Professor Raj Kumar Pathria is a theoretical physicist and an Urdu poet. He is known for his work on superfluidity in liquid helium, Lorentz transformation of thermodynamic quantities, a rigorous evaluation of lattice sums, and finite-size effects in phase transitions. Pathria obtained his BSc Honours degree in 1953 and MSc Honours degree in 1954 from Panjab University, Hoshiarpur, and earned a Ph.D. in Physics from University of Delhi in 1957. He has served on the physics faculties of the University of Delhi (1958-1964), McMaster University (1964-1965), University of Alberta (1965-1967), Panjab University, Chandigarh (1967-1969), and the University of Waterloo (1969-1998). After retirement, he moved to California to be close to family, and joined the faculty of the University of California San Diego as an adjunct professor of physics in 2000. The University of Waterloo honored him with both the Distinguished Teacher Award and the title Distinguished Professor Emeritus, and he is a Fellow of the American Physical Society. Raj is the author of over one-hundred published papers and two textbooks. The Theory of Relativity was first published in 1963 by Hindustan Publishing, with the second edition published by Pergamon Press, Oxford. This latter edition was republished by Dover Press in 2003. His widely used graduate physics textbook Statistical Mechanics is now in its fourth edition. It was originally published by Pergamon Press in 1974, with the second through fourth editions published by Elsevier in 1996, 2011, and 2021. Paul Beale joined Raj as coauthor of the third edition and fourth editions. Raj was nurtured in an atmosphere of Urdu language, idiom, and poetry. He published a compilation of his Urdu poems in Saihraa Saihraa, published under the pseudonym Raj Kumar Qais. The title means 'desert after desert' after the unending wanderings of Qais, the fabled lover of the Arabian damsel Laila. Raj is married to Raj Kumari Pathria. They have three children and five grandchildren.

1. The Statistical Basis of Thermodynamics
2. Elements of Ensemble Theory
3. The Canonical Ensemble
4. The Grand Canonical Ensemble
5. Formulation of Quantum Statistics
6. The Theory of Simple Gases
7. Ideal Bose Systems
8. Ideal Fermi Systems
9. Thermodynamics of the Early Universe
10. Statistical Mechanics of Interacting Systems: The Method of Cluster Expansions
11. Statistical Mechanics of Interacting Systems: The Method of Quantized Fields
12. Phase Transitions: Criticality, Universality, and Scaling
13. Phase Transitions: Exact (or Almost Exact) Results for Various Models
14. Phase Transitions: The Renormalization Group Approach
15. Fluctuations and Nonequilibrium Statistical Mechanics
16. Computer Simulations