Research Publications

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Mahasphotochya parshwabhumivar umatleli paulchine?
(Maharashtra Times, 17-02-02) Naralikar, J.V.
Mazi kalpak aai
(Ravivar sakal, 20-04-02) Naralikar, J.V.
Stars in our eyes:Watching a celestial cricket match
(The Times of India, 21-09-02) Naralikar, J.V.
Galaxies
(Observatory, 1961-02-10) Naralikar, J.V.
On the counting of radio sources in the steady-state
(Wiley-Blackwell, 1961-06-13) Hoyle, F.; Narlikar, J. V.
The problem of the number count of radio sources as a function of the incident flux is shown to depend on two crucial features: (i) the size and behaviour of condensations (ii) the dependence on age of the probabillty of a galaxy being a radio source. Provided the probability rises by a factor 102 for galaxies with ages from H-1 to about -1, and provided the primary condensations of the steady-state theory possess initial dimensions of order 30 megaparsecs, the radio source count can rise more steeply than is the case for sources umformly distributed in Euclidean space. Each primary condensation contains of the order of io galaxies, which in the main expand apart from each other as the universe expands. It is shown that a luminosity function can be chosen for the radio sources giving results consistent with observation, not only for the source count, but also with the data on angular diameters and with experience in the problem of optical identifications.
Rotating universes
(Academic Press, 1961-07-10) Narlikar, J. V.
Steady state model and the ages of galaxies
(Bibliopolis, 1962-02-10) Hoyle, F.; Narlikar, J. V.
Neutrinos and the arrow of time in cosmology
(Royal Society, 1962-06-05) Narlikar, J. V.
Hogarth's approach to the time-symmetric electrodynamics of Wheeler & Feynman is extended to apply to the neutrinos. It is shown that in some cosmological models neutrinos travelling both into the past and the future exist whereas in others only those going into the the future can exist. The Einstein-de Sitter and the steady-state models are the respective examples of the two cases. An interesting way of testing the various cosmologies by means of neutrino emitters and receivers is suggested.
On the counting of radio sources in the steady-state cosmology, II
(Wiley-Blackwell, 1962-07-05) Hoyle, F.; Narlikar, J. V.
The existence of large scale condensations introduces a discrete element into the steady state theory. This discreteness assumes crucial importance where the counting of an age-correlated property is it may do in the case of radio sources. The discrete nature of the problem makes it awkward to deal with analytically. A different method using a high speed computer was therefore tried recently. This approach and the results obtained from it are discussed in this paper. There is a good agreement between the results and those obtained earlier by an analytical method.
Mach's principle and the creation of matter
(Royal Society, 1962-11-27) Hoyle, F.; Narlikar, J. V.
Mach's principle and the creation of matter
(Royal Society, 1963-04-23) Hoyle, F.; Narlikar, J. V.
Accurate experiments have shown that the local inertial frame is the one with respect to which the distant parts of the universe are non-rotating. This coincidence, first noticed by Newton, later led to the ormulation of Mach's principle. It is known that relativity theory by itself cannot explain this coincidence. The introduction of a scalar 'creation field' into the theory is likely to improve the situation. Calculation shows that the continuous creation of matter has the effect of smoothing out any irregularities in the universe as itexpands, while rotation, if present, becomes less and less. This explains the observed remarkable degree of homogeneity and isotropy in the universe.
Time symmetric electrodynamics and the arrow of time in cosmology
(Royal Society, 1963-05-01) Hoyle, F.; Narlikar, J. V.
This paper seeks to establish a connexion between the local arrow of time given by the electromagnetic radiation and the cosmological arrow of time given by the expansion of the universe. The Wheeler-Feynman absorber theory of radiation is applied to the expanding cosmological models. First, it is shown that the Schwarzschild-Tetrode-Fokker principle of direct interparticle action can be extended to the general Riemannian space-time. This generalization is considerably simplified in the conformally flat spaces-as all the Robertson-Walker spaces are. In the application of the absorber theory to various cosmo- logical models, the refractive index turns out to play a crucial part. The ambiguities con- nected with the sign of the imaginary part of the refractive index are resolved if two conditions are fulfilled: (i) a search is made for a self-consistent solution withfull retarded (or advanced) solutions (ii) in an elementary theory the origin of the imaginary part of the refractive index is traced to the radiative reaction itself and not to the collisional damping considered by Hogarth. It is shown that full retarded solutions are consistent in the steady-state cosmology and full advanced solutions in the Einstein-de Sitter cosmology. Full advanced solutions are not consistent in the former and full retarded solutions in the latter. Some interesting implications of this result in the C-field approach to the steady-state cosmology are considered.
Newtonian universes with shear and rotation
(Wiley-Blackwell, 1963-05-10) Narlikar, J. V.
Cosmological models involving shear and rotation are considered within the framework of Newtonian theorv. It is shown that, under certain assumptions, a differential equation can be obtained for the volume expansion factor. The solutions of this equation show that it is not possible to get non-singular finitely oscillating cosmological models.
Gravitational collapse
(Discovery, 1964-01-10) Naralikar, J.V.
On the behaviour of radiation near massive bodies
(American Astronomical Society, 1964-04-04) Faulkner, J.; Hoyle, F.; Narlikar, J. V.
The problem of communication between an observer on the surface of a massive body and an externa 1 Schwarzschild observer is examined. It is shown that when the body is freely imploding a signal from the external observer never reaches the surface provided the Schwarzschild coordinate of the external observer exceeds a critical value depending on the mass and radius of the body. The signals that reach the surface are redshifted. Time reversal of the solution then shows that radiation from an exploding massive body will be blueshifted when it reaches an external observer. This effect may supply the explanation for the origin of high-energy particles and quanta.
Neutrinos and the absorber theory of radiation
(Gauthier-Villars, 1964-04-15) Narlikar, J. V.
On the avoidance of singularities in C-field cosmology
(Royal Society, 1964-04-21) Hoyle, F.; Narlikar, J. V.
It is well known that a spherically symmetric imploding cold body collapses into a space- time singularity in general relativity. The singularity does not arise, however, in the modifica- tion of the theory proposed in C-field cosmology. Although the C-field has been used to represent creation of matter, the prevention of singularities does not depend on the creation property of the field, but on its negative energy density. It does not seem that singularities can be prevented except by a negative energy field. Internal pressures of the ordinary kind fail to provide support against gravitation provided the mass of the body is sufficiently large.
New theory of gravitation
(Royal Society, 1964-06-11) Hoyle, F.; Narlikar, J. V.
Electromagnetic waves from very dense stars
(Nature Publishing Group, 1964-08-29) Hoyle, F.; Narlikar, J. V.; Wheeler, J. A.
On the gravitational influence of direct particle fields
(Royal Society, 1964-11-03) Hoyle, F.; Narlikar, J. V.
The problem of the contribution of direct particle interaction of the Fokker type to the gravitational equations is solved. It is shown that the usual procedure for obtaining the gravitational equations, of making small variations of geometry, gik+8 ik replacing Gik in finite regions, with Ago I = 0 on their boundaries, and of requiring that the action be stationary for such variations, can be carried through with the aid of Green functions. This procedure, due to Hilbert, serves to define the energy tensor Tik associated with each of the fields. That for the C-field turns out exactly the same as we have used in the macroscopic form of the theory. That for the electromagnetic field turns out to have some new features. These are terms containing the vector potential and its derivative when world-lines are broken, although these terms vanish when there is charge conservation. The terms in the field Fik are identical with the usual tensor if the field is calculated from retarded potentials. In former work no decision has been made on the form the tensor should take when the potentials are I (retarded + advanced). Wheeler & Feynman showed that alternative choices are possible and that a decision cannot be made from electromagnetic considerations alone. Our analysis leads to a unique result, the Frenkel tensor.