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On Physics, Physicists and Philosophy On Physics, Physicists and Philosophy N. Mukunda # 1 All rights reserved. No parts of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior permission of the publisher. © Indian Academy of Sciences 2018 Reproduced from Resonance-journal of science education Reformatted by : Sriranga Digital Software Technologies Private Limited, Srirangapatna. Printed at: Tholasi Prints India Pvt Ltd Published by Indian Academy of Sciences # 2 Foreword The Masterclass series of eBooks brings together pedagogical articles on single broad top- ics taken from Resonance, the Journal of Science Education, that has been published monthly by the Indian Academy of Sciences since January 1996. Primarily directed at students and teachers at the undergraduate level, the journal has brought out a wide spectrum of articles in a range of scientific disciplines. Articles in the journal are written in a style that makes them accessible to readers from diverse backgrounds, and in addition, they provide a useful source of instruction that is not always available in textbooks. The fifth book in the series, ‘On Physics, Physicists and Philosophy’, is by Prof. N Mukunda. A very distinguished theoretical physicist, Prof. Mukunda worked at TIFR (Mum- bai) for a few years, and then at the Indian Institute of Science (Bengaluru) till 2001. He still remains actively engaged with science and regularly lectures to students around the country. Prof. Mukunda was the founding Chief Editor of Resonance, a journal that he steered with a very deft though unobtrusive hand during the initial years (1996–2000). I had the pleasure of serving on the Editorial Board of Resonance as a young assistant professor in those years, and I learnt a lot just by observing how Prof. Mukunda handled the trickiest of issues with firmness, underlain by an unflappable good-natured aplomb. Prof. Mukunda was also a very regular contributor to Resonance over the years, as the sheer number of articles in this collection tes- tifies. His engagement with pedagogical and educational issues has been widely recognized in India. He was instrumental in establishing and nurturing the science education initiatives and programmes of the three science academies in the country, and also served a long stint as Editor of Publications at the Indian Academy of Sciences, Bengaluru. Prof. Mukunda is very well known for his research contributions to the areas of classical and quantum mechanics, theoretical optics and mathematical physics. In addition, he has had a deep and abiding interest in philosophical issues in physics and, indeed, in science in gen- eral. The book, which will be available in digital format, and will be housed as always on the Academy website, will be valuable to both students and experts as a useful handbook on all kinds of topics in physics, ranging from technical and philosophical issues to sketches of the lives and work of eminent physicists, all rendered in Prof. Mukunda’s inimitable style. Amitabh Joshi Editor of Publications Indian Academy of Sciences February 2018 # 3 # 4 About the Author Professor Mukunda is a well-known theoretical physicist who has made many outstanding contributions to the areas of high energy physics, group theory, classical dynamics, classical and quantum optics and geometric phases in quantum mechanics. He is known for developing and applying group theoretic and phase space based methods to problems in theoretical physics. He worked with Prof E C G Sudarshan for his PhD (1964) at the University of Rochester USA, began his independent scientific career in TIFR Mumbai in 1967, and later (1972) moved to the Center for Theoretical Studies at IISc Bangalore, where he spent almost thirty years. Apart from his passion for research, he has a keen interest in physics teaching and science pedagogy at large. He was the architect of the first set of SERC schools in high-energy physics, and his lectures on group theory in these schools which appeared in the form of a monograph with S Mukhi have become an essential part of the training of anyone aspiring to become a theoretical physicist. He chaired the first Panel on Science Education formed in 1994 by the Indian Academy of Sciences, whose recommendations led to active Academy initiatives in the arena of science education. One among these initiatives is the science journal Resonance, for which Prof Mukunda served as the Founder-Editor. Prof Mukunda also helped shape KVPY in his capacity as its founder member and the first convener. Professor Mukunda is known for his unique style in which he practices and teaches physics. The flow of ideas in his lectures unfolds in a beautiful way and leaves a deep impression on his audience. He prepares and delivers his lectures with the same degree of zeal, enthusiasm and care for detail regardless of whether the audience stems from an elite institution or a small undergraduate college in a remote part of the country. As editor of Resonance, he has written several editorials in his characteristic style with insistence of clarity, elegance of expression and readability. Professor Mukunda is a connoisseur of cinema, especially Hollywood films of the black and white era. His demeanour is very simple, his lifestyle is appealingly minimalistic. The present volume brings together some of the writings of Professor Mukunda which have appeared in Resonance during the last two decades. These articles are wide-ranging in nature and range from book reviews (which are like mini-books in themselves!), reflections on science and philosophy, biosketches of physicists and several articles which bring out the subtle symmetry and invariance aspects of physics. This volume is an invaluable addition to the bookshelf of any serious student of physics not only for physics per se but also as a benchmark for clarity of thought and expression one should strive for. Arvind IISER Mohali # 5 # 6 Preface I am sincerely grateful to Professor Ramakrishna Ramaswamy, President of the Indian Academy of Sciences, for thinking of including my articles in Resonance in the Masterclass series of e-books being published by the Academy. Thanks also to Professor Amitabh Joshi, Editor of Publications, and Professor Arvind, for the very kind and generous sentiments ex- pressed in the Foreword and in ‘About the Author’. My formal association with Resonance as a member of the Editorial Board lasted for about eighteen years. Coincidentally the thirty one articles put together in this book also span eigh- teen years. The articles have been arranged in five groups in a natural way, based on the nature of content, length etc.Some are relatively long, others like Article-in-a- Box are short bio- graphical pieces. A few book reviews have also been included , hoping that they may be useful for younger readers.It was a pleasure to write each one of them, paying attention not only to content but also to language. Some of the articles written around 2005, the centenary of Albert Einstein’s ‘annus mirabilis’, were inspired by the need to communicate to Resonance readers the enormous significance of the occasion. They had to be written. My coauthors – V Balakrishnan, S Chaturvedi, K S Mallesh, V Natarajan, and R Simon – have very graciously agreed to have coauthored articles included in this collection, it is a pleasure to thank them . It was a rewarding experience to work with each one of them. Let me hope that my readers derive some enjoyment as well as some benefit from this collection. N Mukunda # 7 # 8 Contents Biographical Pieces Einstein’s Miraculous Year 3 with Vasant Natarajan and V Balakrishnan Eugene Paul Wigner – A Tribute 17 The Life and Work of Niels Bohr – A Brief Sketch 39 Bohr and Dirac 45 Enrico Fermi – Life, Personality and Accomplishments 55 Sir William Rowan Hamilton – Life, Achievements, Stature in Physics 63 General Articles The Story of the Photon 77 The Einstein–Podolsky–Rosen Paper – An Important Event in the History of Quan- tum Mechanics 91 with S Chaturvedi and R Simon The 2005 Nobel Prize in Physics: Optics 105 with Vasant Natarajan Space, Time and Relativity 119 with S Chaturvedi and R Simon Space and Time in Life and Science 131 with Vasant Natarajan and V Balakrishnan Symmetries and Conservation Laws in Classical and Quantum Mechanics: Classical Mechanics 147 with K S Mallesh, S Chaturvedi, V Balakrishnan and R Simon # 9 Symmetries and Conservation Laws in Classical and Quantum Mechanics: Quantum Mechanics 165 with K S Mallesh, S Chaturvedi, V Balakrishnan and R Simon States of Physical Systems in Classical and Quantum Mechanics 179 with K S Mallesh, S Chaturvedi and R Simon Reflections Science and the Human Condition 199 Einstein’s Life and Legacy 215 The Philosophy of the Physical Sciences 223 Brief Life Sketches Abdus Salam 239 About Wolfgang Pauli 241 Paul Adrien Maurice Dirac – An Appreciation 245 Lagrange and Classical Mechanics 249 Max Planck – Founder of Quantum Theory 251 Israel Moiseevich Gelfand – An Appreciation from a Physicist’s Viewpoint 255 Richard Phillips Feynman – Physicist and Teacher Extraordinary 257 Arnold Sommerfeld – Physicist and Teacher Beyond Compare 259 Book Reviews “The Story of Spin” – From Spectroscopy to Relativistic Quantum Mechanics 267 Profile of a Polymath 269 10 # 10 Erwin Schrodinger,¨ “What is Life? The Physical Aspect of the Living Cell” 271 ‘Mind from Matter? An Essay on Evolutionary Epistemology’ 275 Science and Hypothesis 279 Books by and about Werner Heisenberg 281 11 # 11 # 12 Biographical Pieces # 13 # 14 Einstein’s Miraculous Year∗ Vasant Natarajan, V Balakrishnan and N Mukunda With each passing year, the young Albert Einstein’s achievements in physics in the year 1905 seem to be ever more miraculous. We describe why the centenary of this remarkable year is worthy of celebration.
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