Avi Loeb

Brief Biography

Abraham "Avi" Loeb was born on 26 February 1962 in Beit Hanan, Israel. He earned his PhD in plasma physics from the Hebrew University of Jerusalem and joined Harvard University in 1993, where he became the Frank B. Baird Jr. Professor of Science and chaired the astronomy department for nine years — one of the most prestigious academic posts in astrophysics. He has published over 700 peer-reviewed papers on cosmology, black holes, the first stars and galaxies, and astrobiology.

Loeb entered the UAP and interstellar artefact debate with his 2021 book Extraterrestrial: The First Sign of Intelligent Life Beyond Earth, in which he argued that the 2017 interstellar object ʻOumuamua — the first known interstellar object to transit the solar system — showed properties inconsistent with any known natural phenomenon and consistent with an artificial light sail. The book became a bestseller and made Loeb the most credentialled mainstream scientist to publicly advocate for the possibility that ET technology had visited our solar system.

ʻOumuamua and the Artificial Artefact Hypothesis

Loeb's argument about ʻOumuamua rests on several anomalous properties. The object showed non-gravitational acceleration as it departed the solar system — it was moving faster than pure gravitational dynamics predicted, as if being pushed by sunlight. For this to work via solar radiation pressure, the object would need to be extremely thin relative to its mass — a ratio consistent with an artificial light sail but inconsistent with any known natural object. Additionally, ʻOumuamua tumbled erratically, showed no cometary outgassing despite being in the inner solar system, and had an extreme aspect ratio (elongated or flat) unlike any known asteroid or comet.

The mainstream astronomical community's response was largely dismissive — proposing alternatively that the non-gravitational acceleration was from hydrogen outgassing (which Loeb argued was not observable and physically implausible) or other natural mechanisms. Loeb countered that the scientific community's resistance to even investigating the artificial hypothesis was an example of the social dynamics of institutional science overriding methodological openness.

The Galileo Project

In 2021, Loeb founded the Galileo Project — a Harvard-based scientific initiative to systematically search for evidence of extraterrestrial technological artefacts. The project deploys telescopes and sensors to search for ʻOumuamua-like interstellar objects, study UAP using scientific instruments, and develop the methodological frameworks for ET artefact detection. In 2023, Loeb led an expedition to recover spherules from the ocean floor at the site of the 2014 meteor impact (CNEOS 2014-01-08) — an interstellar fireball whose anomalous velocity made it a potential artefact candidate. He claimed the recovered spherules showed unusual isotopic ratios.

Loeb's significance in the UAP/interstellar intelligence field is as a credibility bridge: his institutional standing as a Harvard professor with 700+ peer-reviewed papers makes it impossible for the scientific community to simply dismiss the questions he raises. His willingness to publicly challenge the social dynamics of scientific scepticism — arguing that the taboo against investigating ETI hypotheses reflects social fear rather than scientific reasoning — has opened space for more mainstream engagement with these questions.