Meghnad Saha

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Meghnad Saha

Meghnad Saha
Born	6 October 1893 Shaoratoli, Dhaka (Present day Bangladesh)
Died	16 February 1956
Residence	India
Nationality	Indian
Field	Physics
Institution	Allahabad University University of Calcutta
Alma mater	Dhaka College Presidency College, Kolkata
Known for	Thermal ionisation

Meghnad N. Saha (Bangla:মেঘনাদ সাহা) (Devanagari: मेघनाद साहा) (October 6, 1893 – February 16, 1956) was a Bengali Indian astrophysicist. He was born on 6 October, 1893 in Shaoratoli village near Dhaka in current day Bangladesh. He studied in Dhaka Collegiate School, and later in Dhaka College. He was a student at the Presidency College, Kolkata; a professor at Allahabad University from 1923 to 1938 and thereafter a professor and Dean of the Faculty of Science at the University of Calcutta until his death in 1956. He became Fellow of the Royal Society in 1927. He was president of the 21st session of the Indian Science Congress in 1934.

In his book, The Scientific Edge, the noted physicist Jayant Narlikar observed:

"Meghnad Saha’s ionization equation (c. 1920), which opened the door to stellar astrophysics” was one of the top ten achievements of 20th century Indian science [and] could be considered in the Nobel Prize class." ^[1]

Son of Jagannath Saha he belonged to a poor family and struggled to rise in life. He was fortunate to have brilliant teachers and class fellows. In his student days, Jagadish Chandra Bose and Prafulla Chandra Roy were at the pinnacle of their fame. Amongst his class fellows were Satyendra Nath Bose, Jnan Ghosh and J.N.Mukherjee. In later life he was close to Amiya Charan Banerjee, a renowned mathematican at Allahabad University.

He invented an instrument to measure the weight and pressure of solar rays. He produced the famous equation which he called 'equation of the reaction - isobar for ionization' which later became known as Saha's "Thermo-Ionization Equation", or the Saha Equation. According to the Scientific American, this equation became the foundation for the field of astrophysics.^[2]

Meghnad Saha's basic work was on the Thermal ionisation of elements and it led him to formulate what is known as the Saha equation. (When an element is heated to a very high temperature, the electrons in its atom get enough energy to break free from the atom. This process is known as Thermal ionisation.) Saha's equation is one of the basic tools for interpretation of the spectra of stars in astrophysics. By studying the spectra of various stars, one can find their temperature and from that, using Saha's equation, determine the ionisation state of the various elements in the star. He was also associated with building several scientific institutions like the Physics Department in Allahabad University and the Institute of Nuclear Physics in Calcutta. He founded the journal "Science and Culture" and was the editor till his death. ^[3]

Saha was the leading spirit in organizing the scientific societies like the 'National Academy of Science' (1930), the 'Indian Physical Society' (1934), 'Indian Institute of Science' (1935) and the 'Indian Association for the Cultivation of Science' (1944). The lasting memorial to him is the Saha Institute of Nuclear Physics founded in 1943 in Kolkata.

He was also the chief architect of river planning in India. He prepared the original plan for Damodar Valley Project.

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