Abraham (Avi) Loeb 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 serves as Chair of the Harvard Astronomy department (since 2011), Chair of the Advisory Committee for the Breakthrough Starshot project – which aims to launch lightweight spacecraft towards the nearest stars using a powerful laser (since 2016), founding director of Harvard's Black Hole Initiative – the first interdisciplinary center worldwide dedicated to the study of black holes  (since 2016), and director of the Institute for Theory and Computation (ITC) (since 2007) within the Harvard-Smithsonian Center for Astrophysics. Loeb is an elected fellow of the American Academy of Arts and Sciences, the American Physical Society, and the International Academy of Astronautics. As of July 2018, he was appointed as chair of the Board on Physics and Astronomy (BPA) of the National Academies, which is the Academies' principal forum for issues connected with the fields of Physics and Astronomy including oversight of their decadal surveys. 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.
Loeb was born in Israel in 1962 and took part in the national Talpiot program before receiving a graduate degree in plasma physics at age 24 from the Hebrew University in Jerusalem. 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 received many honors, including the Kennedy prize in 1987, the Guggenheim Fellowship in 2002, the Salpeter Lectureship at Cornell University in 2006, the Bahcall Lectureship at Tel Aviv University in 2006, the Merle Kingsley Lectureship at Caltech in 2007, the Australian Institute of Physics Lectureship at the University of Melbourne in 2007, the Distinguished Visiting Lectureship at the Carnegie Observatories in 2009, the Las Cumbres Observatory Lectureship at Santa Barbara in 2011, the Sackler Lectureship at Leiden Observatory in 2011, the Galileo Galilei Chair ("Cattedra Galileiana") for 2011–12 from Scuola Normale Superiore in Pisa, Italy, and the Miegunyah Distinguished Visiting Fellowship for 2013 at the University of Melbourne in Australia. For over two decades he held a visiting professorship at the Weizmann Institute of Science, and since 2011 he was awarded a Sackler Professorship by special appointment in the School of Physics and Astronomy at Tel Aviv University. In 2012 Loeb was elected as a member of the American Academy of Arts and Sciences. In 2013, he was awarded the Chambliss Astronomical Writing Award by the American Astronomical Society for the book he published in 2010.
Loeb has published more than six hundred 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. Some of his papers (e.g., on planet microlensing, and 21-cm cosmology) are considered as pioneering in areas that have become by now the focus of established communities of astrophysicists. Loeb was among the very first theorists to trigger the research frontier on the "cosmic dawn" of the first stars and galaxies. In a series of papers with his students and postdocs, he addressed how and when the first stars and black holes formed and what effects they had on the young universe. He also led a team that discovered tentative evidence for the birth of a black hole in the young nearby supernova SN1979C.
In 2006, Loeb was featured in a cover story of TIME magazine on the first stars and in a Scientific American article on the Dark Ages of the universe. In 2008, he was featured in a cover story of Smithsonian magazine on black holes and in two cover stories of Astronomy Magazine, 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. In 2010 he wrote a textbook entitled "How Did the First Stars and Galaxies Form?", published by Princeton University Press. In the same year, Loeb wrote an article encouraging young researchers to be creative. 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.
Several of Loeb's early predictions were confirmed in recent years. 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, SgrA*, 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 former student Steve Furlanetto (currently a professor at UCLA), Loeb published in December 2012 an extensive textbook entitled "The First Galaxies in the Universe". 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) over the next decade in the atmosphere of Earth-mass planets in the habitable zone of white dwarfs. Together with Paolo Pani, Loeb showed in 2013 that primordial black holes in the range between the masses of the Moon and the Sun cannot make up the dark matter, another result reported in TIME magazine. 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. 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*.
Science magazine published a detailed article about Loeb's career in April 2013, and Discover magazine reviewed his pioneering 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 magazine 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 latest 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 regularly writes timely opinion essays on science and policy.
- "Department of Astronomy". Astronomy.fas.harvard.edu. Retrieved 2016-02-19.
- "Breakthrough Starshot". breakthroughinitiatives.org/Leaders/3/. Retrieved 2016-04-12.
- "Black Hole Initiative". bhi.fas.harvard.edu/. Retrieved 2016-04-21.
- "Institute for Theory and Computation - Harvard-Smithsonian Center for Astrophysics". cfa.harvard.edu. Retrieved 2016-02-19.
- "BPA". nationalacademies.org. Retrieved 2016-09-07.
- David Bjerklie. "The 25 Most Influential People in Space" (PDF). cfa.harvard.edu. Retrieved 2016-02-19.
- Abraham Loeb (1998). "DIRECT MEASUREMENT OF COSMOLOGICAL PARAMETERS FROM THE COSMIC DECELERATION OF EXTRAGALACTIC OBJECTS" (PDF). The Astrophysical Journal. 499: L111/L114. arXiv: . Bibcode:1998ApJ...499L.111L. doi:10.1086/311375. Retrieved 2016-02-19.
- "The collision between the Milky Way and Andromeda". Monthly Notices of the Royal Astronomical Society. 386: 461–474. 2008. arXiv: . Bibcode:2008MNRAS.386..461C. doi:10.1111/j.1365-2966.2008.13048.x.
- "Long-term future of extragalactic astronomy". Physical Review D. 65: 47301. 2002. arXiv: . Bibcode:2002PhRvD..65d7301L. doi:10.1103/PhysRevD.65.047301.
- "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: 2737–2750. 2012. arXiv: . Bibcode:2012MNRAS.421.2737O. doi:10.1111/j.1365-2966.2011.20078.x.
- Stone, N; Loeb, A (2012). "Observing Lense-Thirring Precession in Tidal Disruption Flares". Physical Review Letters. 108: 61302. arXiv: . Bibcode:2012PhRvL.108f1302S. doi:10.1103/PhysRevLett.108.061302. PMID 22401052.
- "Testing General Relativity with High-Resolution Imaging of Sgr A*". Journal of Physics Conference Series. 54: 448–455. 2006. arXiv: . Bibcode:2006JPhCS..54..448B. doi:10.1088/1742-6596/54/1/070.
- "Discovering planetary systems through gravitational microlenses". The Astrophysical Journal. 396: 104. 1992. Bibcode:1992ApJ...396..104G. doi:10.1086/171700.
- "Expected Number and Flux Distribution of Gamma‐Ray Burst Afterglows with High Redshifts". The Astrophysical Journal. 540: 687–696. arXiv: . Bibcode:2000ApJ...540..687C. doi:10.1086/309384.
- Loeb, Abraham; Zaldarriaga, Matias (25 May 2004). "Measuring the Small-Scale Power Spectrum of Cosmic Density Fluctuations through 21 cm Tomography Prior to the Epoch of Structure Formation". Physical Review Letters. 92 (21): 211301. arXiv: . Bibcode:2004PhRvL..92u1301L. doi:10.1103/PhysRevLett.92.211301. PMID 15245272.
- "Supernova Shines Light On Black Hole Formation". NPR.org. Retrieved 2016-02-19.
- "How Did the First Stars and Galaxies Form?" book jacket (pdf)
- "Loeb, A.: How Did the First Stars and Galaxies Form? (eBook and Paperback)". Press.princeton.edu. 2016-02-08. Retrieved 2016-02-19.
- Abraham Loeb (2010-08-09). "Taking "The Road Not Taken": On the Benefits of Diversifying Your Academic Portfolio". arXiv: [astro-ph.IM].
- "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: . Bibcode:2012AsBio..12..290L. doi:10.1089/ast.2011.0758.
- 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: . Bibcode:2012MNRAS.423..948G. doi:10.1111/j.1365-2966.2012.20930.x.
- 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: . Bibcode:2013ApJ...771...26F. doi:10.1088/0004-637X/771/1/26.
- Abraham Loeb; B. Scott Gaudi (2003). "PERIODIC FLUX VARIABILITY OF STARS DUE TO THE REFLEX DOPPLER EFFECT INDUCED BY PLANETRY COMPANIONS" (PDF). The Astrophysical Journal. 588: L117–L120. arXiv: . Bibcode:2003ApJ...588L.117L. doi:10.1086/375551. Retrieved 2016-02-19.
- "A Strongly Magnetized Pulsar within the Grasp of the Milky Way's Supermassive Black Hole". The Astrophysical Journal. 775: L34. 2013. arXiv: . Bibcode:2013ApJ...775L..34R. doi:10.1088/2041-8205/775/2/L34.
- Eric Pfahl; Abraham Loeb (2004). "PROBING THE SPACETIME AROUND SAGITTARIUS A* WITH RADIO PULSARS" (PDF). The Astrophysical Journal. 615: 253–258. arXiv: . Bibcode:2004ApJ...615..253P. doi:10.1086/423975. Retrieved 2016-02-19.
- "Hypervelocity Star Candidates in the SEGUE G and K Dwarf Sample". The Astrophysical Journal. 780: 7. 2014. arXiv: . Bibcode:2014ApJ...780....7P. doi:10.1088/0004-637X/780/1/7.
- Blake D. Sherwin; Abraham Loeb; Ryan M. O'Leary (2008). "Hypervelocity stars from the Andromeda galaxy". Monthly Notices of the Royal Astronomical Society. 386: 1179–1191. arXiv: . Bibcode:2008MNRAS.386.1179S. doi:10.111/j.1365-2966.2008.13097.x.
- ""The First Galaxies in the Universe" by Loeb and Furlanetto". Cfa.harvard.edu. Retrieved 2016-02-19.
- "Could Tiny Stars Be Home to Mirror Earths?". Time. 6 March 2013.
- "The Mystery of Dark Matter Clarified—a Little". Time. 5 September 2013.
- Loeb, Abraham (9 September 2014). "The habitable epoch of the early Universe". International Journal of Astrobiology. 13 (04): 337–339. arXiv: . Bibcode:2014IJAsB..13..337L. doi:10.1017/S1473550414000196.
- 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.
- 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" (PDF). The Astrophysical Journal Letters. 855: L1. arXiv: . Bibcode:2018ApJ...855L...1C. doi:10.3847/2041-8213/aaab46. Retrieved 2018-03-01.
- 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.
- Avi Loeb's home page
- Loeb's recent preprints
- Loeb's published papers
- "Scientific American article on "Portrait of a Black Hole"" (PDF). (393 KB)
- "Scientific American article on "The Dark Ages of the Universe"" (PDF). (393 KB)
- "ASTRONOMY magazine article on "The State of the Universe"" (PDF). (5.72 MB)
- "Smithsonian Magazine cover story on "Homing In on Black Holes"" (PDF). (2.65 MB)
- "ASTRONOMY Magazine cover story on "Milkomeda"" (PDF). (853 KB)
- "TIME Magazine cover story, entitled: "Let There Be Light"" (PDF). (51.5 MB)
- Future Collision of the Milky Way and Andromeda
- An introductory movie to Loeb's book