DIRD_25-DIRD_An_Introduction_to_the_Statistical_Drake_Equation.pdf

UNCLASSIFIED / /*@R-OFFECHH-UGEONEE Defense Intelligence Reference Document Fo Acquisition Threat Support 11 March 2010 ICOD: 1 December 2009 An Introduction to the Statistical Drake Equation UNCLASSIFIED / APOR"OPEECEREUSE CONEY

UNCLASSIFIED / /POR OTFCC E sh ores An Introduction to the Statistical Drake Equation Prepared by: (b)(3):10 USC 424 Defense Intelligence Agency Author: (b)(6) Administrative Note COPYRIGHT WARNING: Further dissemination of the photographs in this publication is not authorized. This product is one in a series of advanced technology reports produced in FY 2009 under the Defense Intelligence Agency, }(b)(3):10 USC 424 Advanced Aerospace Weapon System Applications (AAWSA) Program. Comments or questions pertaining to this document should be addressed to |(b)(3):10 USC 424;(6)(6) , AAWSA Program Ma…

UNCLASSIFIED / /F@R-GFEECIRE USE ONCT Contents DL. IMtroduction 2... cccsccscsensenesnsenesennesnensescenacaneneuananscanecersneneuenauauenauanameneneneusueneuenanenen iv 2. The Key Question: How Far are They ? ......c..sescnesesccusscerscesusccurerucarsreceverererspessrer 4 3. Computing A By Virtue of the Drake Equation (1961) .......cccssssenccencnssenceseceeneneeas 7 4, The Drake Equation is Over-Simplified ..........scscsesuserersceresesereeses wreresares evesesenenes 10 5. The Statistical Drake EQuations 1... .1cccccccnsscscescseseennesseeeeneeeesnseeencaneneesnauneanseenanens 11 6. Solvi…

UNCLASSIFIED/ /SQ3.Q05516L4ic)GE-@ Piao An Introduction to the Statistical Drake Equation i. Introduction SETI (an acronym for “Search for Extraterrestrial Intelligence”) is a relatively new branch of scientific research, having begun only in 1959. Its goal is to ascertain whether alien civilizations exist in the universe, how far from us they exist, and possibly how much more advanced than us they may be. As of 2009, the only physical tools we know that could help us get in touch with aliens are the electromagnetic waves an alien civilization could emit and we could detect. This forces us to …

UNCLASSIFIED / /$0-2a@EE1GGAir UG Ohi The thickness of the Galactic Disk at half-way from its center, Again. IS AbOUt 16,000 ly. The volume of the galaxy may then be approximated as the volume of the corresponding cylinder, i.e. 2 Veatawy = F Reata h. (1) Now consider the sphere around us having a radius r. The volume of such a sphere is (2) Vou Sphere = Our_ Sphere 3 2 4 ET_Distance ) Ps. — In the last equation, we had to divide the distance “ET_Distance” between ourselves and the nearest ET civilization by 2 because we are now going to make the unwarranted assumption that aff ET civilization…

UNCLASSIFIED / /®@f OF FIGHirUGrOM pi YORE raoeh ET_Distance(¥) = +22" = c (5) YN oN where the positive constant C is defined by C= V6 Révatesy "Gatasy ¥ 28845. light years . (6) Equations (5) and (6) are the starting point to understand the origin of the Drake equation that we discuss in detail in Section 3 of this paper. Let us just complete this section by pointing out three different numerical cases of the distance law (5): * We know that we exist, so WV may not be smaller than 1, i.¢., N21. Suppose then that we are alone in the galaxy, i.e., that V=1. Then the distance law (5) yields as d…

UNCLASSIFIED/ / Average DISTANCEof the nearest ET civilization vs. the ASSUMED NUMBER of ET civilizations in the Gak pt tT | tT pj | ft | tt | ff | te Ai | 2006 WAL 1506 erage DISTANCE of the civilization nearest to us in LIGHT YEARS Avera iS AL S 0 0 1ogooo 200000 200000 400000 500000 600000 700000 S00000 $00000 1000000 ASSUM ED NUMBER of civilizations in the Galaxy (that is, N in the Drake equation) Figure 1. DISTANCE LAW; i.e., the Average Distance (plot along the vertical axis in light years) Versus the NUMBER of Communicating Civilizations ASSUMED to Exist in the Galaxy Right Now 3. Compu…

UNCLASSIFIED / /@8-0-E5IGHAL-UGE-OaiaS It is very hard to be sure. There may be several impediments to the evolution of a technical civilization. Planets may be rarer than we think. Perhaps the origin of life is not so easy as our laboratory experiments suggest. Perhaps the evolution of advanced life forms is improbable. Or it may be that complex life forms evolve more readily, but intelligence and technical societies require an unlikely set of coincidences — just as the evolution of the human species depended on the demise of the dinosaurs and the ice- age recession of the forests in whose tr…