Francis Wheeler Loomis (August 4, 1889 – February 1976), born in Parkersburg, West Virginia, was an American scientist most widely known for his contributions in the field of physics. Loomis received his PhD from Harvard University in 1917 studying the field of thermodynamics.
Loomis was a Guggenheim Fellow in 1928 studying abroad at Zürich and Göttingen, and in 1929, Loomis came to the University of Illinois at Urbana Champaign to become the head of the Department of Physics, a position he would retain until 1957. Loomis was challenged in bringing top-notch physics talent to a university in the rural Midwest. When approached by Loomis to join his staff, Isidor Isaac Rabi stated bluntly "I love subways and I hate cows." While building the department, Loomis attracted two-time Nobel recipient John Bardeen to join the staff, and had 1955 Nobel Prize winner Polykarp Kusch as a graduate student.
During World War II, Loomis was the associate head of the MIT Radiation Laboratory supporting the national defense. The interruption of the war also required Loomis to restart his building of the physics department as two-thirds of the faculty he added in the 1930s moved elsewhere due to the many defense projects related to the war.
At the University of Illinois at Urbana Champaign the main physics building was renamed the Loomis Laboratory of Physics posthumously in his honor.