Llewellyn Hilleth Thomas (born 21.10.1903) was an American theoretical physicist and a member of the National Academy of Sciences (1958). He was born in London. He graduated from the University of Cambridge (1924). In 1929-43 and in 1945-46 he was professor at the University of Ohio, in 1946-68 professor at Columbia University, and in 1968 —76 at the University of North Carolina.
His research concerned atomic physics (the passage of particles through matter, the distribution of electrons in atoms and molecules), relativity, astrophysics, the theory of liquids, the study of nuclear, atomic and molecular structures, the theory of accelerators and computational methods. In 1927 he proposed an approximate scheme for describing and calculating the ground state of many-electron atoms, which was developed in 1928 by E. Fermi (the Thomas — Fermi model of the atom). He obtained the formula for the spin — orbit interaction energy in a central field.