Caelum Incognitum — The interactive encyclopedia of ufology
Extraterrestrial hypothesis (ETH)
Hypotheses & theories
The thesis that some UFOs are craft of an extraterrestrial civilization. It is the best-known hypothesis among the general public, defended notably by Donald Keyhoe, Stanton Friedman and, in his own way, Allen Hynek. It supposes crossing vast interstellar distances and remains without proof: it is tested by well-documented cases, never by a recognized artifact.
See also
- Fermi paradox
- Interdimensional hypothesis
- Cryptoterrestrial hypothesis
- Donald Keyhoe (1897-1988)
- Stanton Friedman (1934-2019)
- Alcubierre drive
- Interstellar distances
- Acronyms to know
- “Estimate of the Situation” (1948)
- NHI (non-human intelligence)
- Time-travel hypothesis
- Ancient astronauts hypothesis
- COMETA report
- Panspermia
- Bracewell probe