Aliens from our own Solar System
A viral SETI argument says we should search the Moon and Earth's past before looking to distant stars.
A provocative post titled "Aliens from our own Solar System" has gone viral on the rationalist forum LessWrong, challenging conventional SETI (Search for Extraterrestrial Intelligence) priorities. Author RomanS argues that the probability of encountering extraterrestrial life is higher within our Solar System than from interstellar distances, given the known properties of life and our cosmic neighborhood. The core premise is that Earth has been a life-producing engine for 4 billion years, with material exchange possible with nearby bodies like the Moon, and that intelligence has evolved here at least once, suggesting it could have happened elsewhere in the System.
The post makes a specific case for two search directions: investigating the deep past on Earth, particularly around troodontid dinosaurs—a bird-like species with large brains and social structures that went extinct 66 million years ago—and probing the interiors of water-harboring celestial bodies. The Moon is highlighted as a top priority due to its geological stability and the potential preservation of artifacts from a past technological civilization. The argument also explores the possibility of an active, undetected civilization in environments like Europa's subsurface ocean, noting the detection asymmetry such a location would create.
This thought experiment shifts the focus from traditional radio telescope surveys of distant stars to a more local, archaeological, and planetary science-based approach to the search for intelligence. It underscores that our own planet's history and our celestial backyard may hold more immediate answers to the question of whether we are alone than the vast reaches of the galaxy.
- The post argues that Earth's 4-billion-year history of producing life and intelligence (like the troodontid dinosaurs 66M years ago) makes a local origin for ETs more probable than an interstellar one.
- It identifies the Moon's subsurface and other Solar System bodies with potential liquid water (Europa, Mars) as top search priorities for signs of past or present technological civilizations.
- The core implication is a paradigm shift for SETI, suggesting we should search for artifacts and evidence locally and in Earth's geological record before assuming aliens must come from light-years away.
Why It Matters
Reframes the search for alien intelligence from a deep-space radio hunt to a local archaeological and planetary science endeavor with nearer-term potential.