Editing Fermi paradox (section)

=== Conjectures about interstellar probes ===
{{Further|Hart–Tipler conjecture|Von Neumann probe|Bracewell probe}}
The [[Hart–Tipler conjecture]] is a form of [[contraposition]] which states that because no interstellar probes have been detected, there likely is no other intelligent life in the universe, as such life should be expected to eventually create and launch such probes.<ref name="Gray2015">{{cite journal |last1=Gray |first1=Robert H. |title=The Fermi Paradox Is Neither Fermi's Nor a Paradox |journal=Astrobiology |date=March 2015 |volume=15 |issue=3 |pages=195–199 |doi=10.1089/ast.2014.1247|pmid=25719510 |arxiv=1605.09187 |bibcode=2015AsBio..15..195G }}</ref><ref name="AliensSpaceTime2020">{{cite book|last1=Dick |first1=Steven J. |title=Space, Time, and Aliens: Collected Works on Cosmos and Culture |chapter=Bringing Culture to Cosmos: Cultural Evolution, the Postbiological Universe, and SETI |date=2020 |pages=171–190 |doi=10.1007/978-3-030-41614-0_12 |chapter-url=https://link.springer.com/chapter/10.1007/978-3-030-41614-0_12 |access-date=18 October 2022 |publisher=Springer International Publishing |isbn=978-3-030-41613-3 |s2cid=219414685 |language=en}}</ref> Self-replicating probes could exhaustively explore a galaxy the size of the Milky Way in as little as a million years.<ref name="Hart"/> If even a single civilization in the Milky Way attempted this, such probes could spread throughout the entire galaxy. Another speculation for contact with an alien probe—one that would be trying to find human beings—is an alien [[Bracewell probe]]. Such a hypothetical device would be an autonomous space probe whose purpose is to seek out and communicate with alien civilizations (as opposed to von Neumann probes, which are usually described as purely exploratory). These were proposed as an alternative to carrying a slow [[speed-of-light]] dialogue between vastly distant neighbors. Rather than contending with the long delays a radio dialogue would suffer, a probe housing an [[artificial intelligence]] would seek out an alien civilization to carry on a close-range communication with the discovered civilization. The findings of such a probe would still have to be transmitted to the home civilization at light speed, but an information-gathering dialogue could be conducted in real time.<ref>{{cite journal| last1=Bracewell| first1=R. N.| title=Communications from Superior Galactic Communities| journal=Nature| volume=186| issue=4726| pages=670–671| date=1960| doi=10.1038/186670a0| bibcode = 1960Natur.186..670B | s2cid=4222557}}</ref>

Direct exploration of the Solar System has yielded no evidence indicating a visit by aliens or their probes. Detailed exploration of areas of the Solar System where resources would be plentiful may yet produce evidence of alien exploration,<ref name="AsteroidBelt">{{cite journal |author=Papagiannis, M. D. |title=Are We all Alone, or could They be in the Asteroid Belt? |journal=[[Quarterly Journal of the Royal Astronomical Society]] |volume=19 |pages=277–281 |date=1978 |bibcode = 1978QJRAS..19..277P }}</ref><ref>{{cite news |title=Extraterrestrial Intelligence in the Solar System: Resolving the Fermi Paradox |author=Robert A. Freitas Jr. |journal=[[Journal of the British Interplanetary Society]] |volume=36 |date=November 1983 |pages=496–500 |url=http://www.rfreitas.com/Astro/ResolvingFermi1983.htm |bibcode=1983JBIS...36..496F |access-date=November 12, 2004 |archive-url=https://web.archive.org/web/20041208080419/http://www.rfreitas.com/Astro/ResolvingFermi1983.htm |archive-date=December 8, 2004 |url-status=live }}</ref> though the entirety of the Solar System is relatively vast and difficult to investigate. Attempts to signal, attract, or activate hypothetical Bracewell probes in Earth's vicinity have not succeeded.<ref>{{cite journal| last1=Freitas| first1=Robert A Jr|last2=Valdes|first2=F|doi=10.1016/0094-5765(85)90031-1|title=The search for extraterrestrial artifacts (SETA)| date=1985 |pages=1027–1034| issue=12| volume=12| journal=Acta Astronautica| bibcode = 1985AcAau..12.1027F | citeseerx=10.1.1.118.4668}}</ref>