Saha and His Formula

This series, which is a sort of random walk in Physics, is mainly intended to arouse the curiosity of the serious reader, besides capturing the drama and excitement of great discoveries.

This volume deals with the life of Meghnad Saha and his epoch-making discovery which resulted in the birth of modern astrophysics.

The author, Dr. G. Venkataraman, started his career in the fifties at the Bhabha Atomic Research Centre, Mumbai , and has spent over a decade at the Indira Gandhi Centre for Atomic Research, Kalpakkam. He was, until recently, with the Defence Research and Development Organisation in Hyderabad. A condensed matter physicist, he has worked in some of the areas pursued earlier by Sir C. V. Raman. He is Fellow of the Indian National Science Academy and the Indian Academy of Science, and was formerly the President of the Indian Physics Association. He was awarded the Sir C. V. Raman Prize by the University Grants Commission in 1979, and was Jawaharlal Nehru Fellow from 1984 to 1986. In 1991 he was honoured with the Padma Shri. For his contributions to the popularization of Science, the Indian National Science Academy conferred on him the Indira Gandhi Award in 1994. In addition to the Monographs Dynamics of Perfect Crystals and Beyond the Crystalline State, Dr. Venkataraman is also the author of the widely acclaimed Journey Into Light: Life and Science of C. V. Raman. Dr. Venkataraman is currently the Vice-Chancellor of the Sri Satya Sai Institute of Higher Learning, Prasanthi Nilayam.

This book and others in this series written by me are inspired by the memory of my son Suresh who left this world soon after completing school. Suresh and I often used to discuss physics. It was then that I introduced him to the celebrated Feynman Lectures.

Hans Bethe has described Feynman as the most original scientist of this century. To that perhaps may be added the statement that Feynman was also the most scintillating teacher of physics in this century.

The Feynman Lectures are great but they are at the textbook level and meant for serious reading. Moreover, they are a bit expensive, at least for the average Indian student. It seemed to me that there was scope for small books on diverse topics in physics which would stimulate interest, making at least some of our young students take up later a serious study of physics and reach for the Feynman as well as the Landau classics.

Small books inevitably remind me of Gamow’s famous volumes. They were wonderful, and stimulated me to no small extent. Times have changed, physics has grown and we clearly need other books, though written in the same spirit.

In attempting these volumes, I have chosen a style of my own. I have come across many books on popular science where elaborate sentences often ten to obscure the scientific essence. I have therefore opted for simple English, and I don’t make any apologies for it. If a simple style was good enough for the great Enrico Fermi, it is also good enough for me. I have also employed at times a chatty style. This is deliberate. Feynman uses this with consummate skill, and I have decided to follow in his footsteps (whether I have succeeded or not, is for readers to say). This book is meant to be read for fun and excitement. It is a book you can even lie down in bed and read, without going to sleep I hope!

Naturally I have some basic objectives, the most important of which is to stimulate the curiosity of the reader. Here and there the reader may fail to grasp some details, and in fact I have deliberately pitched things a bit high on occasions. But if the reader is able to experience at least in some small measure the excitement of science, then my purpose would have been achieved. Apart from excitement, I have also tried to convey that although we might draw boundaries and try to compartmentalize Nature into different subjects, she herself knows no such boundaries. So we can always start anywhere, take a random walk and catch a good glimpse of Nature’s glory. Where she is concerned, all topics are “fashionable”. There is today an unnecessary polarization of the young towards subjects that are supposed to be fashionable. To my mind this is unhealthy, and I have tried to counter it.

This series is essentially meant for the curious. With humility, I would like to regard it as some sort of a “Junior Feynman Series”, if one might call it that. With much love, and sadness, it is dedicated to the memory of Suresh who inspired it.

The sun is often described as a great big ball of fire. It is in fact a star, and though there are billions and billions of stars in the Universe, the Sun is very special to us because it is our star. Recognising it as the source of energy for life on Earth, our ancients worshipped the Sun. In more recent times, worship of the Sun has declined but on the other hand, scientific study of it has greatly increased. The mysteries of the Sun have not been completely unraveled but all the same, we do know quite a bit about it. A great leap forward occurred way back in 1920 when Meghnad Saha made an important discovery which at one stroke not only swept away much of the prevailing confusion but also paved the way for a systematic study of stellar atmospheres in general. This book is about that great discovery and the man who made it.