Research Papers (JVN)
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Item Reply to Professor Silk(Elsevier Science Publishers, 1999-03-18) Narlikar, J. V.Item Case against the big bang(Elsevier Science Publishers, 1999-04-14) Narlikar, J. V.This article takes a critical look at the Hot Big Bang Cosmology (HBBC). It shows that two of its strongest lines of evidence, viz the cosmic microwave background and the abundance of light nuclei are capable of being interpreted differently, and in a physically more realistic way the HBBC is shown to have shifted its ground frequently under observational constraints, changing its parameters like Ω0, Ωb, Ωλ and q0, reinterpreting inflation, bedging options on dark matter, etc. Many of its present deductions are seen to be based on untested physics and unobservable events of the very early Universe, while its beginning in a spacetime singularity indicates its incompleteness as a physical theory. The example of the quasi steady singularity indicates its incompleteness as a physical theory. The example of the quasi-steady state cosmology (QSSC) is given to demonstrate that an alternative cosmology relying more on the ongoing astrophysical properties of the Universe and directly observable events is possible. The case is therefore made that the HBBC does not hold the ‘monopoly’ to be THE model of the Universe.Item Cosmology(International Astronomical Union, 1999-05-18) Narlikar, J. V.Item Alternative cosmology: The QSSC(International Astronomical Union, 1999-03-24) Narlikar, J. V.This review begins with a brief survey of the observational constraints on the standard big bang cosmology, pointing out that the various limits leave a very narrow window in the parameter space of plausible models. There is thus a strong case for alternative cosmologies. The rest of the review concentrates on one alternative, the quasi steady state cosmology (QSSC) and summaries the recent work on this model. The includes the theoretical formulation and simple exact solution 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 Quantum mechanics via path amplitudes(IOP Publishing, 1999-04-14) Narlikar, J. V.Item Quasi-steady state cosmology : Theory and observations(Indian Academy of Sciences, 1999-12-14) Narlikar, J. V.This is a review of an alternative cosmology, recently proposed by Fred Hoyle, Geoffrey Burbidge and this author. It begins with a brief discussion of why one needs an alternative cosmology, when the standard hot big bang cosmology is claimed to be doing well. It is argued that the observational and theoretical constraints on the standard big bang cosmology, from various directions, leave a very narrow window, if any, in the parameter space of plausible models. There is thus a strong case for alternative cosmologies. The rest of the review concentrates on one alternative, the quasi steady state cosmology (QSSC) and summarises the recent work on this model. This includes, the theoretical formulation and simple exact solutions of the basic equations, their relationship to various observations, the stability of solutions and the toy model for understanding the growth of structures in the Universe.Item Structure formation in the quasi-steady state cosmology : A toy model(American Astronomical Society, 1999-11-01) Nayeri, Ali; Engineer, Sunu; Narlikar, J. V.The problem of formation of large-scale structure is discussed within the framework of the quasi-steady state cosmology (QSSC). The primary process of creation of matter and the resulting dynamics of ejection of matter from regions of strong gravitational Ðelds play a key role. To understand their workings, a toy model is used, in which from a set of randomly distributed creation centers a new generation of centers is created as part of an iterative algorithm. It is shown that the system develops clusters and voids along with filamentary structure, within a few iterations. The two-point correlation function and density distribution function for these simulations are shown to reproduce the observed clustering of the large-scale structure in the real universe.Item Quasi-steady state cosmology: A study of angular size against redshift(Wiley-Blackwell, 1999-02-25) Banerjee, Shyamal K.; Narlikar, J. V.The data on angular sizes and redshifts of ultracompact radio sources used by Jackson & Dodgson in a recent paper have been applied to the various theoretical models in the framework of the quasi-steady-state cosmology proposed by Hoyle, Burbidge & Narlikar. It is found that although acceptable fits to the data are available for the flat models, those with a negative curvature of spatial sections provide a better fit. These latter models require low densities of matter and as such do not demand too high a proportion of dark matter. A comparison is made with the work of Jackson & Dodgson and theoretical implications of the test are discussed.Item Theories and observations in cosmology(Indian National Science Academy, 1997-12-28) Narlikar, J. V.This account is meant to be both a review and a resource article for modern cosmology. In this sense it will highlight the recent developments in the subject and point to future trends; but in addition it will indicate to the reader wishing to go deeper into the various aspects of this field, the database and sources in the form of reviews, texts and conference reports.Item India: A status report on teaching of astronomy in India(Cambridge University Press, 1998-09-19) Narlikar, J. V.; Rana, N. C.