Research Papers (JVN)
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Item 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.Item Alternative cosmologies(AIP Conference Proccedings, 2009-02-02) Narlikar, J. V.Item Cosmological redshift(Indian Association of Physics Teachers, 2008-10-29) Narlikar, J. V.Item Why can’t cosmology be more open?(Nature Publishing Group, 2008-01-16) Narlikar, J. V.Item Cosmology and cosmogony in a cyclic universe(Indian Academy of Sciences, 2007-04-26) Narlikar, J. V.; Burbidge, G.; Vishwakarma, R. G.In this paper we discuss the properties of the quasi-steady state cosmological model (QSSC) developed in 1993 in its role as a cyclic model of the universe driven by a negative energy scalar field. We discuss the origin of such a scalar field in the primary creation process first described by F. Hoyle & J. V. Narlikar forty years ago. It is shown that the creation processes which take place in the nuclei of galaxies are closely linked to the high energy and explosive phenomena, which are commonly observed in galaxies at all redshifts. The cyclic nature of the universe provides a natural link between the places of origin of the microwave background radiation (arising in hydrogen burning in stars), and the origin of the lightest nuclei (H, D, He³ and He⁴). It also allows us to relate the large scale cyclic properties of the universe to events taking place in the nuclei of galaxies. Observational evidence shows that ejection of matter and energy from these centers in the form of compact objects, gas and relativistic particles is responsible for the population of quasi-stellar objects (QSOs) and gamma-ray burst sources in the universe. In the later parts of the paper we briefly discuss the major unsolved problems of this integrated cosmological and cosmogonical scheme – the understanding of the origin of the intrinsic redshifts, and the periodicities in the redshift distribution of the QSOs.Item Einstein’s legacy : Relativistic cosmology(World Scientific, 2007-07-21) Narlikar, J. V.This review gives a historical account of how cosmology has developed since the 1917 paper of Albert Einstein. Current frontier level science draws on contemporary astronomy as well as contemporary physics, stretching both as far as extrapolations will permit. Thanks to numerous observations at different wavelengths, cosmologists today have their plates full. Extrapolations of laboratory tested physics are required for to understand all information within the framework of a standard model. The success and shortcomings of this approach are briefly discussed against the historical backdrop.Item Einstein’s legacy: Relativistic cosmology(Indian Academy of Sciences, 2005-12-25) Narlikar, J. V.This review gives a historical account of how cosmology has developed since the 1917 paper of Albert Einstein. Today it is a frontier level science drawing on contempo-rary astronomy as well as contemporary physics, stretching both as far as extrapolations will permit. Thanks to numerous observations at different wave-lengths, cosmologists today have their plates full. Ex-trapolations of laboratory tested physics are called for to understand all information within the framework of a standard model. The success and shortcomings of this approach are briefly discussed against the historical backdrop.Item 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.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 Baryon non-conservation and Cosmology(Tata McGraw Hill, 1986-12-14) Narlikar, J. V.