Avi Loeb

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Avi Loeb

Template:Infobox scientist Abraham "Avi" Loeb (born February 26, 1962) is an Israeli-American theoretical physicist and cosmologist, the Frank B. Baird Jr. Professor of Science at Harvard University, and founding director of Harvard's Black Hole Initiative. He chaired Harvard's Department of Astronomy from 2011 to 2020 and is best known outside academia for arguing that anomalous interstellar objects — including ʻOumuamua — may be of technological origin, and for founding the Galileo Project to search systematically for physical evidence of extraterrestrial technology. His artificial-origin proposals have been widely criticised by other astronomers and remain a minority position within the astronomical community.

Early life and education

Loeb was born on 26 February 1962 in Beit Hanan, Israel, to a farming family. He grew up on a farm and served in the Israeli military — including a paratrooper unit — before completing his education at the Hebrew University of Jerusalem, where he received a BSc in physics and mathematics in 1983, an MSc in physics in 1985, and a PhD in plasma physics in 1986 at age 24. An arrangement enabled by the Strategic Defense Initiative ("Star Wars") program brought him to the United States.

Academic career

From 1988 to 1993 Loeb was a long-term member of the Institute for Advanced Study in Princeton; in 1993 he joined Harvard University as an assistant professor, gaining tenure in 1996 and being named the Frank B. Baird Jr. Professor of Science in 2012. He chaired Harvard's Department of Astronomy from 2011 to 2020 and founded Harvard's Institute for Theory and Computation, which he continues to direct. He chaired the Board on Physics and Astronomy of the National Academies of Sciences, Engineering, and Medicine, and in 2016 founded Harvard's Black Hole Initiative.

Research

Loeb's published research spans the formation of the first stars and galaxies, the evolution of the intergalactic medium, the imaging of supermassive black holes, gravitational lensing, the tidal disruption of stars, and the conditions for habitability in the early universe — including a 2013 proposal that during a "habitable epoch" between 10 and 17 million years after the Big Bang the cosmic microwave background could have warmed planets to liquid-water temperatures regardless of distance from a host star.

ʻOumuamua and the artificial-origin hypothesis

Main article:

ʻOumuamua

In 2017, the Pan-STARRS survey telescope in Hawaii detected ʻOumuamua, the first interstellar object ever identified passing through the Solar System. Loeb and colleagues found the object anomalous on several grounds: its brightness varied by a factor of ten during tumbling — consistent with a flat, pancake-like shape — and it accelerated away from the Sun without any detectable cometary outgassing. In a 2018 paper co-authored with Harvard postdoctoral researcher Shmuel Bialy, Loeb proposed that the anomalous acceleration was consistent with radiation pressure acting on a thin artificial light sail. He noted also an unusual sun-facing jet feature visible in Hubble Space Telescope imaging that conventional cometary models did not straightforwardly explain.

Most astronomers rejected the artificial interpretation, maintaining that natural explanations — including a dark or inert comet lacking a visible tail — were far more plausible. By 2021, the international ʻOumuamua group had concluded the object was consistent with a naturally occurring body — possibly composed of nitrogen ice fragmented from a Pluto-like planet around another star. Loeb argued that dismissing the technological hypothesis without investigation repeated the institutional errors he associated with the historical treatment of Galileo Galilei. He published his case for public audiences in his book Extraterrestrial: The First Sign of Intelligent Life Beyond Earth (2021).

CNEOS 2014-01-08 (IM1) expedition

Loeb argued that a 2014 fireball logged by the U.S. CNEOS catalog (designated IM1) was of interstellar origin based on its high speed, and in 2023 he led a Pacific seabed expedition that recovered millimetre-scale spherules he characterized as potentially alloy-rich material from "an extraterrestrial starship." Critics, including geophysicists who re-examined the seismic data, argued the search location had been derived from a seismic signal that was actually generated by a passing truck rather than the meteor's airburst, and that the spherules were consistent with terrestrial industrial pollution.

The Galileo Project

Main article:

Galileo Project

In July 2021, Loeb publicly launched the Galileo Project, a Harvard-based scientific initiative to search for physical evidence of extraterrestrial technological objects (unidentified aerial phenomena, interstellar objects, and possible alien satellites in Earth orbit). Initial funding reached $1.755 million from private donors — primarily individuals who had made their wealth in industrial chemistry and manufacturing.

The project's central methodological commitment is to avoid classification problems by collecting only open-source, publicly accessible data to be published in peer-reviewed journals. Loeb drew an explicit contrast with military-funded UAP programs: "The Pentagon has a $22-million budget to study UAPs, and I'm not sure what that produced," said Galileo collaborator Amir Siraj; "The hope is that with less money we will be able to produce better results."

The project built a working observatory at Harvard and was assembling additional stations in Pennsylvania and Nevada as of early 2025. Loeb described three research fronts: continuous sky-monitoring telescope arrays; a search for unusual artificial objects in Earth orbit; and follow-up study of interstellar objects flagged by wide-field survey telescopes such as the Vera C. Rubin Observatory.

3I/ATLAS (2025)

Main article:

3I Atlas

In July 2025, Loeb applied the same analytical framework to 3I Atlas, the third interstellar object detected — estimating it at least a million times more massive than ʻOumuamua, with anomalies including sun-facing jets, a retrograde trajectory aligned within 5 degrees of the planetary plane, and unusual composition. He published twelve papers on the object (eleven co-authored) and faced public criticism from astronomers including Brian Cox and Jason Wright. NASA and the European Space Agency confirmed the object's coma contained water — typical of a comet — and rejected the technological hypothesis. Loeb argued that even at 99% confidence the object is natural, the 1% chance of alien technology — multiplied by its civilisational impact — warrants rigorous investigation: "when you deal with something coming to our backyard, you can't just say 99% it's a rock and therefore we shouldn't even worry about it."

Scientific philosophy and the "cosmic modesty" argument

Loeb argues that the mainstream astronomy community applies a double standard: it is willing to fund a $10 billion search for microbial chemical signatures on exoplanets while providing no federal funding for the search for extraterrestrial intelligence, despite the far greater potential implications of the latter. His underlying argument is a version of the Copernican principle: if complex chemistry produces life on Earth, similar processes are likely to have produced intelligence on billions of other worlds that formed long before the Sun, and claiming otherwise is a form of cosmic arrogance. He describes the disposition he advocates as approaching the universe with "curiosity, but also modesty" — acknowledging that Earth and humanity are not cosmically central.

Loeb also argues that classified military UAP programs are an inappropriate vehicle for answering scientific questions, since their data cannot be publicly evaluated. He deliberately designed the Galileo Project to use only unclassified, openly published data so results cannot be suppressed.

Astronomical community response

Outside Loeb's circle, astronomers are largely sceptical of his specific claims while crediting the Galileo Project's methodological commitment to systematic public data collection. Pennsylvania State University astrophysicist Jason Wright — a SETI advocate — said he appreciated that Loeb intended "to do some systematic data collection and study it with a clean sheet," while also noting the low probability of finding anything. Astronomer Lucianne Walkowicz of the Adler Planetarium said the project "can be a very positive thing" in legitimizing investigation, but criticized Loeb's self-presentation as an outsider: "He has nothing at risk. He's a tenured Harvard professor." Skeptical investigator Mick West observed: "Is he a voice crying out the truth in the wilderness, or is he a bit of a crank? Time will tell." Arizona State University astrophysicist Steve Desch characterised some of Loeb's published claims as "ridiculous sensationalism" that "pollutes good science," and Open University planetary scientist Monica Grady called the IM1 spherule evidence "rather shaky," pointing to terrestrial industrial pollution.

Awards and honours

Selected publications

See also

References

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