>Abhishek Sengupta 24 at 06:08, 21 June 2021

2021-06-21T06:08:39Z

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{{EngvarB|date=June 2015}}
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{{Infobox scientist
| name = Amal Kumar Raychaudhuri
| image = [[File:AKRaychaudhuri.jpg|220px|Amal Kumar Raychaudhuri at IUCAA, Pune, in 1991]]
| birth_date = 14 September 1923
| death_date = {{d-da|18 June 2005|14 September 1923}}
| birth_place = [[Barisal]], [[East Bengal]], [[British India]] (now [[Bangladesh]])
| death_place =
| other_names = AKR<ref name="auto">{{cite journal|url=https://www.researchgate.net/publication/250673075|title=The legacy of Amal Kumar Raychaudhuri|first=Parongama|last=Sen|date=1 April 2008|journal=Resonance|volume=13|issue=4|pages=308–309|access-date=2 January 2018|via=ResearchGate|doi=10.1007/s12045-008-0011-3|s2cid=122069175|url-status=live|archive-url=https://web.archive.org/web/20180102142954/https://www.researchgate.net/publication/250673075_The_legacy_of_Amal_Kumar_Raychaudhuri|archive-date=2 January 2018}}</ref>
| nationality = [[India]]n
| field = [[Theoretical physics]]
| work_institution = [[Asutosh College]]<ref>{{cite web|url=http://www.telegraphindia.com/1050627/asp/knowhow/story_4907454.asp|website=The Telegraph |title=Calcutta : KnowHOW |access-date=2 January 2018 |url-status=live|archive-url=https://web.archive.org/web/20160304140550/http://www.telegraphindia.com/1050627/asp/knowhow/story_4907454.asp|archive-date=4 March 2016}}</ref> <br> [[Indian Association for the Cultivation of Science]]<br>[[Presidency College, Kolkata]]
| education = [[Presidency College, Kolkata|Presidency College (B.Sc.)]] <br>[[Rajabazar Science College | Science College]] (M.Sc.)
| doctoral_advisor =
| doctoral_students =
| notable_students = [[Ashoke Sen]]<ref>{{Cite web|url=https://presiuniv.ac.in/web/history_physics.php|title=Presidency University|website=presiuniv.ac.in|access-date=19 September 2019}}</ref> <br> [[Narayan Chandra Rana]]
| known_for = [[Raychaudhuri equation]]
| prizes =
| signature = Amal Kumar Raychaudhuri signature.svg
| footnotes =
| spouse = Nomita Sen<ref name="auto"/>
| children = 3<ref>{{cite web |url=http://www.insaindia.res.in/BM/BM30_0608.pdf |title=Amal Kumar Raychaudhuri |work=insaindia.res.in|access-date=1 January 2018 |url-status=live |archive-url=https://web.archive.org/web/20170706193034/http://insaindia.res.in/BM/BM30_0608.pdf |archive-date=6 July 2017 }}</ref>
}}

'''Amal Kumar Raychaudhuri''' (14 September 1923 – 18 June 2005) was an [[Indian people|Indian]] [[physicist]], known for his research in [[general relativity]] and [[cosmology]]. His most significant contribution is the eponymous [[Raychaudhuri equation]], which demonstrates that singularities arise inevitably in general relativity and is a key ingredient in the proofs of the [[Penrose–Hawking singularity theorems]].<ref name=:0>{{cite web|url=http://www.thehindu.com/sci-tech/science/no-big-bang-the-universe-was-there-all-along-studies/article6959499.ece|title=No Big Bang, the universe was there all along: studies|first=Shubashree|last=Desikan|date=5 March 2015|access-date=2 January 2018|via=www.thehindu.com|url-status=live|archive-url=https://web.archive.org/web/20170621211441/http://www.thehindu.com/sci-tech/science/no-big-bang-the-universe-was-there-all-along-studies/article6959499.ece|archive-date=21 June 2017}}</ref> Raychaudhuri was also revered as a teacher during his tenure at [[Presidency College, Kolkata|Presidency College]], Kolkata.<ref>{{cite web|url=https://www.news18.com/news/india/amal-kumar-raychaudhuri-the-bengal-connection-to-penroses-physics-nobel-for-black-hole-discoveries-2945741.html|title=Amal Kumar Raychaudhuri: The Bengal Connection to Penrose's Physics Nobel for Black Hole Discoveries}}</ref>

==Career==
Raychaudhuri was born in a [[Baidya]]<ref>{{Cite web|date=2020-10-09|title=Amal Kumar Raychaudhuri: The Bengal Connection to Penrose's Physics Nobel for Black Hole Discoveries|url=https://www.news18.com/news/india/amal-kumar-raychaudhuri-the-bengal-connection-to-penroses-physics-nobel-for-black-hole-discoveries-2945741.html|access-date=2021-06-21|website=www.news18.com|language=en}}</ref> family coming from [[Barisal]] (now in [[Bangladesh]]) on 14 September 1923, to Surabala and Sureshchandra Raychaudhuri. He was just a child when the family migrated to Kolkata. He had his early education in [[Tirthapati Institution]] and later completed matriculation from [[Hindu School, Kolkata]]. In a documentary film made just before his death in 2005, AKR reveals that he was extremely passionate about mathematics right from his schooldays and solving problems would give him immense pleasure. May be the fact that his father was a mathematics teacher in a school also inspired him. At the same time, as his father was not so 'successful' so to say, he was discouraged to take up mathematics, his first choice, as honours subject in college.<ref>{{Cite journal|last=Sen|first=Parongama|date=1 April 2008|title=The legacy of Amal Kumar Raychaudhuri|url=https://www.researchgate.net/publication/250673075|journal=Resonance|volume=13|issue=4|pages=308–309|doi=10.1007/s12045-008-0011-3|s2cid=122069175|url-status=live|archive-url=https://web.archive.org/web/20180102142954/https://www.researchgate.net/publication/250673075_The_legacy_of_Amal_Kumar_Raychaudhuri|archive-date=2 January 2018}}</ref>

He earned B.Sc. from the Presidency College in 1942 and M.Sc. in 1944 from [[Rajabazar Science College | Science College]] campus of [[Calcutta University]] and he joined Indian Association for the Cultivation of Science (IACS) in 1945 as a research scholar. In 1952, he took a research job with the [[Indian Association for the Cultivation of Science]] (IACS), but to his frustration was required to work on the properties of metals rather than general relativity. Despite these adverse pressures, he was able to derive and publish the equation which is now named for him a few years later. [[Raychaudhuri equation]] is a key ingredient in the proofs of the [[Penrose–Hawking singularity theorems]].<ref name=:0/>

Some years later, having learned that his 1955 paper was highly regarded by notable physicists, such as [[Pascual Jordan]], Raychaudhuri was sufficiently emboldened to submit a doctoral dissertation, and received his Doctor of Science degree at the University of Calcutta (with one of the examiners, [[John Archibald Wheeler|Prof John Archibald Wheeler]] recording special appreciation of the work done) in 1959.

In 1961, Raychaudhuri joined the faculty of his alma mater, [[Presidency College, Kolkata|Presidency College]] then affiliated with the [[University of Calcutta]], and remained there until his superannuation. He became a well-known scientific figure in the 1970s, and was the subject of a short documentary film completed shortly before his death.<ref>"[https://www.youtube.com/watch?v=i9_hm2qe34s Documentary on Amal Kumar Raychaudhuri, the renowned theoretical physicist from Kolkata"] {{webarchive|url=https://web.archive.org/web/20160307021440/https://www.youtube.com/watch?v=i9_hm2qe34s |date=7 March 2016 }}</ref>

Dipayan Pal wrote of Raychaudhuri for Science Reporter (CSIR, NISCAIR) in 2018:<ref>{{Cite journal|last=Pal|first=Dipayan|date=2018|title=For the Pursuit of Excellence – Contribution of Prof. Amal Kumar Raychaudhuri in the field of Astrophysics|url=http://nopr.niscair.res.in/handle/123456789/45371|journal=Science Reporter|volume=55|pages=36–37|via=NISCAIR}}</ref> <blockquote>In general relativity, the Raychaudhuri equation plays a significant role to explain the space-time singularities and gravitational focusing properties in cosmology. He aimed to address the fundamental question of singularity in the most simple and general form with no reference to any symmetry and any specific property of space-time and energy distribution.

The first mention of the term ‘Raychaudhuri Equation’ appeared in a research paper published in 1965 by George F.R. Ellis and Stephen Hawking. The Raychaudhuri equation<ref>{{cite journal|url=https://link.springer.com/content/pdf/10.1007/s12043-007-0106-5.pdf|title=A. K. Raychaudhuri and his equation ~Springer|doi=10.1007/s12043-007-0106-5|hdl=11858/00-001M-0000-0013-4825-8|s2cid=120398395|hdl-access=free}}</ref> hit the zenith of fame as it was a key tool in the hands of young relativists like Stephen Hawking and Roger Penrose in the middle of the late 1960s in their attempt to answer the question on the existence of space-time singularities and to explain the theory of universe. In fact, this equation is important as a fundamental lemma for the Penrose-Hawking singularity theorems.

There is such wide acceptability of this equation like other notable equations in physics like ‘the Dirac equation and Schroedinger equation’ that nobody cares about its origin or date of publication. The Raychaudhuri equation paved the way for later research into the singularity problem. It would find its place in venerable textbooks on general relativity and relativistic cosmology. The equation will stand firm so long Einstein’s GTR stands. The equation remains a prime tool to investigate the behaviour of black hole horizons. One would wonder if there is any research work of such grade to have emerged in post-independent India.</blockquote>

== Honours and recognition ==
* He was elected member of the International Committee on General Relativity and Gravitation for the period 1974–83.
* During 1980–82, he was President of the [https://www.imsc.res.in/~iagrg/ Indian Association of General Relativity and Gravitation]<ref name="auto1">{{Cite web|url=http://www.insaindia.res.in/BM/BM30_0608.pdf|title=Amal Kumar Raychaudhuri |work=insaindia.res.in/BM/BM30_0608.pdf|archive-url=https://web.archive.org/web/20170706193034/http://insaindia.res.in/BM/BM30_0608.pdf|archive-date=6 July 2017|url-status=live}}</ref>
* He was elected Fellow of the [[Indian Academy of Sciences]] in 1982.<ref>{{Cite web|url=http://www.ias.ac.in/listing/fellows/deceased|title=Fellowship {{!}} Indian Academy of Sciences|website=www.ias.ac.in|language=en|access-date=1 January 2018|url-status=live|archive-url=https://web.archive.org/web/20170818164756/http://www.ias.ac.in/listing/fellows/deceased|archive-date=18 August 2017}}</ref>
* [[University Grants Commission (India)|UGC]] Emeritus Fellow from 1986 to 1988.
* He was elected Fellow of the [[Indian National Science Academy]] in 1987.<ref name="auto2">{{Cite web|url=http://www.insaindia.res.in/detail/N87-0976|title=INSA :: Deceased Fellow Detail|website=www.insaindia.res.in|access-date=1 January 2018|url-status=live|archive-url=https://web.archive.org/web/20180102142955/http://www.insaindia.res.in/detail/N87-0976|archive-date=2 January 2018}}</ref>
* Fellow of the [[National Academy of Sciences, India|National Academy of Sciences]].<ref>{{Cite web|url=http://iacs.res.in/fellow-insa.html|title=Fellow of the INSA (FNA)|website=iacs.res.in|language=en|access-date=1 January 2018|url-status=live|archive-url=https://web.archive.org/web/20170628105503/http://iacs.res.in/fellow-insa.html|archive-date=28 June 2017}}</ref>
* Honorary Fellow of the Astrophysical Society of India<ref name="auto2" />
* Awarded Professor A.C. Banerji Memorial Lecture Award (1989) by National Academy of Sciences.<ref>{{Cite web|url=http://www.nasi.org.in/leca.htm|website=The National Academy of Sciences, India |title=Awardee |access-date=1 January 2018|url-status=live|archive-url=https://web.archive.org/web/20150413015954/http://www.nasi.org.in/leca.htm|archive-date=13 April 2015}}</ref>
* Honorary Fellow of [[Inter-University Centre for Astronomy and Astrophysics|Inter-University Centre of Astronomy and Astrophysics, Pune]].<ref name="auto2" />
* He was [[Indian National Science Academy]] Senior Scientist (1988–91).
* He was conferred Vainu Bappu Memorial Award (1991) by [[Indian National Science Academy]].<ref>{{Cite web|url=http://www.insaindia.res.in/recipients.php|title=INSA :: Awards Recipients|website=www.insaindia.res.in|access-date=1 January 2018|url-status=live|archive-url=https://web.archive.org/web/20170910083544/http://insaindia.res.in/recipients.php|archive-date=10 September 2017}}</ref>
* [[Honorary degree|Honoris causa]] from [[University of Burdwan|Burdwan University]], [[University of Kalyani|Kalyani University]] and [[Vidyasagar University]].<ref name="auto1" />
* Honorary Visiting Professor, [[Jadavpur University]], Kolkata.

==Notes==
{{Reflist}}

==References==
*{{citation|last=Dadhich|first= Naresh|title= Amal Kumar Raychaudhuri (1923–2005) |journal= Current Science|volume= 89|year=2005|pages=569–570 | url=http://www.ias.ac.in/currsci/aug102005/569.pdf }}
*{{citation|last=Narlikar|first=J. V.|title=Amal Kumar Raychaudhuri|journal=Biographical Memoirs of Fellows of the Indian National Science Academy|pages=169|url=http://www.insaindia.res.in/BM/BM30_0608.pdf|date=January 2006|access-date=4 July 2013}}
*{{citation|last=Sen|first=Parongama|title= The Legacy of Amal Kumar Raychaudhuri|journal=Biographical Memoirs of Fellows of the Indian National Science Academy|date=April 2008|pages=309 | url=http://www.ias.ac.in/article/fulltext/reso/013/04/0308-0309}}
*Interview with Professor Amal Kumar Raychaudhuri (2003), [https://www.youtube.com/watch?v=TyJYfUr80hs Part 1] & [https://www.youtube.com/watch?v=BPyA8B7RNTM Part 2]
*[http://www.insaindia.res.in/BM/BM30_0608.pdf Biography at insaindia.res.in]

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{{DEFAULTSORT:Raychaudhuri, Amal Kumar}}
[[Category:1923 births]]
[[Category:2005 deaths]]
[[Category:People from Barisal]]
[[Category:Hindu School, Kolkata alumni]]
[[Category:Presidency University, Kolkata alumni]]
[[Category:University of Calcutta alumni]]
[[Category:People from Barisal District]]
[[Category:Bengali physicists]]
[[Category:20th-century Indian physicists]]
[[Category:Presidency University, Kolkata faculty]]
[[Category:University of Calcutta faculty]]

Amal Kumar Raychaudhuri - Revision history

>Abhishek Sengupta 24 at 06:08, 21 June 2021