The Universe

It is with great joy that we present a collection of essays written in honour of Jayant Vishnu Narlikar, who completed 60 years of age on July 19, 1998, by his friends and colleagues, including several of his for­ mer students. Jayant has had a long research career in astrophysics and cosmology, which he began at Cambridge in 1960, as a student of Sir Fred Hoyle. He started his work with a big bang, expounding on the steady state theory of the Universe and creating a new theory of gravity inspired by Mach's principle. He also worked on action-at-a-distance electrodynamics, inspired by the explorations of Wheeler, Feynman and Hogarth in that direction. This body of work established Jayant's rep­ utation as a bold and imaginative physicist who was ever willing to take a fresh look at fundamental issues, undeterred by conventional wis­ dom. This trait, undoubtedly inherited from his teacher and mentor, has always remained with Jayant. It is now most evident in his untir­ ing efforts to understand anomalies in quasar astronomy, and to develop the quasi-steady state cosmology, along with a group of highly distin­ guished astronomers including Halton Arp, Geoffrey Burbidge and Fred Hoyle. In spite of all this iconoclastic activity, Jayant remains a part of the mainstream; he appreciates as well as encourages good work along conventional lines by his students and colleagues. This is clear from the range of essays included in this volume, and the variety and distribution of the essayists.

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Preface. 1. Observations and Theory; H. Arp. 2. Ejection from Ultraluminous Infrared Galaxies; H. Arp. 3. Quantum Mechanics of Geometry; A. Ashtekar. 4. Quantum Mechanics and Retrocausality; D. Atkinson. 5. Instantons for Black Hole Pair Production; P.M. Branoff, D.R. Brill. 6. The Origin of Helium and the Other Light Elements; G. Burbidge, F. Hoyle. 7. Superluminal Motion and Gravitational Lensing; S.M. Chitre. 8. Dual Spacetimes, Mach's Principle and Topological Defect; N. Dadhich. 9. Noncosmological Redshifts of Quasars; P.K. Das. 10. Extragalactic Fire-Works in Gamma-Rays; P.D. Gupta. 11. Instabilities in Optical Cavities of Laser Interferometric Gravitational Wave Detectors; S.V. Dhurandhar. 12. The Epistemology of Cosmology; G.F.R. Ellis. 13. Mathematics and Science; F. Hoyle. 14. Radiation Reaction in Electrodynamics and General Relativity; B.R. Iyer. 15. Gravitational Collapse: The Story so far; P.S. Joshi. 16. Thoughts on Galactic Magnetism; K. Subramanian. 17. The Black Hole in MCG 6-30-15; A. Kembhavi, R. Misra. 18. Inhomogeneous Cosmological Models and Symmetry; S.D. Maharaj. 19. The Black Hole Information Paradox: What Have we Learnt From String Theory? S.D. Mathur. 20. The Counting of Radio Sources: A Personal Perspective; J.V. Narlikar. 21. A Variational Principle for Time of Arrival of Null Geodesics; E.T. Newman, S. Frittelli. 22. Conceptual Issues in Combining General Relativity and Quantum Theory; T. Padmanabhan. 23. Open Inflation in Higher Derivative Theory; B.C. Paul, S. Mukherjee. 24. The Non-Homogeneous and Hierarchical Universe; J.-C. Pecker. 25. Electromagnetic Wave Propagation in General Spacetimes with Curvature and/or Torsion (U4); A.R. Prasanna, S. Mohanty. 26. A Fresh Look at the Singularity Problem; A.K. Raychaudhuri. 27. Probing Beyond the Cosmic Horizon; T. Souradeep. 28. The Kerr-Nut Metric Revisited; P.C. Vaidya, L.K. Patel. 29. Black Holes in Cosmological Backgrounds; C.V. Vishveshwara. 30. Elementary Particle Interactions and Noncommutative Geometry; K.C. Wali. 31. From Interstellar Grains to Panspermia; N.C. Wickramasinghe.