In parallel with the work in the hospital, he continued his self-education, so that in 1944 he passed exams for the entire course of the school and started to study at the Physical Faculty of the Leningrad University.

In 1953 Yuri Yappa earned his PhD (Russian: кандидат наук) degree with a thesis on the relativistic theory of elementary particles.

[2] In 1954–1956, he led a group of theoreticians at the Institute of Nuclear Problems of the Soviet Academy of Sciences in Dubna (Moscow Region).

His group worked on the theory of elementary particles and provided theoretical explanation of experimental results on proton scattering.

Yuri Yappa led a number of theoretical courses in the Leningrad/St.-Petersburg University, including his well-known courses of General Relativity, which was passed to him by Vladimir Fock in 1958, and of classical electrodynamics, which served the base of his graduate book (coauthored by Viktor Novozhilov) Electrodynamics,[6] whose revised edition was published and republished in English.