Dr. Abhay Ashtekar
Penn State University, PA
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Dr. Abhay Ashtekar (b. July 5, 1949, Maharasthara, India) is the Evan Pugh Professor of Physics and holder of the Eberly Chair at The Pennsylvania State University, and of a Distinguished Visiting Chair at the Perimeter Institute, Canada. As the Founding Director, he led the Institute for Gravitation and the Cosmos from 1993 to 2021. Dr. Ashtekar received his PhD in Physics from the University of Chicago in 1974 and won the First Gravity Prize in 1977. He was an Alfred P. Sloan Fellow, and won the Senior Forschungspreis by the Alexander von Humboldt Foundation. He held the Krammers Visiting Chair in Theoretical Physics at the University of Utrecht, Netherlands; and the Sir C. V. Raman Chair of the Indian Academy of Science. He is a fellow of both the American Association for Advancement of Science and the American Physical Society, and is one of only 51 honorary fellows of the Indian Academy of Sciences drawn from the international community. He was awarded Doctor Rerum Naturalium Honoris Causa by the Friedrich-Schiller Universit at Jena, Germany in 2005 and by the Université de Aix-Marseille II, France in 2010. He is a former president of the International Society for General Relativity and Gravitation and a former Chair of what is now the Gravitation Division of the American Physical Society. Ashtekar is a member of the US National Academy of Sciences and a winner of the Einstein Prize of the American Physical Society, given biannually for outstanding contributions to gravitational science.
Ashtekar's scientific work focuses on theoretical aspects of general relativity, cosmology and quantum gravity. He is best known for initiating and developing the Loop Quantum Gravity program by introducing new variables to simplify Einstein's equations; for analyzing the very early universe using Loop Quantum Cosmology. His contributions to the study of the asymptotic structure of space-time and gravitational waves in full non-linear general relativity, has drawn much attention in recent years both because of the discovery of gravitational waves, and because of the revival of interest in their interplay with deep conceptual issues in quantum physics. Ashtekar's group developed the theory of quantum Riemannian geometry that lies at the foundation of Loop Quantum Gravity. It describes `atoms of geometry'. Space-time can be visualized as a fabric that is woven by one-dimensional quantum threads. Thanks to this specific microscopic description, the big bang of general relativity is tamed and replaced by a big bounce. Consequently, there are no infinities and one can study the very early universe unambiguously. This theory has been developed in detail, shown to make predictions that are borne out by the cosmic microwave background missions, and has also made predictions for future observations. It brings out an unforeseen relation between the very small and the very large. Ashtekar and his team have also analyzed global problems in general relativity associated with black holes. They developed the notion of `quasi-local horizons' that is widely used in numerical simulations of black hole collisions, as well as in the investigations of the quantum mechanical evaporation of black holes. On another front, they have shown that the presence of a positive cosmological constant introduces unforeseen issues in the theory of gravitational waves and constructed a framework to address them. In broad terms, these diverse projects explore the interface of physics and geometry.
Dr. Ashtekar had a strong record of outreach. His research has been widely reported in semi-popular media, sometimes as cover stories. These include Nature, Science, The Economist, US News and World Report, New Scientist, Fox News, MSNBC, Spektrum, Bild der Wissenschaft, Geo, La Recherche, Volksprant as well as Australian, Asian and South American press. The New York Times published a feature article on him and his research. He also featured prominently in the German documentary Kosmos prepared in 2008 for the celebration of Max Planck's 150th birthday; in a 2013 Youtube 43 minute long video Before the Big Bang: Loop Quantum Cosmology Explained based on research carried out his group; the 2019 75 minutes long video The story of Loop Quantum Gravity: From the Big Bounce to Black Holes, and the 2019 shorter video Big Bang's New Meaning in which he appears with Stephen Hawking, Roger Penrose and others. Together these videos have well over 500,000 views.
Dr. Ashtekar has served as Editor in Chief of the General Relativity Centennial volume commissioned by the International Society on General Relativity and Gravitation, and also of several international journals in the field. He is on the editorial board of Scholarpedia. He chairs the International Advisory Committee of the Indigo Consortium in connection with the LIGO-India initiative.
For more information, see this webpage.