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Thanu Padmanabhan

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For the writer, seeT. Padmanabhan.

Thanu Padmanabhan
Born10 March 1957[1]
Trivandrum,Kerala,India
Died17 September 2021(2021-09-17)(aged 64)
Pune,Maharashtra,India
Alma mater•Kerala University,
•Tata Institute of Fundamental Research
Awards•Shanti Swarup Bhatnagar Award(1996)
•Padma Shri(2007)
•Infosys Science Foundation Prize(2009)
Scientific career
FieldsPhysics,astronomy
InstitutionsInter-University Centre for Astronomy and Astrophysics[1]
Doctoral advisorJayant Narlikar

Thanu Padmanabhan(10 March 1957 – 17 September 2021) was an Indiantheoretical physicistandcosmologistwhose research spanned a wide variety of topics ingravitation,structure formationin theuniverseandquantum gravity.He published nearly 300 papers and reviews in international journals and ten books in these areas. He made several contributions related to the analysis and modelling ofdark energyin the universe and the interpretation of gravity as anemergent phenomenon.He was a Distinguished Professor at theInter-University Centre for Astronomy and Astrophysics(IUCAA) atPune,India.[2]

Life and career[edit]

Born to Thanu Iyer and Lakshmi on 10 March 1957 inThiruvananthapuram(then Trivandrum), Padmanabhan attended school there. He earned hisB.Sc.(1977) andM.Sc.(1979) inPhysicsfrom theUniversity College Thiruvananthapuram,part ofKerala University.[1]He published his first research paper (ongeneral relativity) when he was still a B.Sc. student, at the age of 20.[3]He joined theTata Institute of Fundamental Research(TIFR) inMumbaiin 1979 for hisPh.D.and became a faculty member there in 1980.[1]He held various faculty positions at TIFR from 1980 to 1992 and also spent a year (in 1986–87) at theInstitute of Astronomy, Cambridge.He moved to Pune to work at theInter-University Centre for Astronomy and Astrophysicsin 1992 and served as its Dean, Core Academic Programmes, for 18 years (1997–2015).[4]

Padmanabhan served as adjunct faculty of TIFR, theHarish-Chandra Research Institute(Allahabad), theRaman Research Institute(Bangalore) and theIndian Institute of Science, Education and Research(IISER, Pune) at different periods in his career. He was adjunct faculty of IISER,Mohali.[5]

Padmanabhan served as chairman (2006–09) of the Time Allocation Committee[6]of the Giant Meterwave Radio Telescope of NCRA. He was chairman (2008–11) of the Indian National Science Academy's National Committee[7]which interfaces with the activities of the International Astronomical Union. In addition to advising the Government on policy issues, this also required him to coordinate the International Year of Astronomy 2009 activities in the country.[5]

He was elected president of the Cosmology Commission (2009–2012) of theInternational Astronomical Union(IAU) and provided advice to IAU activities in this field. He was elected in 2011 as chairman of the Astrophysics Commission (2011–2014) of theInternational Union of Pure and Applied Physics(IUPAP)[8]and co-ordinated the activities of IUPAP in this area. He was also a visiting faculty at many institutes including theCalifornia Institute of Technology,Princeton University,and a Sackler Distinguished Astronomer of theInstitute of Astronomy, Cambridge.He was an elected fellow ofThe World Academy of Sciencesand of all three National Academies of Science in India (theIndian National Science Academy,Indian Academy of Sciences,and theNational Academy of Sciences, India).[5]

In addition to his scientific research, Padmanabhan worked actively to popularize science and gave over 300 popular science lectures and authored more than 100 popular science articles. He did a comic strip serialThe Story of Physics[9]aimed at school children. Published by Vigyan Prasar (New Delhi), it was translated into half a dozen regional Indian languages and made available at an affordable price at Indian schools. To commemorate the International Year of Astronomy (IYA) in 2009, he published (withJ. V. Narlikarand Samir Dhurde) the IYA Astronomical Diary 2009,[10]which comprises 53 illustrated pages of astronomical information. In 2019, he co-authored with Vasanthi PadmanabhanThe Dawn of Science(published by Springer[11]).

He was married to Vasanthi Padmanabhan, who has a Ph.D. in astrophysics from TIFR, Mumbai, and they had one daughter, Hamsa Padmanabhan, who herself has a Ph.D. in astrophysics from IUCAA, Pune.[12]

He died on 17 September 2021 at the age of 64 after a heart attack at his residence in Pune.[4][13]A tribute article written by his former graduate students and post-doctoral fellows and physics friends from college days has been posted on the Physics arXiv.[14]

Key awards and distinctions[edit]

Padmanabhan received several national and international awards including:[15]

His research work won prizes nine times (in 1984, 2002, 2003, 2006, 2008, 2012, 2014, 2018 and 2020) including the First Prize in 2008 from theGravity Research Foundation,USA.[28]

A Stanford study in 2020, listing top scientists in different fields, ranked Padmanabhan as 24th in the world in his research area.[29][30]

Research[edit]

Padmanabhan's research was on the fields of gravitation and cosmology which includesquantum gravityand nature ofdark energy.[31][32]During 2002–2015, he provided a clear interpretation ofgravityas an emergent phenomenon (like elasticity or fluid dynamics) and showed that this paradigm extends to a wide class of theories of gravitation including, but not limited to, general relativity.[33][34]Padmanabhan could show that several peculiar aspects of classical gravitational theories find natural interpretations in this approach.[35]Such an interpretation also provides a novel solution to the cosmological constant problem.[36]He gave two lectures at the Oxford–Cambridge collaborative conference on "Cosmology and the Constants of Nature" about this.[37][38]

Popular (non-technical) descriptions of Padmanabhan's research have been published inScientific American(India),[39]and a more technical description is available in an article from theGravity Research Foundationin 2008, that describes his First Prize work.Another popular articleabout his work which appeared in a German science magazine along with theEnglish translationis available on his home page. An interview of Padmanabhan by George Musser about his work can be foundhere.

In the earlier part of Padmanabhan's career (1980–2001), he made important contributions toquantum cosmology,structure formationin the universe and statistical mechanics of gravitating systems. In the 1980s, he came up with an interpretation of thePlanck lengthas the 'zero-point length' of thespacetimebased on very general considerations.[40]This result, established by theoretical considerations and well-chosen thought experiments,[41]finds an echo in more recent results in several other candidate models forquantum gravity.He developed the complex path method (in 1998[42]) to studyblack hole thermodynamicswhich was a precursor to the 'tunneling paradigm' that became quite popular later on. He was a recognized authority in the subject of the statistical mechanics of gravitating systems[43]and was a pioneer in the systematic application of these concepts to study thegravitational clusteringin anexpanding universe.[44]He was invited to lecture twice at the Les Houches Schools (in 2002 and 2008) to a broader community about this subject.

In November 2016, Padmanabhan published research studies advocating a newparadigm shiftin understandinggravity.[45][46]A key question in quantum gravity lies in understanding the primordial, pre-geometric phase of the universe, from which the classical, geometric phase described by Einstein's equations emerges along with the notions of space and time themselves. Padmanabhan introduced the notion of Cosmic Information (called 'CosmIn'), which allows these two phases to be connected in a fascinating manner. CosmIn, which is aconserved quantity,measures the total information transferred from the quantum gravitational phase to the classical phase of the universe. Quantum gravitational considerations advocate an astonishingly simple value for CosmIn: 4π, the number of information 'bits' on the surface of a sphere of unit radius. Using these considerations, CosmIn was able to relate the numerical value of thecosmological constant– possibly the deepest unsolved problem intheoretical physicstoday – to the energy scale at which the universe made the quantum-to-classical transition.[47]This is the first time that a model with no adjustable parameters is able to provide a holistic explanation for both these observations, which has far-reaching implications for the quantum structure of spacetime. A non-technical account covering this latest development in Padmanabhan's research was published in the magazineNautilus.[48]

Publications[edit]

Books authored[edit]

Padmanabhan authored several advanced level textbooks. In addition, he authored several popular-level science books.

Selected technical review articles[edit]

Selected popular science articles[edit]

References[edit]

  1. ^abcd"Homepage of Padmanabhan".www.iucaa.in.Archivedfrom the original on 24 October 2020.Retrieved19 September2020.
  2. ^"IUCAA - People".IUCAA.Archivedfrom the original on 11 January 2020.Retrieved8 September2019.
  3. ^Padmanabhan, T. (October 1977)."T.Padmanabhan, Solutions of scalar and electromagnetic wave equations in the field of gravitational and electromagnetic waves, Pramana, (1977), 9, 371".Pramana.9(4): 371–384.doi:10.1007/BF02846243.S2CID123557221.Archivedfrom the original on 3 June 2018.Retrieved2 December2020.
  4. ^ab"Renowned astrophysicist Thanu Padmanabhan passes away".The Hindu.17 September 2021.ISSN0971-751X.Archivedfrom the original on 8 October 2021.Retrieved17 September2021.
  5. ^abc"Prof. Padmanabhan: A Personal and Professional History"(PDF).Archived(PDF)from the original on 8 October 2021.Retrieved19 September2021.
  6. ^"GMRT Time Allocation Committee".Archivedfrom the original on 2 February 2020.Retrieved17 January2020.
  7. ^"INSA".Archivedfrom the original on 15 January 2020.Retrieved17 January2020.
  8. ^"Members & Liaisons | IUPAP: The International Union of Pure and Applied Physics".Archivedfrom the original on 24 January 2020.Retrieved17 January2020.
  9. ^"The Story of Physics".Archivedfrom the original on 17 September 2021.Retrieved17 September2021.
  10. ^"IYA Diary: 2009".www.iucaa.ernet.in.Archived fromthe originalon 5 December 2012.Retrieved13 January2022.
  11. ^Padmanabhan, Thanu; Padmanabhan, Vasanthi (2019).The Dawn of Science.doi:10.1007/978-3-030-17509-2.ISBN978-3-030-17508-5.S2CID167177582.Archivedfrom the original on 20 November 2020.Retrieved17 January2020.
  12. ^"Scientific community in Kerala mourns Thanu Padmanabhan's demise | Kochi News".The Times of India.18 September 2021.Archivedfrom the original on 19 September 2021.Retrieved19 September2021.
  13. ^"Theoretical physicist Thanu Padmanabhan passes away in Pune".The Indian Express.17 September 2021.Archivedfrom the original on 17 September 2021.Retrieved17 September2021.
  14. ^Bagla, Jasjeet Singh; Bhattacharya, Krishnakanta; Chakraborty, Sumanta; Engineer, Sunu; Faraoni, Valerio; Kolekar, Sanved; Kothawala, Dawood; Lochan, Kinjalk; Modak, Sujoy; Nair, V. Parameswaran; Paranjape, Aseem (7 October 2021). "The Life and Science of Thanu Padmanabhan".arXiv:2110.03208[physics.hist-ph].
  15. ^"padmanabhan_cv.dvi"(PDF).Archived(PDF)from the original on 9 October 2018.Retrieved17 September2021.
  16. ^"Kerala's prestigious science honor for M S Swaminathan and Thanu Padmanabhan".The Times of India.17 August 2021.Archivedfrom the original on 27 August 2021.Retrieved17 September2021.
  17. ^"Physics scientist Thanu Padmanabhan receives M P Birla Memorial Award in cosmology".30 September 2019.Archivedfrom the original on 17 October 2019.Retrieved17 January2020.
  18. ^"Indian Physics Association".Archivedfrom the original on 27 January 2020.Retrieved17 January2020.
  19. ^"Announcement of TWAS Prize in Physics (2011)".21 November 2011.Archivedfrom the original on 10 November 2015.Retrieved4 February2016.
  20. ^"List of Laureates – Infosys Prize 2009".Archivedfrom the original on 15 March 2016.Retrieved4 February2016.
  21. ^"J.C. Bose Fellowship".Science and Engineering Research Board.2021.Archivedfrom the original on 28 September 2021.Retrieved29 September2021.
  22. ^Khanna, Monnit (17 September 2021)."World-Renowned Physicist Prof Thanu Padmanabhan Dies From Heart Attack At 64".India Times.Archivedfrom the original on 20 September 2021.Retrieved29 September2021.
  23. ^"Recipients".INSA India.Archived from the original on 4 April 2014.{{cite web}}:CS1 maint: unfit URL (link)
  24. ^"Padma Awards"(PDF).Ministry of Home Affairs, Government of India. 2015.Archived(PDF)from the original on 15 October 2015.Retrieved21 July2015.
  25. ^"Shanti Swarup Bhatnagar Prize: Profile of the Awardee".Archivedfrom the original on 8 October 2021.Retrieved4 February2016.
  26. ^"List of B. M. Birla Science Prizes".Archived fromthe originalon 28 January 2018.Retrieved4 February2016.
  27. ^"List of recipients of INSA medal for young scientists 1974-2014".Archivedfrom the original on 11 October 2013.Retrieved4 February2016.
  28. ^"Gravity: An Emergent Perspective".Archivedfrom the original on 7 April 2012.Retrieved9 July2012.
  29. ^Ioannidis, John P. A.; Boyack, Kevin W.; Baas, Jeroen (2020)."Updated science-wide author databases of standardized citation indicators".PLOS Biology.18(10): e3000918.doi:10.1371/journal.pbio.3000918.PMC7567353.PMID33064726.
  30. ^"Explained: Why Stanford University has a list of the top 2 per cent scientists".The Indian Express.19 November 2020.Archivedfrom the original on 1 December 2020.Retrieved2 December2020.
  31. ^Padmanabhan, T. (July 2003)."Cosmological constant—the weight of the vacuum".Physics Reports.380(5–6): 235–320.arXiv:hep-th/0212290.Bibcode:2003PhR...380..235P.doi:10.1016/S0370-1573(03)00120-0.S2CID119440437.Archivedfrom the original on 27 May 2020.Retrieved18 September2021.
  32. ^Padmanabhan, T. (January 2020)."Gravity and quantum theory: Domains of conflict and contact".International Journal of Modern Physics D.29(1): 2030001–2030745.arXiv:1909.02015.Bibcode:2020IJMPD..2930001P.doi:10.1142/S0218271820300013.ISSN0218-2718.S2CID202537535.
  33. ^Padmanabhan, T. (2010). "Thermodynamical aspects of gravity: New insights".Reports on Progress in Physics.73(4): 046901.arXiv:0911.5004.Bibcode:2010RPPh...73d6901P.doi:10.1088/0034-4885/73/4/046901.S2CID209835245.
  34. ^Padmanabhan, T. (2014). "General relativity from a thermodynamic perspective".General Relativity and Gravitation.46(3): 1673.arXiv:1312.3253.Bibcode:2014GReGr..46.1673P.doi:10.1007/s10714-014-1673-7.S2CID119177380.
  35. ^Padmanabhan, Thanu (2011). "Lessons from classical gravity about the quantum structure of spacetime".Journal of Physics: Conference Series.306(1): 012001.arXiv:1012.4476.Bibcode:2011JPhCS.306a2001P.doi:10.1088/1742-6596/306/1/012001.S2CID119249958.
  36. ^Padmanabhan, T.; Padmanabhan, Hamsa (2014). "Cosmological Constant from the Emergent Gravity Perspective".International Journal of Modern Physics D.23(6): 1430011–1430458.arXiv:1404.2284.Bibcode:2014IJMPD..2330011P.doi:10.1142/S0218271814300110.S2CID119181469.
  37. ^"Video: Cosmological constants – Part 1 (Thanu Padmanabhan)".YouTube.Archivedfrom the original on 25 April 2020.Retrieved27 January2016.
  38. ^"Video: Cosmological constants – Part 2 (Thanu Padmanabhan)".YouTube.Archivedfrom the original on 23 April 2020.Retrieved27 January2016.
  39. ^Article:Scientific American(India)
  40. ^Padmanabhan, T. (November 1985)."Physical significance of planck length".Annals of Physics.165(1): 38–58.Bibcode:1985AnPhy.165...38P.doi:10.1016/S0003-4916(85)80004-X.Archivedfrom the original on 18 September 2021.Retrieved18 September2021.
  41. ^Padmanabhan, T. (1987). "Limitations on the operational definition of spacetime events and quantum gravity".Classical and Quantum Gravity.4(4): L107–L113.Bibcode:1987CQGra...4L.107P.doi:10.1088/0264-9381/4/4/007.S2CID250887977.
  42. ^Srinivasan, K.; Padmanabhan, T. (1999). "Particle production and complex path analysis".Physical Review D.60(2): 024007.arXiv:gr-qc/9812028.Bibcode:1999PhRvD..60b4007S.doi:10.1103/PhysRevD.60.024007.S2CID53450120.
  43. ^Padmanabhan, T. (April 1990)."Statistical mechanics of gravitating systems".Physics Reports.188(5): 285–362.Bibcode:1990PhR...188..285P.doi:10.1016/0370-1573(90)90051-3.Archivedfrom the original on 8 October 2021.Retrieved18 September2021.
  44. ^Padmanabhan, Thanu (2002). "Statistical Mechanics of Gravitating Systems in Static and Cosmological Backgrounds".Dynamics and Thermodynamics of Systems with Long-Range Interactions.Lecture Notes in Physics. Vol. 602. pp. 165–207.arXiv:astro-ph/0206131.doi:10.1007/3-540-45835-2_7.ISBN978-3-540-44315-5.
  45. ^Padmanabhan, Thanu(2017). "Do We really Understand the Cosmos?".Comptes Rendus Physique.18(3–4): 275–291.arXiv:1611.03505.Bibcode:2017CRPhy..18..275P.doi:10.1016/j.crhy.2017.02.001.S2CID119214901.
  46. ^Staff (15 November 2016)."Research shows paradigm shift in understanding of gravity".The Indian Express.Archivedfrom the original on 20 November 2016.Retrieved19 November2016.
  47. ^Padmanabhan, T.; Padmanabhan, Hamsa (10 October 2017)."Cosmic information, the cosmological constant and the amplitude of primordial perturbations".Physics Letters B.773:81–85.arXiv:1703.06144.Bibcode:2017PhLB..773...81P.doi:10.1016/j.physletb.2017.07.066.S2CID118886523.Archivedfrom the original on 17 September 2021.Retrieved17 January2020.
  48. ^"The Universe Began with a Big Melt, Not a Big Bang".5 October 2017.Archivedfrom the original on 21 January 2020.Retrieved17 January2020.

External links[edit]

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