Two interstellar searchers for alien life, after endless failures, must confront what went wrong in their understanding of Drake's equation, the famed formula that allegedly estimates the odds of interstellar life. The mathematical aspects are explicit.

Published in Greg Bear and M H Greenberg (eds) NEW LEGENDS, reprinted in Orson Scott Card (ed) MASTERPIECES: THE BEST SCIENCE FICTION OF THE CENTURY.

This book is more of an emotional trip than anything else. While Drake's equation is used in explaining the background (essentially -- how order of magnitude analysis can be completely wrong), the book's main draw is man's realization that he is completely alone in the universe.

One was perhaps the most disturbing story I have ever read. I can handle the idea of creepy, abducting aliens, but the thought that the universe is some kind of vast desert is extremely frightening. I guess the enormity of our galaxy makes the plot of One possible; the Drake Equation posits only numbers of intelligent life, not spatial distribution. Thanks for the info.. It's a nice thought-experiment. Take care.

This story is indeed very disturbing, which was why it took 20 years for Effinger to find a publisher. No magazine editor wanted to touch it because the theme of the story -- that we are entirely alone in the universe -- was the antithesis to what every SF fan wanted to read. Gratefully Greg Bear acquired it for his New Legends anthology. The story has since been reprinted twice: in Orson Scott Card's anthology Masterpieces: The Best Science Fiction of the 20th Century, and more recently in the George Alec Effinger collection Live! From Planet Earth (Golden Gryphon Press, 2005). "One" is indeed one of the best SF stories of the 20th century! [Note: a bit of disclosure: I acquired all three Effinger collections for Golden Gryphon Press, including Live!]