Meghnad Saha

Meghnad Saha was a prominent Indian astrophysicist who developed the theory of thermal ionisation and the Saha ionisation equation that explained the origin of stellar spectra. He was born on October 6, 1893 in Shaoratoli, a village near Dhaka in present-day Bangladesh. He was the fifth child of Jagannath Saha, a grocer, and Bhubneshwari Devi. He faced poverty and discrimination in his early life, but he was determined to pursue his education. He completed his primary and secondary education in Dhaka with the help of a local doctor who sponsored him. He then moved to Calcutta where he joined the Presidency College in 1911. He was a classmate of Satyendra Nath Bose, another eminent physicist. He studied under renowned teachers like Jagadish Chandra Bose and Prafulla Chandra Ray. He obtained his BSc in mathematics in 1913 and MSc in applied mathematics in 1915. He started his career as a lecturer in the Department of Applied Mathematics at the University College of Science, Calcutta in 1916. He began his research on thermal ionisation of elements without having access to a well-equipped laboratory or a research guide. He published his first paper on the subject in 1919 in the Philosophical Magazine. He derived an equation that related the degree of ionisation of an element to its temperature and pressure. This equation became known as the Saha ionisation equation and it revolutionised the field of astrophysics. It enabled astronomers to determine the temperature and chemical composition of stars by analysing their spectra. He received a scholarship from the Government of India to pursue further research in Europe in 1920. He worked at the Imperial College London under Alfred Fowler who was an expert on solar physics. He also visited other scientific institutions in Germany, France, and Denmark where he met and interacted with other eminent scientists like Niels Bohr, Albert Einstein, Max Planck, and Marie Curie. He returned to India in 1921 and resumed his teaching position at Calcutta. He continued his research on thermal ionisation and also ventured into other areas of physics such as nuclear physics, spectroscopy, X-ray crystallography, and cosmic rays. He made significant contributions to these fields and published several papers in reputed journals. He also collaborated with other scientists from India and abroad on various projects. He became a professor of physics at Allahabad University in 1923 where he established a new department of physics. He also founded the Institute of Nuclear Physics (now known as Saha Institute of Nuclear Physics) in Calcutta in 1938. He served as its director until his death. He was instrumental in developing nuclear physics research in India and training many young scientists. He was also involved in various scientific and educational activities outside his academic work. He was elected as a Fellow of the Royal Society in 1927 for his achievements in physics. He was also a member of several national and international scientific committees and organisations such as the Indian Association for the Cultivation of Science, the Indian Science Congress Association, the International Council for Science, and the Third World Academy of Sciences. He played a key role in formulating the National Calendar of India based on the Saka era which was adopted by the Government of India in 1957. He also chaired a committee that revised the Indian Shak Panchang which is used for astrological and religious purposes. He was also interested in social and political issues and advocated for scientific and industrial development in India. He was elected as a Member of Parliament in 1952 from the Calcutta North West constituency. He was married to Radharani Saha in 1920 and they had two daughters. His wife died in 1952. He suffered from heart problems and diabetes in his later years. He died of a heart attack on February 16, 1956 in New Delhi at the age of 62. He was cremated with full state honours. He is widely regarded as one of the greatest Indian scientists of the 20th century who made lasting impacts on physics and astrophysics.