Abhay Ashtekar, Penn State University, USA (09:30 - 10:30)
Title: The Big Bang and the Quantum
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Romesh Kaul, IMSc, Chennai (10:30 - 11:30)
Title: Topological Parameters in Theory of Gravity
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Ajit Kembhavi, IUCAA, Pune (12:00 - 13:00)
Title: Galaxy Morphology, Supermassive Black Holes and all that
Abstract: The morphology of galaxies, after suitable averaging over various complexities in the structure, can be described in terms of a small number of parameters which define the galaxy brightness distribution and linear scale. I will discuss correlations between such parameters which lead to insights into the mechanisms of galaxy formation and evolution. I will also consider correlations between these parameters and the masses of supermassive black holes which are found at the centres of galaxies.
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S R Kulkarni,Caltech, USA (14:30 - 15:30)
Title: Astronomy on the Cusp: A Subject Driven by Progress in Technology
Abstract: Astronomy enjoys the double reputation of being the second oldest profession and a romantic subject. Astronomy, by all accounts, is currently in its golden phase with even greater promises as we start this new decade. What is less well known and less appreciated is that astronomy is now one of the most expensive sciences and that astronomy both contributes to high technology (e.g. CCDs and sensors, radio engineering, explosion modeling) and is a major benefeciary of technological gains (primarily Moore's law and the law of synergestic returns). The speaker will first summarize the state (composition of the Universe, the build up of elements since Big Bang, strong gravity) of the field and then remark on the future interplay between astronomy and technology.
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J V Narlikar,IUCAA, Pune (16:15 - 17:15)
Title: Chandra's influence on Indian astronomy
Abstract: The extraordinary achievements of Subrahmanyan Chandrasekhar (Chandra) have guided and inspired many younger astrophysicists. The brief survey seeks to highlight a few specific cases in India where, through his writings, lectures and discussions, Chandra made a lasting impact. It will be argued that although at a general, somewhat super- ficial level, Chandra is a light beacon to be followed, very few Indian astrophysicists reached a level where they could engage Chandra in a scientific discussion on a topic that interested him.
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P C Agrawal, TIFR, Mumbai (09:30 - 10:30)
Title: High energy Universe Viewed Through Astrosat's eyes
Abstract: Astrosat is the first Indian satellite devoted fully to astronomical studies. It will have a broad spectral band observation capability covering optical, near and far ultra-violet and soft and hard X-ray bands. A unique feature of Astrosat is simultaneous observation capability of cosmic sources in these wavebands with four co-aligned instruments mounted on the top deck of the satellite. This will be achieved with 3 co-aligned X-ray instruments covering 0.5-100 keV region and a twin telescope Ultra-violet instrument sensitive in spectral band 120-260 nm. A Scanning Sky X-ray Monitor will monitor intensity of variable X-ray sources and detect transients. Astrosat is aimed at timing, spectral and imaging studies of a variety of galactic and extragalactic objects in X-ray and UV bands. These include X-ray binaries with a neutron star or black hole as the X-ray source, hot white dwarfs , early type hot stars , supernovae remnants, stellar coronae, normal galaxies, active galactic nuclei with massive black hole as the energy source etc. A brief description of the Astrosat instruments and their characteristics will be presented. The instruments capabilities will be illustrated with suitable examples for different types of sources.
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S R Kulkarni, Caltech, USA (10:30 - 11:30)
Title: The Restless Universe (Palomar Transient Factory)
Abstract: Only about a hundred years ago astronomers came to recognize cosmic explosive events. What was once termed as Stella Nova are now divided into two major families, novae and supernovae (with real distinct classes in each). The variables and the explosions have been interesting in their own right and contributed richly to key problems in modern astrophysics: distances to galaxies and cosmography. The area of transient and variable stars is once again undergoing a renaissance due to wide field optical surveys. The Palomar Transient Factory (PTF) was designed to explicitly to chart the transient sky with a particular focus on events which lie in the nova-supernova gap. PTF is now finding an extragalactic transient every 20 minutes and a Galactic (strong) variable every 10 minutes. Spectroscopy undertaken at Keck and Palomar has allowed us: identify an emerging class of ultra-luminous supernovae, discover luminous red novae, undertake UV spectroscopy of Ia supernovae, discover supernovae powered by something other than Nickel-56, clarification of sub-classes of core collapse and thermo-nuclear explosions, map the systematics of core collapse supernovae, a trove of eclipsing binaries, AM CVns and many others.
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Naresh Dadhich, IUCAA, Pune (12:00 - 13:00)
Title: Some universal features of gravity in higher dimensions
Abstract: We would first discuss some classical arguments for higher dimensions. We would derive the gravitational dynamics for Einstein as well as for Lovelock theory by using the Bianchi derivative and would also argue that $\Lambda$ is a true constant of spacetime and its identification with vacuum energy is not appropriate. It turns out that all the vacuum solutions of Einstein-Lovelock as well as pure Lovelock equation with $\Lambda$ always tend to the corresponding Einstein solution asymptotically. There also exists universality of gravity inside a uniform density sphere for Einstein as well as Einstein-Lovelock theories and for any dimension greater than equal to the usual four.
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Pankaj Joshi, TIFR, Mumbai(14:30 - 15:30)
Title: Final Fate of a Massive Star
Abstract:We review here several recent developments, related to the gravitational collapse of a massive star and its final fate. Massive stars collapse continually under the force of their own gravity when they exhaust their internal nuclear fuel. The outcome could be a black hole or a naked singularity, depending on the initial configuration of the star, in terms of its initial configurations such as initial densities, pressures and velocity profiles. The implications for the high energy astrophysics and very high energy phenomena in the universe are indicated.
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Abhay Ashtekar, Penn State University, USA (16:00 - 17:00)
Title: The Many Faces of Black Holes
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SPECIAL LECTURE : David Gross, The Kavli Institute for Theoretical Physics, USA(18:00 - 19:00)
Title: The Coming Revolutions in Fundamental Physics
Abstract:I review the present state of knowledge in elementary particle physics
and the questions that we are currently addressing. I discuss the experimental revolutions that might
occur at the Large Hadron Collider, soon to be finished at CERN. I shall also review the state of string
theory. The necessity to go beyond the standard model of particle physics and to understand quantum gravity
has led to this ambitious attempt to unify all the forces of nature and all forms of matter as different
vibrations of a string-like object. But string theory is still in a pre-revolutionary stage. Although
remarkable progress has been achieved in the last decade we still lack a fundamental understanding of the
theory. Many string theorists suspect that a profound conceptual change in our concept of space and time will
be required for the final formulation of string theory.
Note: This is the inaugural lecture of the series,
"Frontiers in High Energy Physics", with lectures throughout 2011, in celebration of Prof. G. Rajasekaran's 75th
birthday.
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Priyamvada Natarajan, Yale, USA (09:30 - 10:30)
Title: The formation and evolution of black hole seeds
Abstract: A review of the current status of our understanding of the formation, assembly and growth history of black holes through cosmic time will be presented. There has been tremendous progress both in observations of accreting black holes and our theoretical understanding of the relevant physical processes. New results on the formation of massive black hole seeds in the early Universe and their late time consequences and the evidence for merging black holes will be also presented.
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Ramesh Narayan, Harvard-Smithsonian, USA (10:30 - 11:30)
Title: The Black Hole Event Horizon
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Joseph Samuel, RRI, Bengaluru (12:00 - 13:00)
Title: The Universe in a Soap Film
Abstract: This talk develops an analogy between the surface tension of membranes and the cosmological constant of the Universe. The analogy is a mathematical one based on the usual connection between field theory and statistical mechanics. It leads to a better understanding of recent proposals to explain the small value of the cosmological constant. The analogy helps to bring abstruse quantum gravity effects down to earth and into the laboratory.
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Suneeta Varadarajan, IISER, Pune (14:30 - 15:30)
Title: Studying quantum stability of black holes
Abstract: One of Chandrasekhar's notable contributions was in investigating the classical stability of black holes in general relativity. In this talk, we will describe an approach to studying the stability of black holes in quantum gravity. This approach has connections to the study of stability of these black hole geometries under Ricci flow, which is an exciting area of research in mathematics. Interestingly, many of the techniques of Chandrasekhar and others in their study of classical stability of black holes can be used to study quantum stability and also offer insights into the mathematical problem of stability under Ricci flow . We will illustrate this by a result on the quantum stability of Schwarzschild-Tangherlini black holes in this approach.
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Giuseppina Fabbiano, Harvard-Smithsonian, USA (16:00 - 17:00)
Title: The Chandra X-ray Observatory
Abstract: Since its launch on July 23, 1999, the Chandra X-ray Observatory has been NASA's flagship mission for X-ray astronomy, taking its place in the fleet of "Great Observatories. "NASA's premier X-ray observatory was named the Chandra X-ray Observatory in honor of the late Indian-American Nobel laureate, Subrahmanyan Chandrasekhar. Chandra has imaged the spectacular, glowing remains of exploded stars, and taken spectra showing the dispersal of elements. Chandra has observed the region around the supermassive black hole in the center of our Milky Way, and found black holes across the Universe. Chandra has traced the separation of dark matter from normal matter in the collision of galaxies in a cluster and is contributing to both dark matter and dark energy studies. As its mission continues, Chandra will continue to discover startling new science about our high-energy Universe.
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T.Padmanabhan, IUCAA, Pune(09:30 - 10:30)
Title: What does classical gravity tell us about quantum structure of space time?
Abstract: I present the theoretical evidence which suggests that gravity is an emergent phenomenon like gas dynamics or elasticity with the gravitational field equations having the same status as, say, the equations of fluid dynamics/elasticity. This paradigm views a wide class of gravitational theories --- including Einstein's theory --- as describing the thermodynamic limit of the statistical mechanics of `atoms of spacetime'. The evidence for this paradigm is hidden in several classical features of the gravitational theories and depends on just one quantum mechanical input, viz. the existence of Davies-Unruh temperature of horizons. I discuss several conceptual ingredients of this approach.
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P. Majumdar, SINP, Kolkata (10:30 - 11:30)
Title: Chandrasekhar Mass Limit and Quantum Gravity
Abstract: Heuristic arguments are presented to provide a link between the Chandrasekhar lower bound on the mass of stellar cores undergoing gravitational collapse to a black hole, and black hole thermodynamics as understood on the basis of non-perturbative quantum gravity.
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Saurya Das, Lethbridge, Canada(12:00 - 13:00)
Title: A new uncertainty principle from quantum gravity and its implications
Abstract: Most theories of quantum gravity predict the existence of a minimum measurable length, taken normally to be the Planck length, and a modification of the Heisenberg uncertainty principle near that length scale, to a so-called Generalized Uncertainty Principle or GUP. We examine whether the GUP can have potential experimental signatures in low energy laboratory systems. We also show that it strongly suggests discreteness of space at the fundamental level, and explore possible implications.
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V.Madhavan, RRI, Bengaluru (14:30 - 15:30)
Title: Black Hole Evaporation from the perspective of Quantum Gravity
Abstract: First I review Hawking's picture of black hole evaporation and the ensuing Information Loss Problem. Next, I describe an alternate view, due to Ashtekar and Bojowald, of the evaporation process in the presence of singularity resolving quantum gravitational effects. Finally, I describe the results of a detailed analysis of the evaporation of 2 dimensional black holes which yield a picture similar to the qualitative Ashtekar - Bojowald one. In particular, the results support a scenario wherein quantum gravitational effects open up a quantum extension of classical spacetime beyond the singularity wherein information is recovered by sufficiently long lived observers.
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Ramesh Narayan, Harvard-Smithsonian, USA (16:00 - 17:00)
Title: Astrophysical Black Holes
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Rajaram Nityananda, TIFR, Mumbai (09:30 - 10:30)
Title: Chandrasekhars' contribution to the field of radiative transfer : an appreciation
Abstract: By his own account, Chandrasekhar derived a special satisfaction from his work on radiative transfer, with the peak being a problem as mundane as the polarisation of skylight. This is surprising in view of the very profound problems he addressed both earlier and later in his career. This talk will attempt to analyse why this might be so, by conveying the way he posed the problem, and solved it, using very general principles of invariance as well as considerable ingenuity.
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Shankaranarayanan S, IISER, Thiruvananthapuram (10:30 - 11:30)
Title: Entanglement entropy in all dimensions
Abstract: Hawking radiation and Bekenstein--Hawking entropy are the two robust predictions of a yet unknown quantum theory of gravity. Any theory which fails to reproduce these predictions is certainly incorrect. However, a clear understanding of the microscopic degrees of freedom giving rise to this entropy still lacking. It is important to explore all possible avenues. One proposal which stands out for its simplicity and generality is entanglement entropy. In this talk, we show that the entanglement of modes across the horizon in higher dimensions is proportional to higher dimensional area. We also discuss generic subleading corrections that this lead to in all dimensions. We examine implications of our results.
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