Research Publications

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Author: search.filters.author.Narlikar, J. V.Subject: search.filters.subject.Universe

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Now showing 1 - 10 of 30
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    La cosmologia quantistica e l’origine dell’universo
    (2015-04-10) Narlikar, J. V.
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    Are we alone in the universe
    (The Hindustan Times, 1985-09-03) Narlikar, J. V.
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    Life in the universe
    (Indian merchant 's chamber, 1985-07-02) Narlikar, J. V.
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    Exploding Universe
    (Weekly od india, 1983-04-02) Narlikar, J. V.
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    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.
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    Interpretations of the accelerating universe
    (Astronomical Society of the Pacific, 2002-10-26) Narlikar, J. V.; Vishwakarma, R. G.; Burbidge, G.
    It is generally argued that the present cosmological observations support the accelerating models of the universe, as driven by the cosmological constant or `dark energy'. We argue here that an alternative model of the universe is possible which explains the current observations of the universe. We demonstrate this with a reinterpretation of the magnitude-redshift relation for Type Ia supernovae, since this was the test that gave a spurt to the current trend in favour of the cosmological constant.
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    Did the universe have an origin?
    (Indian Journal of Physics, 1985-11-29) Narlikar, J. V.
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    Quantum cosmology and the early universe
    (Italian Physical Society, 1985-11-15) Narlikar, J. V.
    The classical Friedmann cosmology is known to suffer from three major conceptual problems :' (i) spacetime singularity; (ii) particle horizons and (iii) flatness. It is shown that these problems may be resolved during the quantum era of the early universe. Recent attempts in this direction based on the quantization of the conformal degrees of freedom are reviewed here.
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    Counter images in closed elliptical friedmann universes
    (American Astronomical Society, 1985-01-06) Narlikar, J. V.; Seshadri, T. R.
    It is shown that the different connectivity implied by the elliptical version of a closed Friedmann model allows two images of a distant astronomical object to be seen, provided the deceleration parameter q0 of the Friedmann model exceeds unity. Of the two images the direct image is along the shortest-route light track. If the redshift of the direct image exceeds (1.5q0 - 1)/(q0 - 1)sq then a second counterimage should be visible at the diametrically antipodal position. The direct image has a maximum possible redshift, and it is suggested that the apparent cutoff in the redshifts of QSOs may be due to this effect. Other observable consequences of this result are discussed in relation to galaxies and QSOs.
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    Quantum cosmology as a cure of three ailments of classical cosmology
    (Astronomical Society of India, 1983-08-12) Padmanabhan, T.; Narlikar, J. V.
    The standard big bang models of classical cosmology are known to possess three defects. The oldest known defect is spacetime singularity whose existence seems inevitable within the classical framework. The second defect is the existence of a particle horizon which severely limits communications across the distant parts of the universe whose observed homogeneity therefore becomes inexplicable. Recently a third defect has been highlighted, viz., the required fine tuning of the early universe close to the flat spatial model in order to account for the present range of its mean density. We show before that the injection of quantum ideas holds out hope of a cure for all the three ailments described above. Using a simple path integral formalism for quantum cosmology we present arguments which suggest that (i) it is extremely unlikely that the universe evolved to the present state from quantum states of singularity and particles horizon;(ii) of all the possible Robertson-Walker models that could evolve our of quantum fluctuations of the empty Minkowski universe the flat model is overwhelmingly probable.