In 1966 Ma joined the University of California, San Diego physics department as an assistant researcher in Keith Brueckner's research group. He was promoted to faculty status in 1967 and remained with the physics department until his death in 1983.
Critical phenomena are highly unusual.
Many substances have phase transitions that are commonly observable, such as the transition of water to steam. Critical phenomena involve phase transitions that, under certain circumstances, exhibit unique characteristics. Water, for example, can appear as a milky and turgid substance, given the presence of specific values of critical exponents. Five critical exponents, or factors, give rise to the diversity of critical phenomena observed by physicists in such areas as fluid and ferromagnetic systems. The study of critical phenomena has focused on determining the quantitative value of these factors.