Proper velocity Proper velocity In relativity, proper velocity, also known as celerity, is an alternative to velocity for measuring motion. Whereas velocity relative to an observer is distance per unit time where both distance and time are measured by the observer, proper velocity relative to an observer divides observer-measured distance by the time elapsed on the clocks of the traveling object. Proper velocity equals velocity at low speeds. Proper velocity at high speeds, moreover, retains many of the properties that velocity loses in relativity compared with Newtonian theory. For example, proper velocity equals momentum per unit mass at any speed, and therefore
C. N. Yang Institute for Theoretical Physics C. N. Yang Institute for Theoretical Physics The C. N. Yang Institute of Theoretical Physics (YITP) is a research center at Stony Brook University. In 1965, it was the vision of then University President J.S. Toll and Physics Department chair T.A. Pond to create an institute for theoretical physics and invite the famous physicist Chen Ning Yang from Institute for Advanced Study to serve as its director with the Albert Einstein Professorship of Physics. While the center is often referred to as "YITP", this can be confusing as YITP also stands for the Yukawa Institute for Theoretical Physics in Japan.