Thanu Padmanabhan (born 10 March 1957) is an Indian theoretical physicist and cosmologist whose research spans a wide variety of topics in Gravitation, Structure formation in the universe and Quantum Gravity. He has published more than 260 papers and reviews in international journals and ten books in these areas. He has had many contributions related to the analysis and modelling of dark energy in the universe and the interpretation of gravity as an emergent phenomenon. He is currently a Distinguished Professor at the Inter-University Centre for Astronomy and Astrophysics, (IUCAA) at Pune, India.
Born in 1957, Padmanabhan did his schooling in Thiruvananthapuram and earned his B.Sc. (1977) and M.Sc. (1979) in Physics, from the University College, Kerala University. He published his first research paper (on general relativity) when he was still a B.Sc. student, at the age of 20. He joined the Tata Institute of Fundamental Research (TIFR), Mumbai in 1979 for his Ph.D. and became a faculty member there in 1980. He held various faculty positions at TIFR during 1980-1992 and also spent a year (in 1986-87) at the Institute of Astronomy, Cambridge. He moved to IUCAA in 1992 and served as its Dean, Core Academic Programmes, for 18 years (1997-2015).
Padmanabhan has also served as Adjunct Faculty of the Tata Institute of Fundamental Research (Mumbai), the Harish-Chandra Research Institute (Allahabad), the Raman Research Institute (Bangalore) and the Indian Institute of Science, Education and Research (IISER, Pune) at different periods in his career. He is currently adjunct faculty of IISER, Mohali.
He was the elected President of the Cosmology Commission (2009-2012) of the International Astronomical Union (IAU) and Chairman of the Astrophysics Commission (2011-2014) of the International Union of Pure and Applied Physics (IUPAP). He has also been a Visiting Faculty at many institutes including the California Institute of Technology, Princeton University, and a Sackler Distinguished Astronomer of the Institute of Astronomy, Cambridge. He is also an elected fellow of TWAS and the three National Academies of Science in India.
He is married to Vasanthi Padmanabhan, who has a Ph.D. in astrophysics from TIFR, Mumbai and has one daughter, Hamsa Padmanabhan, who has a Ph.D. in astrophysics from IUCAA, Pune.
Padmanabhan has received several national and international awards including:
Padmanabhan's work in the last decade, interpreting gravity as an emergent phenomenon, has far-reaching implications both for quantum gravity and for the nature of dark energy. He provided a clear interpretation of gravity as an emergent phenomenon and showed that this paradigm extends to a wide class of theories of gravitation including, but not limited to, general relativity. Padmanabhan could also show that several peculiar aspects of classical gravitational theories find natural interpretations in this approach. This approach also provides a novel solution to the cosmological constant problem. He has given two lectures at the Oxford-Cambridge collaborative conference on "Cosmology and the Constants of Nature" about this.
Popular descriptions of his work have been published in Scientific American (India), and a more technical description is available in an article from the Gravity Research Foundation in 2008, that describes his First Prize work. Another popular article about his work which appeared in a German science magazine along with the English translation is available in his home page. Also available is an interview of Padmanabhan by George Musser about his work.
Padmanabhan's early work was in quantum cosmology, structure formation in the universe and statistical mechanics of gravitating systems. In the 1980s, he provided an interpretation of the Planck length as the `zero-point length' of the spacetime based on very general considerations. This result, established by theoretical considerations and well-chosen thought experiments, finds an echo in more recent results in several other candidate models for quantum gravity. He has made significant contributions to the study of statistical mechanics of gravitating systems and was a pioneer in the systematic application of these concepts to study the gravitational clustering in an expanding universe.
Padmanabhan has authored several advanced level textbooks which are acclaimed as magnificent achievements and used worldwide as standard references.