Research Papers (JVN)
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Item Astronomy at the millennium(2002-03-27) Narlikar, J. V.This paper will highlight the important developments in astronomy in the last decade of the twentieth century and in the opening years of the twenty-first, On the observational front, the discovery of extra-solar planets, the detection of gamma- ray bursts and studies of the distances of extragalactic supernovae with implications for the expansion of the universe are the major developments highlighted here. On the theoretical front, the paper reports on the speculations in very high energy physics that have implications for cosmology, the role of the cosmological constant and the quasi-steady state cosmology proposed as an alternative to the big bang.Item Creation of matter and anomalous redshifts(Kluwer Academic Publishers, 2002-03-26) Narlikar, J. V.This presentation discusses the role of creation of matter in cosmology. While the phenomenon is considered a singular event in the big bang model, a more physical description is given in the quasi-steady state cosmology. Some highlights of this model are presented. Finally, the observations of anomalous redshifts are briefly described and viewed as a consequence of newly created matter ejected from older matter.Item Quasi-steady state cosmology: A problem of stability(American Astronomical Society, 1997-09-20) Banerjee, Shyamal K.; Narlikar, J. V.This paper examines the gravitational stability against small perturbations of the -. This model was first introduced by Hoyle et al., who in subsequent papers looked at its various theoretical and observational implications. Here we carry out a perturbation analysis of the exact solution of the field equations obtained by Sachs et al. in the noncreative mode which describes the oscillatory feature of this model. We show that the perturbations grow only to a limited amount and then fall o†, thus confirming the stability of the solution. We discuss the implications of this result for structure formation in this cosmologyItem Astro-particle physics in the quasi-steady state cosmology(Hadronic Press, 1997-06-25) Narlikar, J. V.This work highlights the conceptual and theoretical issues underlying the quasi- steady state cosmology which was proposed by the F. Hoyle, G. Burbidge and the author as an alternative to the standard big band cosmology. In particular, it is argued that this cosmology offers the high energy particle physicists several challenging problems on the cosmology-panicle physics frontier. To begin with it is shown with the help of a toy model how the problems of spacetime singularity and violation of the energy momentum conservation law that are present in the standard cosmology can be avoided by introducing a scalar field minimally coupled to gravity and having its sources in events where matter is created. It is then shown that matter creation preferentially occurs near collapsed massive objects and the scalar field created at such mini-creation events has a feedback on spacetime geometry causing the universe to have a steady expansion as in the de Sitter model but with periodic phases of expansion and contraction superposed on it. The parameters of the toy model can be empirically fixed in relation to the cosmological observations thus providing tests of the theory. Next it is argued that the toy model arises from a deeper theory which is Machian in origin with the inertia of a particle determined by the rest of the particles in the universe in a long range conformally invariant scalar interaction. The characteristic mass of a particle created is then the Planck mass. The Planck particle decays quickly to baryons. It is shown that the inertial effects produced by the Planck particles during their brief existence generate the scalar field of the toy model while the inertial effects of the stable baryonic particles give the more familiar Einstein equations of relativity. The baryons into which the Planck particle decays from an SU3 octet which, in the high density - high energy environment of mini-creation event finally forms the nuclei of hydrogen, heliu m and other elements of low atomic masses. These predicted abundances match those actually found. Finally it is shown that extending the theory to the most general confor- mally invariant form automatically leads to the cosmological constant whose sign and magnitude are of the right cosmological order.Item Quasi-steady state cosmology: some recent developments(Indian Academy of Sciences, 1997-03-13) Narlikar, J. V.This paper summarises the recent work on the quasi-steady state cosmology. This includes, the theoretical formulation and simple exact solutions 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.Item Alternative cosmologies(Kluwer, Dordrecht, 1997-11-14) Narlikar, J. V.Item Quasi-steady state cosmology(Dordrecht, Reidel, 1995-03-29) Hoyle, F.; Burbidge, G.; Narlikar, J. V.Item Problems of astro-particle physics in the quasi-steady state cosmology(World Scientific Publishing Company, 1995-03-16) Narlikar, J. V.