Research Papers (JVN)

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End date: 1989Subject: search.filters.subject.Cosmology

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Now showing 1 - 10 of 56
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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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    Baryon non-conservation and Cosmology
    (Tata McGraw Hill, 1986-12-14) Narlikar, J. V.
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    Volume of a tetrahedron
    (International Journal of Mathematical Education, 1985-09-29) Narlikar, J. V.
    The area of a triangle can be expressed algebraically in terms of its three sides. Similarly the volume of a tetrahedron can be given as an algebraic function of the lengths of its six edges. The proof of this result is usually obtained by using vector methods. The following dis- cussion gives a more elementary derivation of this interesting result.
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    Some aspects of modern cosmology
    (Tira Pustaka, Jakartal, 1985-10-29) Narlikar, J. V.
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    Relationship of local time asymmetry to cosmology
    (World Scientific, 1985-10-14) Narlikar, J. V.
    Biological evolution implies time-asymmetry. Thermodynamics also exhibits time asymmetry through its second law. Electromagnetic radiation is a time asymmetrical phenomenon. It is suggested that the various time asymmetrical phenomena in nature are related and their understanding may require us to consider the large scale structure of the universe. Some ideas which relate cosraological time asymmetry to the one-sidedness of radiation are described. It is also suggested that issues relating to the foundations of quantum theory such as the collapse of the wavefunction, on interaction with the observer might be related to the large scale structure of the universe.
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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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    Very early universe : Problems and perspectives
    (Astronomical Society of India, 1985-03-29) Narlikar, J. V.
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    Creation field cosmology : A possible solution to singularity, horizon and flatness problems
    (American Physical Society, 1985-10-15) Narlikar, J. V.; Padmanabhan, T.
    A solution of Einstein s equations which admits radiation and a negative-energy massless scalar creation field as a source is presented. It is shown that the cosmological model based on this solu- tion satisfies all the observational tests and thus is a viable alternative to the standard big-bang model. The present model is free from singularity and particle horizon and provides a natural ex- planation for the flatness problem. We argue that these features make the creation-field cosmologi- cal model theoretically superior to the big-bang model.
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    Big bang and quantum cosmology
    (-, 1985-09-05) Narlikar, J. V.
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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.