Purnangshu Kumar Roy and the S.N. Bose Tradition in Theoretical Physics by Charles Wesley Ervin Email: Wes [email protected] August, 2016
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Purnangshu Kumar Roy and the S.N. Bose Tradition in Theoretical Physics By Charles Wesley Ervin Email: [email protected] August, 2016 INTRODUCTION This year Calcutta University marks a historic mile- stone. One hundred years ago the university started teaching physics courses at the newly created College of Science and Technology. Three of the most brilliant Indian physicists of the twentieth century began their careers there. C.V. Raman, the first Palit Professor of Physics, was awarded the Nobel Prize in 1930 for his work on light scattering. The two young lecturers, Meghnad Saha and Satyendra Nath Bose, made major breakthroughs even sooner – Saha in 1920 for deriving the equation that accounts for the spectral classifica- tion of stars and Bose in 1924 for inventing the statisti- cal model that validated Einstein’s hypothesis of light quanta (the Bose Statistics). But this “golden age” of Calcutta physics was P. K. Roy (right) with Satyendra Nath Bose in London, short-lived. Saha went to Allahabad University in March, 1958. Roy studied theoretical physics with Bose for 1923, Bose decamped to Dacca University in 1924, ten years at Calcutta University and then earned his PhD at and Raman left in 1932 to become the first Indian di- Imperial College under Abdus Salam. This photo was taken when Bose came to London to be inducted Fellow of the rector of the Indian Institute of Science in Bangalore. Royal Society. Courtesy of Anjana Srivastava. After the war, however, there was something of a re- naissance. Bose returned in 1945 and gathered a team of talented research workers in the Physics Depart- ment and the Khaira Lab. In this article I focus on one of his outstanding protégés, Purnangshu Kumar Roy, who carried forward the tradition of the “golden years” of Calcutta physics. He studied mathematical physics – relativity, quan- tum mechanics, and unified field theory – with his mentor Bose for ten years and then went to London in 1957 to do his PhD in particle physics at Imperial College under Abdus Salam, the future Nobel Laureate. Upon his return to Calcutta, he joined Bose’s team at the Indian Association for the Cultivation of Science and in 1964 became Senior Scientist and then Reader in Pure Physics at Calcutta University. Roy could have had a successful academic career abroad. But like Bose, Roy was a Calcutta man at heart - a true Bengali intellectual who pursued science, culture, and politics with equal zest and who loved nothing more than spending hours in freewheeling group conversations in the smoky coffee shops near the university. Though he didn’t publish much after 1962, he pursed the latest developments in particle physics and the ongoing search for a Unified Field Theory. Sadly, he died of cancer in 1975, when he was only 50. I met Dr. Roy in Calcutta in 1974. After that, we lost contact. When I heard about the plans of Calcutta University to celebrate the centenary of its Physics Department, I wrote a short biographical sketch of Dr. Roy for the commemoration volume.1 This expanded article places him in broader context. I express my gratitude to his daughter, Anjana Srivastava, in Mumbai and his nephew, Mukul Roy, in Kolkata for provid- ing critical biographical information and his former colleagues and students for sharing their recollections. FAMILY BACKGROUND AND UPBRINGING P.K. Roy was born into a middle-class Bengali family with ancestral roots in Howrah, across the Hoogli River from Calcutta. His grandfather, Beni Madhab Roy, owned land there. They were Vaidyas in caste. The Vaidyas considered themselves to be of the same high caste as Brahmins. P.K. Roy’s father, Raj Kishore, was a college graduate who secured a good government job in the Defense Accounts Department. In 1908 he was transferred from Howrah to Meerut, an old town northwest of Delhi. His wife, Radha, bore him eight children – five sons and three daughters. Purnangshu was the youngest, born February 10, 1925. The sons were given names that referred to the Moon. Purnangshu is “full moon.” Raj Kishore was loyal to the Raj and he rose to a middle rank in the bureaucracy. He was very cultured. He wrote poetry, and the sound of music often filled the home. His sons remember him as a patriarch and they always addressed him with the respectful “you” (apni), which was common in those days. He knew that education was the ticket to a good salaried job in the British administration and he sent the children to English-medium schools. But in the home, the traditional Bengali culture prevailed. Like many Bengalis to this day Raj Kishore and Radha gave their children nicknames or petnames (dak nam). Purnangshu was “Nitai” - shortened from Nityananda, the 15th century Vaishnava saint who was an important religious fig- ure within the Gaudiya Vaishnava tradition of Bengal. For the rest of his life, Purnangshu went by “Nitai.” After retiring from government service in 1926, Raj Kishore decided to move the family back to Cal- cutta. He bought a plot of land in Nanda Kumar Chaudhuri Lane, a narrow street barely ten feet wide, tucked away behind the intersection of bustling Vivekananda Road and Cornwallis Street (now Bidhan Sarani). This was an old residential area of North Calcutta, populated by bhadralok families whose wealth came from land their ancestors had acquired from the British as a result of the Permanent Settlement. With borrowed money he built a large, three-story house for the joint family. His wife died in childbirth before it was finished in 1928. He installed plaque on the front of the house with the dedication, Radha-Kun- ja [abode of Radha]. The plaque is intriguing. In those days devout Vaishnava families often put up plaques that referred to the god Krishna (Krishna Kunja - the abode of Lord Krishna). Dedications to the godess Radha were tradi- tionally suffixed by Krishna’s name, e.g., Radhamad- hav, Radhavinod, etc. “Radha” rarely stands alone. So “Radha-Kunja,” could refer to either the Vaishnava tradition or his wife, or perhaps both. Purnangshu grew up in this house, surrounded by his brothers and sisters, nieces and nephews, and domestic helpers. On the ground floor there were two large parlors, an interior courtyard with water tank, kitchen, and servants’ quarters. The elder brothers lived on the second floor. Purnangshu, being the youngest, had a small room on the top floor. At one point there were a total of 42 people living there. There was only The Roy residence, 13 Nanda Kumar Chaudhuri Lane, one bathroom for the entire household. There was no North Calcutta. The dedication plaque from 1928 is on the wall next to the entrance. Courtesy Anjana Srivastava. yard outside, so the children congregated on the stair- way. Despite the cramped quarters, they loved the house and being a tight-knit joint family. Page 2 A MATHEMATICS WHIZ Roy was schooled at Scottish Church Collegiate School, one of the old- est English-medium educational institutions in India. The school had top-quality teaching staff, a well-stocked library, and up-to-date labora- tory. Roy was precocious; his room was filled with books on all sorts of subjects. But he wasn’t a bookworm. He made many friends at school. A relative described him as “very sincere, outgoing, and easy going.”2 He excelled in mathematics. In 1942 he passed the Intermediate Science Examination (ISc) in the First Division with a star and dis- Roy graduated with top honors from Scottish Church College in North Cal- tinctions in Mathematics, the highest score in the College. He won two cutta, not far from the Roy residence. prizes in Mathematics and two scholarships. He continued in the BSc Photo: Calcutta University (Honors) program at Scottish Church College. His father died in 1941. The elder sons kept the family afloat with their incomes. But the future looked precarious. The war was getting closer every day. The Japanese had routed the British in Burma and were massing forces at the border in preparation for an invasion of Bengal. Their planes bombed the Calcutta docks. Families boarded up their houses and fled the city. In August, 1942 the Quit India struggle erupted after the British arrested Gandhi and the entire Con- gress high command for their refusal to support the war. Purnangshu and his sister, Suprova, who was an economics student, joined the mass demonstrations. They got a quick lesson in politics. The Communist Party of India was supporting the British war effort in the name of defending Soviet Russia. Purnangshu and Suprova encountered a small group of Trotskyists (followers of the Russian revolutionary, Leon Trotsky, who was assassinated in his Mexico exile by a Stalinist agent in 1940). They were a very brainy lot who attacked the CPI from the left. Purnangshu and his sister joined the Trotskyist group.3 In 1944 Roy passed his BSc Examination with honors in Mathematics, ranking first among the students at Scottish Church College. The Principal sang his praises: “He was one of the most brilliant students of his time in College, obtaining uniformly high marks in his class examinations.”4 He matriculated in the MSc program in Applied Mathematics. The courses were given at the University College of Science, which was a constituent of the Calcutta University. FORMING A BOND WITH BOSE While pursuing his MSc, Roy met the famous physicist, Satyendra Nath Bose, who had returned to Calcutta in 1945 from Dacca University to become the Khaira Professor of Theoretical Physics at the Science Col- lege. Roy revered him like a demi-god. His teachers in the Applied Mathematics Department went to Bose for help with difficult problems or guidance.