Research Papers (JVN)

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Subject: search.filters.subject.Cosmology

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Now showing 1 - 10 of 94
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    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.
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    Mach’s principle
    (2011-04-10) Narlikar, J. V.
    The underlying idea in Mach's principle is that the origin of inertia or mass of a particle is a dynamical quantity determined by the environment, in particular the rest of the matter in the universe. In this article, we discuss the role of this idea in the Brans {Dicke theory of gravitation and the Hoyle {Narlikar cosmology.
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    Cosmology and the origin of nuclei
    (2010-04-06) Narlikar, J. V.
    The problem of explaining the origin of all the chemical elements found in the universe is a central problem in astrophysics. In the 1940s Fred Hoyle suggested that they were cooked inside stars, starting with nucleosynthesis of neutrons and protons. In the same decade George Gamow argued that in a hot big bang universe in the first few minutes, the ambient conditions were suitable for formation of nuclei. This paper will review the progress of both these ideas and show that a reasonable compromise between these ideas can be found today.
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    Fred Hoyle’s universe
    (Indian Academy of Sciences, 2010-10-25) Narlikar, J. V.
    This article recalls some of the seminal contributions to astronomy made by Fred Hoyle. His ideas were thought to be unrealistic at the time they were proposed, but have now been assimilated into mainstream science. A general comment that emerges from such examples is that highly creative individuals who are far ahead of their times do not get the recognition they deserve once their ideas are rediscovered and accepted as standard: for, by the time this hap-pens, they and their contributions are forgotten.
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    Einstein and cosmology
    (Oxford University Press, 2010-04-14) Narlikar, J. V.
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    Alternative cosmologies
    (AIP Conference Proccedings, 2009-02-02) Narlikar, J. V.
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    Cosmological redshift
    (Indian Association of Physics Teachers, 2008-10-29) Narlikar, J. V.
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    Why can’t cosmology be more open?
    (Nature Publishing Group, 2008-01-16) Narlikar, J. V.
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    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.
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    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.