Extraterrestrial Hypothesis
Extraterrestrial Hypothesis The extraterrestrial hypothesis (ETH) proposes that some unidentified flying objects (UFOs) are best explained as being physical spacecraft occupied by extraterrestrial life or non-human aliens, or non occupied alien probes from other planets visiting Earth. Etymology Origins of the term extraterrestrial hypothesis are unknown, but use in printed material on UFOs seems to date to at least the latter half of...