fewnumbers that you will have to memorize, and I will tell you what they are.An example: You will be expected, by the end a particular section of thecourse, to be able to name the events in the history of the Earth, that arebelieved to have taken place at the times marked with the arrows: However, you will be expected to understand the concepts, ideas, andreasoning behind all the material, and should be able to articulate them.Some math you should practiceScientific notation: you don’t have to use it, just be ableto read it.Simplest of logarithms, base 10. So we can make graphsof things that vary by many orders of magnitude.Simply related to scientific notation aboveGraphs: If you are uncomfortable with graphs, do somereview immediately. Make one yourself! Find some inour textbook.Wander through these for familiarityClass websitehttp://www.as.utexas.edu/astronomy/education/fall08/scalo/309l.htmlTextbook websitehttp://www.as.utexas.edu/astronomy/education/fall08/scalo/309l.htmlFor homework and in case you want alternative presentation of somematerialwww.astrobionet.comWhat are we looking for?Where should we look?AST 309LThe Drake Equation as organizingtool, and its implications(9/2/08)Galaxies like ours: How many of these 100 billion stars might have planets,with life, or with “intelligent” life? We can organize the issues we have toaddress with the “Drake equation.” (Sec. 12.1) NGC 4414 M 100Q: Why shouldn’t we search for life in these galaxies?How do we search? What is required to have life? Complex life?Life we could communicate with?The “Drake Equation” simply organizes these supposed requirements into separatefactors, sort of a list of possibilities for our consideration star--about 1011 in our galaxy. Average separation is a few light years. (Compare with size ofGalaxy: about 100,000 light years) planet--indirect arguments from theory as well as direct observations of extrasolar planets suggestgiant planets may be very common. But Earth-like (much smaller, rocky) planets? The Drake equationquestion: What is the probability that a star has a planet? habitable planet--requires a liquid? Liquid water? Nearly everyone agrees this is fundamental(we’ll discuss why later). Requires special temperature range, and so only certain range of distancesfrom star.Probably additional factors for habitability, like planetary mass (for atmosphere, geology,…)Drake question: What are chances that a planet will be habitable? life--How probable or improbable? Need to understand how life arose and developed on Earth (ouronly example). We will spend the 2nd part of this course discussing the many theories, experiments,and types of evidence related to this. What are chances life will develop on a habitable planet? intelligence--What does this mean? Are there different “types”? Why think that extraterrestrialswould share our forms of cognition? Compare cross-cultural, cross-species, cross-historicalcognition.What is probability that life elsewhere develops “intelligence? communication—representation, language. How likely? Other forms? length of time spent communicating—we expect any nearby civilizations to have had a longlifetime. (We’ll see why this is so shortly.)Now we just assign a symbol for each one of these, representing its probability ofoccurrence, and multiply all of them together. See pp. 400-401Another way to see the main idea in terms of convergence and contingencyWhat is the likelihood or probability thatthe sequence of events shown to the rightwill occur, ending up with the peculiargroup of phenomena listed at the bottombranching? And are there many otherpossible branchings that we haven’tthought of, or are incapable (for, say,biological reasons) of imagining?Convergence is related to determinism,inevitability. If it occurred in one place,it was probably useful, and will ariseelsewhereContingency is related to randomness,uncertainty, sensitivity to slight changesin
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