Joseph Henry Keenan, whom this symposium honors, died in 1977, but his groundbreaking work continues to influence the field of thermodynamics, as his colleagues, protégés and scientific descendants attest. Keenan’s efforts had practical outcomes, such as determining the properties of steam, which boosted the electric power industry. But as Ahmed Ghoniem says, Keenan’s exploration and reformulation of the laws of thermodynamics helped place this field in the center of such diverse, contemporary disciplines as the life sciences, energy, information, computation and the nanosciences. “The field has grown from a model of the heat engine to a set of fundamental principles that govern energy conversion in all forms.”

Keenan played a powerful role in MIT’s history as well, notes Susan Hockfield. In Keenan’s 40 years at the Institute, he served as a model teacher. He founded a school of thought and shaped the teaching and application of thermodynamics worldwide. His research “combined developing practical engineering tools with providing explanations of deep subtlety,” and he set a standard for academic leadership, heading the Department of Mechanical Engineering in the difficult post-Sputnik era.

To George Hatsopoulos, Keenan was “my mentor, my friend…His intuition was so unbelievably right; he always led me the right way.” Hatsopoulos shares personal anecdotes about Keenan’s rigorous thinking and precision with language, and offers two short video clips taken by Keenan’s daughter shortly before his death that reveal his method of inquiry. Hatsopoulos suggests that were Keenan alive, he would ask the symposium presenters and audience the following question: “Is entropy an intrinsic property of any system, whether microscopic or macroscopic, whether in a state of equilibrium or nonequilibrium? “