How does an isolated quantum system come to thermal equilibrium due to interaction between its constituent subsystems? Or does it? What underlies the condition for quantum ‘ergodicity’?
These are some of the basic questions to be discussed in this talk. The topic is of fundamental importance since it deals with the applicability of thermodynamics and statistical mechanics to isolated quantum systems, and asks the extent to which an isolated (macroscopic) quantum system can ever be described by a temperature.
We have learnt a great deal about the physics of the Universe at length scales of the order of an atto-metre, i.e. a nano-nanometre. This talk will trace the history of these great discoveries from an experimental point of view (though the speaker is a theorist), mentioning the importance of new technologies in retrieving information about such tiny objects, and showing how new theoretical ideas went hand-in-hand with new and often unexpected experimental discoveries. Finally, mention will be made of the giant LHC machine running at CERN, Geneva and some of the challenges for the future.
One of the fundamental issues in Cell Biology is to understand how the living cell translates
physical and chemical processes to the management of information''. I will discuss how a transdisciplinary
approach might throw light on this problem and illustrate this with our many collaborative
research programs dealing with the active composite cell surface, organelle morphogenesis in
trafficking pathways and cellular homeostasis and control. In doing so, I hope to lay out a more nuanced
and ramified cross current of ideas and a richer engagement between theory and experiment, including
a more abstract face of theory and its experimental implications.
When a black hole forms, the final state is said to be independent of details of the initial state of the collapsing matter. This is reminiscent of the phenomenon of thermalization in non equilibrium systems. Indeed, these two phenomena are sometimes related by a duality. Yet, while we believe we know a lot about thermalization, there is an active debate about the nature of "information loss" in the black hole system. We will discuss both issues with a bit of history and some recent inter-related developments which yield insight into the black hole mystery.
Models of Earthquake Dynamics: Theory, Simulations &
Comparisons with Aftershock Data
Earthquake dynamics is still very poorly understood
and its physics models so far are not very successful.
After a very brief survey of earthquake statistics, I
will briefly present one "geometric" model and another
"elastic depinning" model developed by us and present
also their relative merits/successes when compared
with the available well-characterized aftershock
March 14, 2016
Amitava Raychaudhuri, Sir Tarak Nath Palit Professor of Physics, University of Calcutta
Burning of the Sun & Turning of the Earth: Probing Nature with Neutrinos
Fusion reactions in the sun produce heat and light – and neutrinos. Is the solar model correct? Are we receiving the expected number of neutrinos on earth? Neutrinos are also produced in the earth’s atmosphere by cosmic rays. We expect these to be of the same number from all directions. Is this what we see? Experiments to address these issues – involving very talented scientists and engineers – led to results which imply that neutrinos are massive particles, when it was commonly thought otherwise. The Physics Nobel Prize of 2015 was awarded to Takaaki Kajita and Arthur B. McDonald for their leadership of two of these experiments. We begin with a brief introduction to neutrinos and their properties. We next turn to the experimental results that establish they have non-zero mass. What other properties of neutrinos are known? What are the known unknowns? Where do we go from here? A brief overview is provided.
March 22, 2016
Prof. Arup Raychaudhuri, S.N. Bose National Centre in Basic Sciences
JD Block, Salt lake Sector III
The physics of metal-insulator transition is one of the most fascinating phenomena in modern day solid state sciences. It is well researched for years and ill understood, mostly. The process of transition from a metal (which has extended states) to an insulator (that has localized states) is not explainable within the frame work of a comprehensive theory till date, where disorder (e.g, those introduced by substitution) and electron correlation effects can be present together . In these schemes of things oxides form a new class that can have very highly resistive metallic phase co-existing with insulating phase.
This talk will present an account of experimental pursuits, some of them using new tools and techniques that allow us to get new perspectives of metal-insulator transition close to the critical region. The talk will have a pedagogic component that will explain some of the basic concepts in this field and some necessary data to elucidate the recent results . It will also have a component of personal accounts that contain the agony and ecstasy of doing experiments.