Raj Kumar Pathria (born March 30, 1933) is a theoretical physicist, a Distinguished Professor Emeritus at University of Waterloo, and an Urdu poet.

[1][2] Pathria is known for his work on superfluidity in liquid helium, Lorentz transformation of thermodynamic quantities, an exact evaluation of lattice sums and finite-size effects in phase transitions.

He received his early education in a local high school and then joined the Hindu College, Amritsar for his FSc studies.

This maiden attempt at book-writing resulted in fabulous reviews from far and wide, especially from Professor William McCrea – who himself was a celebrated author on this subject.

In the early 1990s, when his new publishers (Butterworth-Heinemann) persuaded Pathria to produce a second edition of this text, he sought the help of Surjit Singh, a former student of his from the Chandigarh days (who had also been a postdoctoral fellow with him at Waterloo during the years 1983–87).

Having read and imbibed dozens of classics emanating from stalwarts like Mir, Ghalib, Zauq, Momin, Hali, Dagh and Iqbal, down to modernists like AsGhar, Fani, Hasrat, Jigar, Firaq and Faiz, Pathria finally turned to writing Urdu poetry himself – but only around the year 1993 when he was close to retirement from Physics.