ABSTRACT: The complete text of A.D.Sakharov's letter of August 8, 1971, concerning his ideas on Search for Extraterrestrial Intelligence, is published. ... Few people know that in Andrei Dmitriyevich Sakharov's varied research and social activities, there was an episode connected with Search for Extraterrestrial Intelligence (SETI); thanks to that, he has left for us a bit of his ideas on the subject. ... Is there any danger in receiving information from an extraterrestrial civilization? ...

SETI . ... 1.1 4 в 109 [1] Homo (4 - 5) в 106 [2]. ... Homo sapiens - , . ... Homo. 7. ­ (2 - 1, 5) в 106 [21]. ... Homo erecrus. 9. ­ 0, 4 в 106 [23]. Homo - - Homo erectus. ... 1981 [30]. . ... R (T ) (Star Formation Rate, SFR). ... B (M , ) LC ( ), , , 39 Number of civilizations Self-consistent origin of life 3500 3000 2500 2000 1500 1000 500 00 2 4 6 8 10 12 14 Post transition civilizations Uniform single-planets origin of life 16 18 20 22 Time, Gyr . ... Lexington Bo oks, 2003. ... 2001. ...