Why would ETI colonize the ENTIRE galaxy, especially systems already occupied?
Persistence solves Fermi Paradox but challenges SETI projects, by Osame Kinouchi:
http://arxiv.org/PS_cache/cond-mat/pdf/0112/0112137.pdf
There is an excellent collection of papers and sites on the subject here:
http://www.faughnan.com/setifail.html
David Brin offers an examination and solutions to the Fermi Paradox here in
his paper, The Great Slience:
http://brin-l.stock-consulting.com/downloads/silence.pdf
