1969 & ndash ; Project Blue Book : The United States Air Force closes its study of UFOs, stating that sightings were generated as a result of '' A mild form of mass hysteria, Individuals who fabricate such reports to perpate a hoax or seek publicity, psychopathological persons, and misidentification of various conventional objects ".
1908 - Willard Frank Libby, physicien et chimiste américain -LRB- d. 1980 -RRB-