Frank Clark Hoyt was an American physicist, regarded as one of the first theoretical physicists to come from the USA in the period that quantum mechanics was being developed.

Carl Henry Eckart was an American physicist, physical oceanographer, geophysicist, and administrator. He co-developed the Wigner–Eckart theorem and is also known for the Eckart conditions in quantum mechanics, the Eckart–Young theorem in linear algebra., and his work on non-equilibrium thermodynamics and continuum mechanics, including a relativistic treatment