Research Papers (JVN)

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3C 273 : A gravitationally lensed quasar?
(EDP Sciences, 1984-05-30) Chitre, S. M.; Narasimha, D.; Narlikar, J. V.; et al.
It is suggested that the abnormal brightness of the quasar 3C 273, coupled with the observations of superluminal motions in its radio core B as well as the misalignment of its VLBI jet with the optical jet, can be understood by postulating a faint spheroidal lensing galaxy located about halfway along the line of sight to the quasar. The lens model also helps to understand why the quasar is found slightly off-centre with respect to its nebulosity. The probability for such a lens system to arise for 3C 273 by chance is shown to be no less than that computed on the basis of the relativistic beaming hypothesis. Further tests of the lens model are discussed.
Absorber theory of radiation in expanding universe
(Kluwer Academic Publishers, 2002-10-28) Narlikar, J. V.
The Wheeler-Feynman absorber theory of radiation of the symmetric combination of retarded and advanced potentials, originally developed in a static universe model, is applied to asymptotic boundary conditions for an action-at-a-distance electro dynamic framework of a Quasi-Steady State Universe; which as discussed is in opposition to the broad class of Big bang cosmologies.
Absorber theory of radiation in expanding universes
(Astronomical Society of India, 1995-04-14) Narlikar, J. V.
Academy fellowship problem
(Indian Academy of Sciences, 1995-12-25) Narlikar, J. V.
Action and reaction in the theories of direct interparticle action
(Elsevier Science Publishers, 1975-08-12) Narlikar, J. V.
Newton’s third law of motion is examined in the context of the theories of direct interparticle action. In such theories, interactions between particles travel backward and forward in time at speeds not exceeding the speed of light. It is shown that while in the flat spacetime the equality of action and reaction can be clearly demonstrated, the situation is considerably more complicated in the curved spacetime. The phenomenon of gravitational scattering intervenes to destroy the equality of action and reaction. Nevertheless, when gravitation is taken into account, there is no violation of the con- servation law of energy and momentum. These results are discussed in the framework of general relativity for the case of the electromagnetic interaction.
Action at a distance and cosmology : A historical perspective
(Annual Reviews Inc., 2003-06-04) Narlikar, J. V.
The first law of theoretical physics, the Newtonian law of gravitation, relies on the concept of action at a distance. The success of this law led to the concept being applied to electricity and magnetism, which were next to be explored in depth. Here the action at a distance had a limited success and ultimately had to be abandoned in favor of the increasingly more popular field theory. Nevertheless, in the 1940s, an attempt was made to revive the concept of action at a distance in a relativistically in-variant way by Wheeler & Feynman (1945, 1949). It inspired a series of investigations in both electrodynamics and gravity in which the field concept was not used but the interaction was described as taking place directly between particles. As it impinged very intimately on cosmology, Hoyle was keenly interested in it. This review discusses the work by Hoyle, the author, and others on the development of electrodynamics and gravitation as direct particle theories. In this review, the author discusses how the work was started and went through stages of increasing sophistication, e.g., extending the Wheeler-Feynman electrodynamics to curved spacetime, its consequences in different cosmologies, and the issues arising from its quantization. The resolution of ultraviolet divergences in quantum electrodynamics is also briefly discussed. The parallel development of a Machian theory of gravitation followed the lead from electrodynamics. In both theories one sees a strong link between the large-scale structure of the universe and local physics, as might be expected from an action-at-a-distance framework.
Action at a distance in electrodynamics and inertia
(Nova Science Publishers, 2001-03-14) Narlikar, J. V.
This paper reviews the parallel development of electrodynamics and gravitation as direct particle theories, echoing the ideals of Ernst Mach. It is shown that a synthesisj of Mach's ideas with these two interactions leads to their better conceptual understanding, Both interactions, however, show that the resulting framework is relativistically invariant and thus precludes instantaneous action at a distance. At the same time, they establish a strong link between the large scale structure of the universe and local phys.cs, as might be expected from an action at a distance framework.
Alternative cosmologies
(Dordrecht, D. Reidel Publishing Co., 1987-04-12) Narlikar, J. V.
This review highlights some of the cosmological theories proposed as alternatives to the standard hot big bang model. Specific ideas discussed here are the matter-antimatter symmetric cosmologies, the empirical two-component model, the G-varying cosmologies, the chronometric cosmology and a simplified quantum cosmology. It is argued that many alternative cosmologies have contributed useful concepts and offered observational tests that have enriched the field of cosmology as a science.
Alternative cosmologies
(AIP Conference Proccedings, 2009-02-02) Narlikar, J. V.
Alternative cosmologies
(Kluwer, Dordrecht, 1997-11-14) Narlikar, J. V.
Alternative cosmology
(Korean Astronomical Society, 1996-06-18) Narlikar, J. V.
Recent discussions of observational constraints on the standard hot big bang model are reviewed and it is argued that now there is room for considering alternative cosmologies. The quasi-steady state cosmology is briefly described. This model seems to explain most of the observed features of the universe, including the m-z relation, radio source count, the light nuclear abundances and the microwave background.
Alternative cosmology
(P.C. Vaidya Sanman Nidhi Trust, 1993-03-29) Narlikar, J. V.
Alternative cosmology: The QSSC
(International Astronomical Union, 1999-03-24) Narlikar, J. V.
This review begins with a brief survey of the observational constraints on the standard big bang cosmology, pointing out that the various limits leave a very narrow window in the parameter space of plausible models. There is thus a strong case for alternative cosmologies. The rest of the review concentrates on one alternative, the quasi steady state cosmology (QSSC) and summaries the recent work on this model. The includes the theoretical formulation and simple exact solution of the basic equations, their relationship to observations, the stability of solutions and the toy model for understanding the growth of structures in the universe.
Alternative ideas in cosmology
(Cambridge University Press, 2005-03-30) Narlikar, J. V.
It is shown that in cosmology, as in the rest of science, the evaluation of observational evidence and theoretical concepts has often led to the acceptance of ideas that were once considered outlandish. Fred Hoyle himself was responsible for generating several such ideas, although he was much ahead of his time. Here some of those ideas are outlined, ideas that were thought to be unrealistic at the time they were proposed, but which we have now been assimilated into mainstream cosmology. A general comment that emerges from such examples is that highly creative individuals who are far ahead of their time do not get the recognition they deserve once their ideas are accepted as standard.
Alternative to big bang cosmology
(World Scientiﬁc Publishing Company, 1995-03-15) Narlikar, J. V.
Amal Kumar Raychaudhuri
(Indian National Science Academy, 2006-01-09) Narlikar, J. V.
Angular appearance of white holes
(Springer, 1978-01-22) Narlikar, J. V.; Kapoor, R. C.
It is shown that non-radial light rays emitted from the surface of a white hole can emerge from inside the Schwarzschild barrier. The upper limit on their impact parameter is calculated under the requirement that such rays are blueshifted. The apparent angular size of the white hole determined by blueshifted rays is shown to grow so rapidly in the early stages of its expansion that it produces the appearance of superluminal expansion.
Anomalous redshifts and the variable mass hypothesis
(Korean Astronomical Society, 1997-05-18) Narlikar, J. V.
There are several observations of extragalactic objects that do not appear to be consistent with the cosmological hypothesis that their redshifts arise from the expansion of the universe. These phenomena are looked at in a spacetime framework that is wider in its scope than general relativity. This framework directly incorporates the Machian notion of intertia and is conformally invariant. The consequence of this approach is that the mass of a particle may not stay constant. Two alternative viewpoints are presented to explain how large redshifts could arise from emission of radiation by particles of low masses.
Anomalous redshifts of QSOs
(Reidel, 1980-01-01) Narlikar, J. V.; Das, P. K.
Anomalous redshifts of quasi-stellar objects
(American Astronomical Society, 1980-09-01) Narlikar, J. V.; Das, P. K.
This paper is based on the assumption that the observational evidence to date does point to the possibility that high-redshift quasars are physically associated with low-redshift galaxies. It is first argued that the excess (or anomalous) redshifts of the quasars in such associations are unlikely to be either of Doppler or of gravitational origin. A new source for this excess redshift was suggested by Narlikar on the basis of the Hoyle-Narlikar theory of gravitation which is based on Mach's principle. This idea is applied to the hypothesis that quasars may have been ejected from galactic nuclei. The dynamics of such an ejection and its observable consequences are discussed. In particular, it is shown that quasar alignments and redshift bunching which have been observed recently can be understood within the framework of this theory. Further tests of this hypothesis are discussed.