Avi Loeb

Loeb was born in 1962 and raised on his family’s farm in Beit Hanan in central Israel. As a youth he was fascinated by philosophy and on weekends would drive a tractor into the hills to spend hours reading existentialist philosophers such as Jean-Paul Sartre and Albert Camus.⁠[1]

At 18 he was among the first cadets of the Israel Defense Forces’ elite Talpiot program, founded in 1979, earning a bachelor’s degree in mathematics and physics while rotating through military units; he later chose to spend the rest of his service doing research at the Soreq Nuclear Research Center.⁠[2]

He studied at the Hebrew University of Jerusalem from 1980 to 1986, earning a PhD in physics at age 24; from 1983 to 1988 he led the first international project supported by the US Strategic Defense Initiative, and from 1988 to 1993 he was a long-term member of the Institute for Advanced Study in PrincetonPrinceton UniversityPrinceton University is a private university and Ivy League member in Princeton, New Jersey. Chartered on October 22, 1746 as the College of New Jersey, it moved to Princeton in 1756 and adopted its present name in 1896. Undergraduate education leads to A.B. and B.S.E. degrees and emphasizes small-group discussion, independent research and residential college life. Graduate education spans the humanities, social sciences, natural sciences and engineering. As of October 2026, Christopher L. Eisgruber was president. Its 2026–27 operating budget was $3.407 billion, including $342 million for undergraduate aid.Open the full entry.⁠[3]

In 1993 he joined Harvard University’s astronomy department as an assistant professor. He is married to political scientist Ofrit Liviatan; they have two daughters and live in the Boston area.⁠[2]

Since 2007 he has directed the Institute for Theory and Computation within the Harvard-Smithsonian Center for Astrophysics.⁠[4]

From 2011 to 2020 he chaired Harvard’s astronomy department, its longest-serving chair; in 2012 TIMETIMETIME is an American newsmagazine and media brand founded by Henry Luce and Briton Hadden, which published its first issue on March 3, 1923; it is headquartered in New York and known for its Person of the Year selection and the TIME100 list. Since 2018 it has been personally owned by Marc and Lynne Benioff; its current Chief Executive Officer is Jessica Sibley, and its Editor-in-Chief is Sam Jacobs.Open the full entry magazine named him one of the 25 most influential people in space.⁠[5]

From 2016 to 2021 he was founding director of Harvard’s Black Hole Initiative, an interdisciplinary research center.⁠[4]

On April 12, 2016, Yuri Milner announced Breakthrough Starshot, a $100 million program to develop postage-stamp-sized “nanocrafts” whose sails would be pushed by Earth-based lasers toward Alpha Centauri at one-fifth the speed of light. Loeb took part in the press conference and became chair of its advisory committee.⁠[6]

In November 2018 he and Shmuel Bialy published a paper in The Astrophysical Journal Letters arguing that the anomalous acceleration of ‘Oumuamua, the first known interstellar object, found in 2017, could be explained by solar radiation pressure, in which case it would be less than 1 mm thick and might be a light sail made by an alien civilization; they called this an “exotic scenario.” Other teams had attributed the acceleration to comet-like outgassing.⁠[7]

In July 2019 the ‘Oumuamua ISSI Team, 14 researchers including Michele Bannister and Karen Meech, published a review in Nature Astronomy concluding that all observations are consistent with a purely natural origin for ‘Oumuamua.⁠[8]

In April 2020 he was named to the White House President’s Council of Advisors on Science and Technology (PCAST). He said he was delighted to join at a time when scientists must help fight COVID-19.⁠[5]

In January 2021 he published Extraterrestrial: The First Sign of Intelligent Life Beyond Earth, arguing that ‘Oumuamua was an alien craft with a light sail and criticizing the scientific community as too closed-minded about searching for alien intelligence; the book also recounts his upbringing on an Israeli farm and his move from philosophy to physics.⁠[9]

Publishers Weekly called the book a “contentious manifesto,” finding its advice on locating inhabited exoplanets often ingenious but its attack on astronomical orthodoxy less cogent.⁠[10]

On January 14, 2021, he appeared on episode 154 of the Lex FridmanLex FridmanLex Fridman is a Soviet-born, US-raised computer scientist and podcast host who works as an MIT research scientist on human-AI interaction and autonomous driving. His Lex Fridman Podcast is known for hours-long conversations with guests including heads of state and technology leaders.Open the full entry Podcast, discussing whether we are alone in the universe, ‘Oumuamua, the Drake equation, UFO sightings, Breakthrough Starshot, black holes, Stephen Hawking, dark matter and memories of his parents.⁠[11]

On July 26, 2021, he announced the Galileo Project, which he heads, to search systematically with networked small ground-based telescopes for possible extraterrestrial technological objects near Earth and in space, including the unidentified aerial phenomena described in a US government report, and to develop algorithms to find interstellar objects in LSST data. He said donations of $1.75 million arrived within weeks.⁠[12]

In June 2023 the Galileo Project team, aboard the ship Silver Star, dragged a magnetic sled across the seafloor about 85 km off Manus Island, Papua New Guinea, seeking fragments of the meteor CNEOS 2014-01-08 (which he calls IM1) that entered the atmosphere on January 8, 2014, and recovered at least 50 sub-millimeter metallic spherules. Loeb and his student Amir Siraj had earlier argued that IM1 came from outside the solar system, and he raised the possibility that it was technological.⁠[13]

In August 2023 he published Interstellar: The Search for Extraterrestrial Life and Our Future in the Stars, calling for observatories dedicated to small near-Earth objects and more government funding. Publishers Weekly found questionable assumptions in it and judged it unlikely to sway skeptics.⁠[14]

Loeb had described five “BeLaU” spherules rich in beryllium, lanthanum and uranium as anomalous. In October and November 2023, Patricio Gallardo of the University of Chicago argued that their composition matches coal ash, and Steven Desch and Alan Jackson argued that an interstellar IM1 would have almost entirely vaporized in the atmosphere. Loeb replied on his blog that the critics had not examined the samples directly and that 93% of the material had yet to be analyzed.⁠[15]

In March 2024, Benjamin Fernando of Johns Hopkins University presented an analysis at the Lunar and Planetary Science Conference arguing that the Manus Island seismic signal used to narrow the search came from a passing truck, so the area searched was not on the meteor’s path. Loeb countered that the search relied mainly on US Department of Defense CNEOS data and that the same region would have been surveyed without the seismic data.⁠[16]

On July 16, 2025, he, Adam Hibberd and Adam Crowl posted the preprint “Is the Interstellar Object 3I/ATLAS Alien Technology?” on arXiv, describing it as “largely a pedagogical exercise” and hypothesizing that the third known interstellar object could be technological and possibly hostile.⁠[17]

Most astrophysicists see 3I/ATLAS as showing the hallmarks of an icy comet; Chris Lintott of Oxford called the artificial-origin suggestion “nonsense on stilts.” Loeb wrote on his blog that the most likely outcome is that it is a natural interstellar object, probably a comet.⁠[18]

In July 2026 he was appointed to lead a new science advisory team supporting the UAP Governance Board overseen by the Office of the Director of National Intelligence, which studies national security risks from unidentified anomalous phenomena. He said he starts from the assumption that the phenomena are the work of humans.⁠[19]

Steve Desch said that with Loeb in charge no one would get closer to answering these questions; Sean Kirkpatrick, who previously investigated UAP at the Pentagon, said Loeb lacks national security experience. Loeb said his critics lack the imagination to consider new ideas.⁠[19]

Personal website: Public link: https://lweb.cfa.harvard.edu/~loeb/ (opens in a new window)⁠[20]

Medium: Public account: https://avi-loeb.medium.com/ (opens in a new window)⁠[21]

Harvard University: Official website: https://www.harvard.edu/ (opens in a new window)⁠[4]

Institute for Advanced Study: Official website: https://www.ias.edu/ (opens in a new window)⁠[3]

Black Hole Initiative: Official website: https://bhi.fas.harvard.edu/ (opens in a new window)⁠[4]

Galileo Project: Official website: https://projects.iq.harvard.edu/galileo (opens in a new window)⁠[4]