Sudhansu Datta Majumdar: Difference between revisions

{{Use dmy dates|date=September 2014}}

| alma_mater              = [[Presidency College, Calcutta]] (B.Sc.)<br>[[Rajabazar Science College]] (M.Sc.), (Ph.D.), (D.Sc.)

| known_for              = [[General Relativity]], [[Electrodynamics]], [[Spectroscopy]], [[Group Theory]]

Born in 1915 in [[Sylhet]] (now in Bangladesh), Sudhansu Datta Majumdar had his education in [[Sylhet]]; [[Presidency College, Calcutta]], and University College of Science also called [[Rajabazar Science College]], [[Calcutta University]]. In an academic career spanning several decades, he served in different capacities in various institutions. Beginning with a stint in the Palit Laboratory of Physics, [[Rajabazar Science College]], [[Calcutta University]], from where he wrote the now famous Majumdar–Papapetrou paper,<ref name = majumdar>{{cite journal| last = Majumdar| first = S D| title = A Class of Exact Solutions of Einstein's Field Equations | year = 1947| journal = [[Physical Review]]| volume = 72| issue = 5| pages =390–398| doi = 10.1103/PhysRev.72.390 |bibcode = 1947PhRv...72..390M }}</ref> he was appointed Lecturer in Physics in Calcutta University in 1951. Subsequently, he became a reader there in 1960.  During 1956–57, he went to Cambridge University, United Kingdom, on an educational tour to interact with [[P. A. M. Dirac]]. In 1962, Majumdar obtained the rare honour of the degree of D.Sc. in Physics from Sc. College, Calcutta University, one of his thesis examiners being [[J.A. Wheeler]]. Three years later, in 1965, he joined [[IIT, Kharagpur]], as a Professor of Physics where he served till 1975. His last academic appointment was, as a Professor of Mathematics in Visva Bharati, Shantiniketan. In 1974, he was invited by [[Yeshiva University]], New York, to deliver a course of lectures. He visited the Mathematics Department, Monash University, Australia, between July and December 1976. [[Calcutta Mathematical Society]] elected him as their president in 1980. The diverse areas in which he contributed substantially include --- [[general relativity]], [[electrodynamics]], [[group theory]] and [[spectroscopy]]. He died in Calcutta in 1997.<ref name=memorial>{{cite journal| title = Memorial: Sudhansu Datta Majumdar (1915–1997)| journal = [[Ansatz (journal)|Ansatz]]| volume = 3| url = http://www.phy.iitkgp.ernet.in/ansatz3/Memorial.html| url-status = dead| archive-url = https://web.archive.org/web/20110721154906/http://www.phy.iitkgp.ernet.in/ansatz3/Memorial.html| archive-date = 21 July 2011| df = dmy-all}}</ref>

The phenomenon of static equilibrium for a system of point charges is well known in Newtonian theory, where the mutual gravitational and electrostatic forces can be balanced by fine-tuning the charge suitably with the particle masses. The corresponding generalisation, in the form of static solutions of the coupled, source-free Einstein-Maxwell equations, was discovered by Majumdar and Papapetrou independently{{citation needed|date=June 2017}} in 1947.<ref name = majumdarb>{{cite journal| last = Datta Majumdar| first = Sudhansu| title = A Class of Exact Solutions of Einstein's Field Equations | year = 1947 | journal = [[Physical Review]]| volume = 72| issue = 5 | pages =390–398 | doi = 10.1103/PhysRev.72.390|bibcode = 1947PhRv...72..390M }}</ref><ref name = papapetrou>{{cite journal| last = Papapetrou| first = A | journal = [[Proceedings of the Royal Irish Academy, Section A]]| volume = 51| pages =191| year =1947}}</ref> These gravitational fields assume no spatial symmetry and also contain geodesics which are incomplete. While work continued on understanding these solutions better, a renewed interest in this metric was generated by the important observation of [[Werner Israel|Israel]] and Wilson in 1972 that static black-hole spacetimes with the mass being equal to the magnitude of the charge are of Majumdar–Papapetrou form. In the same year, it was shown by [[James Hartle|Hartle]] and [[Stephen Hawking|Hawking]]<ref name = hartle-hawking>{{cite journal|author1=Hartle, James B. |author2=Hawking, Stephen |name-list-style=amp | title = Solutions of the Einstein-Maxwell equations with many black holes| journal = [[Communications in Mathematical Physics]]| volume = 26| issue =2 | pages =87–101| year =1972 |doi=10.1007/BF01645696 |bibcode = 1972CMaPh..26...87H |s2cid=122638569 }}</ref> that these spacetimes can be analytically extended to electrovacuum black hole spacetimes with a regular domain of outer communication. They interpreted this as a system of charged black holes in equilibrium under their gravitational and electrical forces. Each one of these many black holes or the multi-black holes system has a spherical topology and hence is a fairly regular object. In a more recent development, the uniqueness of the metric was discussed by Heusler, Chrusciel and others. These and other aspects of the Majumdar–Papapetrou metric have attracted considerable attention on the classical side, as well as in the work and applications from the perspective of string theory. In particular, the mass equal to charge aspect of these models was used extensively in certain string theoretic considerations connected to black hole entropy and related issues.

where U(x,y,z) can be extended in spatial directions till one encounters a singularity or till U(x,y,z) vanishes.

[[Category:Indian Institute of Technology Kharagpur faculty]]