Loeb in April 2020
February 26, 1962
Abraham "Avi" Loeb (Hebrew: אברהם (אבי) לייב; born February 26, 1962) is an Israeli-American theoretical physicist who works on astrophysics and cosmology. Loeb is the Frank B. Baird Jr. Professor of Science at Harvard University. He had been the longest serving Chair of Harvard's Department of Astronomy (2011–2020), Founding Director of Harvard's Black Hole Initiative (since 2016) and Director of the Institute for Theory and Computation (since 2007) within the Harvard-Smithsonian Center for Astrophysics.
Loeb is a fellow of the American Academy of Arts and Sciences, the American Physical Society, and the International Academy of Astronautics. In July 2018, he was appointed as chair of the Board on Physics and Astronomy (BPA) of the National Academies, which is the Academies' forum for issues connected with the fields of physics and astronomy, including oversight of their decadal surveys.
In June 2020, Loeb was sworn in as a member of the President's Council of Advisors on Science and Technology (PCAST) at the White House. In December 2012, TIME magazine selected Loeb as one of the 25 most influential people in space. In 2015, Loeb was appointed as the Science Theory Director for the Breakthrough Initiatives of the Breakthrough Prize Foundation. In 2018, he attracted media attention for suggesting that alien space craft may be in our solar system, using the anomalous behavior of 'Oumuamua as an example. In 2019, and together with his Harvard undergraduate student, Amir Siraj, Loeb reported discovering a meteor that potentially originated outside the Solar System.
Loeb was born in Beit Hanan, Israel in 1962. He took part in the national Talpiot program before receiving a PhD in plasma physics, at age 24, from the Hebrew University in Jerusalem, in 1986. From 1983 to 1988, he led the first international project supported by the U.S. Strategic Defense Initiative. Between 1988 and 1993, Loeb was a long-term member at the Institute for Advanced Study in Princeton, where he started to work in theoretical astrophysics. In 1993, he moved to Harvard University as an assistant professor in the department of astronomy, where he was tenured three years later.
Loeb has written eight books and authored or co-authored about 800 papers on a broad range of research areas in astrophysics and cosmology, including the first stars, the epoch of reionization, the formation and evolution of massive black holes, the search for extraterrestrial life, gravitational lensing by planets, gamma-ray bursts (GRBs) at high redshifts, 21-cm cosmology, the use of the Lyman-alpha forest to measure the acceleration/deceleration of the universe in real time (the so-called "Sandage–Loeb test"), the future collision between the Milky Way and Andromeda galaxies, the future state of extragalactic astronomy, astrophysical implications of black hole recoil in galaxy mergers, tidal disruption of stars, and imaging black hole silhouettes. In 2010, he wrote a textbook entitled How Did the First Stars and Galaxies Form?
In 1992, Loeb suggested, with Andy Gould, that exoplanets could be detected through gravitational microlensing. In 1993, he proposed the use of the C+ fine-structure line to discover galaxies at high redshifts. In 2005, he predicted, in a series of papers with his postdoc at the time, Avery Broderick, how a hot spot in orbit around a black hole would appear; their predictions were confirmed in 2018 by the GRAVITY instrument on the VLT which observed a circular motion of the centroid of light of the black hole at the center of the Milky Way, Sagittarius A*. In 2009, Broderick and Loeb predicted the shadow of the black hole in the giant elliptical galaxy Messier 87, which was imaged in 2019 by the Event Horizon Telescope. In 2013, a report was published on the discovery of the "Einstein Planet" Kepler-76b, the first Jupiter size exoplanet identified through the detection of relativistic beaming of its parent star, based on a technique proposed by Loeb and Gaudi in 2003. In addition, a pulsar was discovered around the supermassive black hole, Sagittarius A*, following a prediction by Pfahl and Loeb in 2004. Also, a hypervelocity star candidate from the Andromeda galaxy was discovered, as predicted by Sherwin, Loeb, and O'Leary in 2008. Together with his postdoc, James Guillochon, Loeb predicted the existence of a new population of stars moving near the speed of light throughout the universe. Together with his postdoc John Forbes and Howard Chen of Northwestern University, Loeb made another prediction that sub-Neptune sized exoplanets have been transformed into rocky super-Earths by the activity of Milky Way's central supermassive black hole Sagittarius A*.
In collaboration with Dan Maoz, Loeb demonstrated in 2013 that biomarkers, such as molecular oxygen (O
2), can be detected by the James Webb Space Telescope (JWST) in the atmosphere of Earth-mass planets in the habitable zone of white dwarfs.
Together with his former student Steve Furlanetto, Loeb published a textbook, The First Galaxies in the Universe.
In 2013, Loeb introduced the new concept of "The Habitable Epoch of the Early Universe", and mentored Harvard undergraduate, Henry Lin, in the study of industrial pollution on exoplanets as a new method to search for extraterrestrial civilizations.
In December 2017, Loeb cited ʻOumuamua's unusually elongated shape as one of the reasons why the Green Bank Telescope in West Virginia should listen for radio emissions from it to see if there were any unexpected signs that it might be of artificial origin, although earlier limited observations by other radio telescopes such as the SETI Institute's Allen Telescope Array had produced no such results. On 13 December 2017, the Green Bank Telescope observed the asteroid for six hours. No radio signals from ʻOumuamua have been detected.
On 26 October 2018, Loeb and his postdoctoral student Shmuel Bialy submitted a paper exploring the possibility of the interstellar object ʻOumuamua being an artificial thin solar sail accelerated by solar radiation pressure in an effort to help explain the object's non-gravitational acceleration. Other scientists have stated that the available evidence is insufficient to consider such a premise, and that a tumbling solar sail would not be able to accelerate. In response, Loeb wrote an article detailing six anomalous properties of `Oumuamua that make it unusual, unlike any comets or asteroids seen before.
On 27 November 2018, Loeb and Amir Siraj, an undergraduate student at Harvard College, proposed a search for `Oumuamua-like objects which might be trapped in the Solar System as a result of losing orbital energy through a close encounter with Jupiter. They identified four candidates (2011 SP25, 2017 RR2, 2017 SV13, and 2018 TL6) for trapped interstellar objects which could be visited by dedicated missions. The authors pointed out that future sky surveys, such as with LSST, could find many more.
In public interviews and private communications with reporters and academic colleagues, Loeb has become more and more vocal regarding the prospects of proving the existence of alien life.
On April 16, 2019, Loeb and Siraj reported the discovery of the first meteor of interstellar origin.
Extraterrestrial: The First Sign of Intelligent Life Beyond Earth, a popular science account concerning 'Oumuamua, written by Loeb, was published in 2021.
In 2006, Loeb was featured in a TIME magazine cover story on the first stars, and in a Scientific American article on the Dark Ages of the universe. In 2008, he was featured in a Smithsonian magazine cover story on black holes, and in two Astronomy Magazine cover stories, one on the collision between the Milky Way and the Andromeda Galaxy and the second on the future state of our universe. In 2009, Loeb reviewed in a Scientific American article a new technique for imaging black hole silhouettes. Loeb received considerable media attention after proposing in 2011 (with E.L. Turner) a new technique for detecting artificially-illuminated objects in the Solar System and beyond, and showing in 2012 (with I. Ginsburg) that planets may transit hypervelocity stars or get kicked to a fraction of the speed of light near the black hole at the center of the Milky Way.
Science magazine published an article about Loeb's career in April 2013, and Discover reviewed his research on the first stars in April 2014. The New York Times published a science profile of Loeb in December 2014. In May 2015, Astronomy posted a podcast of an hour-long interview with Loeb in its series entitled "Superstars of Astronomy". In April 2016, Stephen Hawking visited Loeb's home and attended the inaugurations of the Starshot and Black Hole Initiatives that Loeb leads.
Loeb's eBook on Kindle details his career path from childhood on a farm with interests in philosophy to chairing the Harvard Astronomy department and directing the ITC, and includes opinion essays on the importance of taking risks in research and promoting diversity. Loeb writes opinion essays on science and policy.
On January 17, 2021 he appeared on the Joe Rogan Experience podcast #1596.
Following a public dispute with astronomer Jill Tarter during a 2021 webinar presented by the Pontifical Catholic University of Chile, Loeb received criticism for behavior that some characterized as inappropriate and sexist. Loeb subsequently issued an apology to Tarter and colleagues at the Harvard-Smithsonian Center for Astrophysics.
Honors and awards
Loeb has received many honors, including:
- 2015 – Elected Fellow of the International Academy of Astronautics (IAA) SETI Permanent Committee
- 2015 – Elected Member of the American Physical Society (APS)
- 2014 – Member of the Board on Physics & Astronomy (BPA) of the National Academies
- 2013 – Chambliss Astronomical Writing Award from the American Astronomical Society, for the book “How Did the First Stars and Galaxies Form?” (2010)
- 2013 – Miegunyah Distinguished Visiting Fellowship, University of Melbourne, Australia
- 2012 – Elected member of the American Academy of Arts & Sciences
- 2012 – Galileo Galilei Chair (Cattedra Galileiana) Award, Scuola Normale Superiore, Pisa, Italy
- 2011 – Sackler Lecturer in Astronomy, Leiden Observatory, Netherlands
- 2011 – Las Cumbres Observatory Prize Lecturer in Astrophysics, UC Santa Barbara
- 2009 – Distinguished Visiting Scientist at the Carnegie Observatories, Pasadena
- 2007 – Inaugural Australian Institute of Physics (AIP) End of Year Lecturer
- 2007 – Merle Kingsley Distinguished Visitor at the California Institute of Technology (Caltech)
- 2006/7 – John Bahcall Lecturer at Tel Aviv University University
- 2006 – Salpeter Lectureship at Cornell University
- 2004 – Distinguished Visiting Professorship at the Faculty of Physics and the Einstein Center for Theoretical Physics, Weizmann Institute of Science
- 2002 – Guggenheim Fellowship
- 1987 – The Kennedy Prize, Hebrew University of Jerusalem
- "Avi Loeb". Institute for Theory and Computation @ Harvard University. Harvard University.
- "Professor Avi Loeb". Harvard & Smithsonian Center For Astronomy. Harvard University.
- "Abraham (Avi) Loeb". Black Hole Initiative @ Harvard University. Harvard University.
- Loeb, Avi. "Autobiographical sketch" (PDF). Harvard University.
- Loeb, Abraham. "Curriculum Vitae of Abraham Loeb" (PDF). Harvard University.
- "Avi Loeb". Department of Astronomy @ Harvard University. Harvard University.
- "BPA". nationalacademies.org. Retrieved 2016-09-07.
- "PCAST_Swearing_In_Ceremony". cfa.harvard.edu. Retrieved 2020-06-30.
- "PCAST_Members". osti.gov. Retrieved 2020-07-01.
- David Bjerklie. "The 25 Most Influential People in Space" (PDF). cfa.harvard.edu. Retrieved 2016-02-19.
- Groll, Johan (7 January 2019). "Thinking About Distant Civilizations Isn't Speculative". Der Spiegel. Retrieved 7 January 2019.
- Siraj, A. and, Loeb, A. (16 April 2019). "Discovery of a Meteor of Interstellar Origin". arXiv:1904.07224 [astro-ph.EP].
- Carmeli, Oded (2019). "If true, this could be one of the greatest discoveries in human history". Haaretz.com.
- Abraham Loeb (1998). "Direct Measurement of Cosmological Parameters from the Cosmic Deceleration of Extragalactic Objects". The Astrophysical Journal. 499 (2): L111–L114. arXiv:astro-ph/9802122. Bibcode:1998ApJ...499L.111L. doi:10.1086/311375. S2CID 6479300.
- Cox, T. J.; Loeb, Abraham (2008). "The collision between the Milky Way and Andromeda". Monthly Notices of the Royal Astronomical Society. 386 (1): 461–474. arXiv:0705.1170. Bibcode:2008MNRAS.386..461C. doi:10.1111/j.1365-2966.2008.13048.x. S2CID 14964036.
- Loeb, Abraham (2002). "Long-term future of extragalactic astronomy". Physical Review D. 65 (4): 47301. arXiv:astro-ph/0107568. Bibcode:2002PhRvD..65d7301L. doi:10.1103/PhysRevD.65.047301. S2CID 1791226.
- o'Leary, Ryan M.; Loeb, Abraham (2012). "Recoiled star clusters in the Milky Way halo: N-body simulations and a candidate search through the SDSS". Monthly Notices of the Royal Astronomical Society. 421 (4): 2737–2750. arXiv:1102.3695. Bibcode:2012MNRAS.421.2737O. doi:10.1111/j.1365-2966.2011.20078.x. S2CID 118524459.
- Stone, N; Loeb, A (2012). "Observing Lense-Thirring Precession in Tidal Disruption Flares". Physical Review Letters. 108 (6): 61302. arXiv:1109.6660. Bibcode:2012PhRvL.108f1302S. doi:10.1103/PhysRevLett.108.061302. PMID 22401052. S2CID 33103563.
- Broderick, Avery E.; Loeb, Abraham (2006). "Testing General Relativity with High-Resolution Imaging of Sgr A*". Journal of Physics: Conference Series. 54: 448–455. arXiv:astro-ph/0607279. Bibcode:2006JPhCS..54..448B. doi:10.1088/1742-6596/54/1/070. S2CID 16053017.
- "How Did the First Stars and Galaxies Form?" book jacket (pdf)
- Loeb, Abraham (2016-02-08). Loeb, A.: How Did the First Stars and Galaxies Form? (eBook and Paperback). Press.princeton.edu. ISBN 9780691145167. Retrieved 2016-02-19.
- Faigler, S.; Tal-Or, L.; Mazeh, T.; Latham, D. W.; Buchhave, L. A. (1 July 2013). "BEER Analysis of Kepler and CoRoT Light Curves. I. Discovery of Kepler-76b: A Hot Jupiter with Evidence for Superrotation". The Astrophysical Journal. 771 (1): 26. arXiv:1304.6841. Bibcode:2013ApJ...771...26F. doi:10.1088/0004-637X/771/1/26. S2CID 119247392.
- Abraham Loeb; B. Scott Gaudi (2003). "Periodic Flux Variability of Stars due to the Reflex Doppler Effect Induced by Planetary Companions". The Astrophysical Journal. 588 (2): L117–L120. arXiv:astro-ph/0303212. Bibcode:2003ApJ...588L.117L. doi:10.1086/375551. S2CID 10066891.
- Rea, N.; Esposito, P.; Pons, J. A.; Turolla, R.; Torres, D. F.; Israel, G. L.; Possenti, A.; Burgay, M.; Viganò, D.; Papitto, A.; Perna, R.; Stella, L.; Ponti, G.; Baganoff, F. K.; Haggard, D.; Camero-Arranz, A.; Zane, S.; Minter, A.; Mereghetti, S.; Tiengo, A.; Schödel, R.; Feroci, M.; Mignani, R.; Götz, D. (2013). "A Strongly Magnetized Pulsar within the Grasp of the Milky Way's Supermassive Black Hole". The Astrophysical Journal. 775 (2): L34. arXiv:1307.6331. Bibcode:2013ApJ...775L..34R. doi:10.1088/2041-8205/775/2/L34. S2CID 15111955.
- Eric Pfahl; Abraham Loeb (2004). "Probing the Spacetime around Sagittarius A* with Radio Pulsars". The Astrophysical Journal. 615 (1): 253–258. arXiv:astro-ph/0309744. Bibcode:2004ApJ...615..253P. doi:10.1086/423975. S2CID 14470701.
- Palladino, Lauren E.; Schlesinger, Katharine J.; Holley-Bockelmann, Kelly; Allende Prieto, Carlos; Beers, Timothy C.; Lee, Young Sun; Schneider, Donald P. (2014). "Hypervelocity Star Candidates in the SEGUE G and K Dwarf Sample". The Astrophysical Journal. 780 (1): 7. arXiv:1308.3495. Bibcode:2014ApJ...780....7P. doi:10.1088/0004-637X/780/1/7. S2CID 119251211.
- Blake D. Sherwin; Abraham Loeb; Ryan M. O'Leary (2008). "Hypervelocity stars from the Andromeda galaxy". Monthly Notices of the Royal Astronomical Society. 386 (3): 1179–1191. arXiv:0709.1156. Bibcode:2008MNRAS.386.1179S. doi:10.1111/j.1365-2966.2008.13097.x. S2CID 18336240.
- Lemonick, Michael D. (26 November 2014). "You've Heard of Shooting Stars, But This is Ridiculous". Time.
- Howard Chen; John C. Forbes; Abraham Loeb (2018). "Habitable Evaporated Cores and the Occurrence of Panspermia Near the Galactic Center". The Astrophysical Journal Letters. 855 (1): L1. arXiv:1711.06692. Bibcode:2018ApJ...855L...1C. doi:10.3847/2041-8213/aaab46. S2CID 119398803.
- "The Mystery of Dark Matter Clarified—a Little". Time. 5 September 2013.
- "Supernova Shines Light On Black Hole Formation". NPR.org. Retrieved 2016-02-19.
- "Could Tiny Stars Be Home to Mirror Earths?". Time. 6 March 2013.
- ""The First Galaxies in the Universe" by Loeb and Furlanetto". Cfa.harvard.edu. Retrieved 2016-02-19.
- Loeb, Abraham (9 September 2014). "The habitable epoch of the early Universe". International Journal of Astrobiology. 13 (4): 337–339. arXiv:1312.0613. Bibcode:2014IJAsB..13..337L. doi:10.1017/S1473550414000196. S2CID 2777386.
- Adam Frank. "First Life In The Universe : 13.7: Cosmos And Culture". NPR.org. Retrieved 2016-02-19.
- Lemonick, Michael D. (24 July 2014). "The Search for Extraterrestrial Air Pollution". Time.
- Siraj, Amir; Loeb, Abraham (2020-04-17). "Possible Transfer of Life by Earth-Grazing Objects to Exoplanetary Systems". Life. 10 (4): 44. arXiv:2001.02235. doi:10.3390/life10040044. ISSN 2075-1729. PMC 7235815. PMID 32316564.
- Loeb, Avi (2020-11-29). "Noah's Spaceship". Scientific American. Retrieved 2021-02-18.
- Ian Sample (11 December 2017). "Astronomers to check interstellar body for signs of alien technology". The Guardian. Retrieved 12 December 2017.
Green Bank telescope in West Virginia will listen for radio signals from ʻOumuamua, an object from another solar system ... "Most likely it is of natural origin, but because it is so peculiar, we would like to check if it has any sign of artificial origin, such as radio emissions," said Avi Loeb, professor of astronomy at Harvard University and an adviser to the Breakthrough Listen project. "If we do detect a signal that appears artificial in origin, we’ll know immediately." ... While many astronomers believe the object is an interstellar asteroid, its elongated shape is unlike anything seen in the asteroid belt in our own solar system. Early observations of ʻOumuamua show that it is about 400m long but only one tenth as wide. "It's curious that the first object we see from outside the solar system looks like that," said Loeb.
- Billings, Lee (11 December 2017). "Alien Probe or Galactic Driftwood? SETI Tunes In to ʻOumuamua". Scientific American. Retrieved 12 December 2017.
So far limited observations of ‘Oumuamua, using facilities such as the SETI Institute’s Allen Telescope Array, have turned up nothing.
- "Breakthrough Listen Releases Initial Results and Data from Observations of 'Oumuamua". Breakthrough Listen. 13 December 2017. Retrieved 15 December 2017.
No evidence of artificial signals emanating from the object so far detected by the Green Bank Telescope, but monitoring and analysis continue. Initial data are available for public inspection in the Breakthrough Listen archive
- Ian Sample (15 December 2017). "Is 'Oumuamua an alien spacecraft? Initial scans show no signs of technology". The Guardian. Retrieved 15 December 2017.
- Williams, Matt (2 November 2018). "Could Oumuamua Be an Extra-Terrestrial Solar Sail?". Universe Today. Retrieved 2 November 2018.
- Bialy, Shmuel; Loeb, Abraham (26 October 2018). "Could Solar Radiation Pressure Explain 'Oumuamua's Peculiar Acceleration?". The Astrophysical Journal. 868 (1): L1. arXiv:1810.11490. Bibcode:2018ApJ...868L...1B. doi:10.3847/2041-8213/aaeda8. S2CID 118956077.
- Loeb, Abraham (26 September 2018). "How to Search for Dead Cosmic Civilizations". Scientific American. Retrieved 26 September 2018.
- Scientists push back against Harvard 'alien spacecraft' theory. Kerry Sheridan, PhysOrg. 7 November 2018.
- Boyle, Alan (2018-11-06). "'Oumuamua, oh my! Was interstellar object actually an alien solar sail? Not so fast". Yahoo!. Retrieved 2018-11-08.
- Schadwinkel, Alina (2018-11-08). "Glaubt dieser Harvard-Professor selbst, was er sagt?". Zeit Online. Retrieved 2018-11-08.
- Cigar-shaped interstellar object may have been an alien probe, Harvard paper claims. CNN News. 6 November 2018.
- Koren, Marina (23 January 2019). "When a Harvard Professor Talks About Aliens – News about extraterrestrial life sounds better coming from an expert at a high-prestige institution". The Atlantic. Retrieved 23 January 2019.
- Loeb, Abraham (20 November 2018). "6 Strange Facts about the Interstellar Visitor 'Oumuamua". Scientific American. Retrieved 20 November 2018.
- Chotiner, Isaac (16 January 2019). "Have Aliens Found Us? A Harvard Astronomer on the Mysterious Interstellar Object 'Oumuamua". The New Yorker. Retrieved 16 January 2019.
- Siraj, Amir; Loeb, Abraham (27 November 2018). "Identifying Interstellar Objects Trapped in the Solar System through Their Orbital Parameters". arXiv:1811.09632v2 [astro-ph.EP].
- Siraj, Amir; Loeb, Abraham (2019). "Identifying Interstellar Objects Trapped in the Solar System through Their Orbital Parameters". The Astrophysical Journal. 000 (1): L10. arXiv:1811.09632. Bibcode:2019ApJ...872L..10S. doi:10.3847/2041-8213/ab042a. S2CID 119198820.
- Post, The Washington. "Harvard's top astronomer says an alien ship may be among us". nola.com. Archived from the original on 2019-02-05. Retrieved 2019-02-05.
- "Object that whizzed by Earth probably came from alien world, Harvard professor asserts". www.cbsnews.com. Retrieved 2021-01-13.
- Tucker, Reed (2021-01-02). "A Harvard professor says an alien visited in 2017 — and more are coming". New York Post. Retrieved 2021-01-13.
- Anderson, Travis (4 January 2021). "In new book, Harvard astronomer pushes theory about object that passed through solar system; alien world may have sent it – The Boston Globe". BostonGlobe.com. Retrieved 2021-01-13.
- "Breaking News, Analysis, Politics, Blogs, News Photos, Video, Tech Reviews - TIME.com". Time. 10 November 2011.
- Loeb, Abraham; Turner, Edwin L. (April 2012). "Detection Technique for Artificially Illuminated Objects in the Outer Solar System and Beyond". Astrobiology. 12 (4): 290–294. arXiv:1110.6181. Bibcode:2012AsBio..12..290L. doi:10.1089/ast.2011.0758. PMC 3330268. PMID 22490065.
- Ginsburg, Idan; Loeb, Abraham; Wegner, Gary A. (11 June 2012). "Hypervelocity planets and transits around hypervelocity stars". Monthly Notices of the Royal Astronomical Society. 423 (1): 948–954. arXiv:1201.1446. Bibcode:2012MNRAS.423..948G. doi:10.1111/j.1365-2966.2012.20930.x. S2CID 119193699.
- Avi Loeb. "NewsFocus : From Cosmic Dawn to Milkomedia, and beyond" (PDF). Cfa.harvard.edu. Retrieved 2016-02-19.
- Steve Nadis. "First" (PDF). Cfa.harvard.edu. Retrieved 2016-02-19.
- Dreifus, Claudia (2 December 2014). "Much-Discussed Views That Go Way Back – Avi Loeb Ponders the Early Universe, Nature and Life". The New York Times. Retrieved 3 December 2014.
- "Abraham Loeb: From cosmic origins to our galaxy's fate". Astronomy.com. 2015-05-06. Retrieved 2016-02-19.
- "Last Visit of Stephen Hawking to the US in April 2016". cfa.harvard.edu/~loeb/SI.html. 2018-03-16. Retrieved 2018-03-16.
- "From the First Star to Milkomeda, Abraham Loeb, Dror Burstein, Todd Hasak-Lowy, Noa Moav". Amazon.com. Retrieved 2016-02-19.
- "Opinion Essays by Abraham Loeb". cfa.harvard.edu~/loeb/Opinion.html. 2018-03-18. Retrieved 2018-03-18.
- Ethan Siegel (16 February 2021). "Watch: Harvard Astronomer Mansplains SETI To The Legend Who Inspired Carl Sagan's Contact". Forbes.com. Retrieved 16 February 2021.
- "Avi Loeb". John Simon Guggenheim Foundation.