Documents / Report
This Defense Intelligence Agency reference document, dated 11 March 2010, is one of the advanced technology reports produced in FY 2009 under the Advanced Aerospace Weapon System Applications (AAWSA) program. It introduces the Statistical Drake Equation, which replaces each factor of Frank Drake's 1961 equation with a uniform random variable to estimate how far away the nearest extraterrestrial civilization is. In the worked example, there is a 75% probability that the nearest civilization lies between 1,361 and 3,979 light years from Earth.
“The Advance”6 pages
UNCLASSIFIED// FOK OFFI@Itllt ~&Ii SU.blf Table 2. Summary of the Properties of the Probability Distribution That Applies to the Random Variable ET_Distance Yielding the (average) Distance Between Any Two Neighboring Communicating Civilizations in the Galaxy Random variable Probability distribution Probability density function Numerical constant C related to the Milky Wav size Mean value Variance Standard deviation All the moments, i.e. k-th moment Mode ( = abscissa of the log normal peak) Value of the Mode Peak Median ( = fifty-fifty probability value for N) Skewness Kurtosis Expression of μin terms of the lower (ai) and upper (bi) limits of the Drake uniform input random variables Di Expression of cr 2 in terms of the lower (ai) and upper (bi) limits of the Drake uniform inout random variables Di 20 ET_Distance between any two neighboring ET civilizations in galaxy assuming they are UNIFORMLY distributed throughout the whole oalaxv volume. Unnamed 3 /ET Dtstan,.,(r) = - - ' JI ,,- (Er_ DiS lancc) =Ce '.1e 18 ! /' k' a- (Ef_DiS(ance') = ck e :i e 18 - - r,wdc = rp,ak = Ce J e '! Peak Value of .r~_I_D1>1'm«:(r) = ] JI (T- = fET D,,urn«· (,.nwk l = - ·e.1,elS c5;cr " me<lian = m = Ce -1 K .:!....':_ " ~ --'-=e '! +2e :i +3e 'J -6 (K, )' UNCLASSIFIED//1"91!. 91"1"!!!111L tl!!I! 911Li
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 55 pages are in the text index: search them above, or from the library's search.