He also lectured in MGU (1930 –1932 and 1934–1938), in the Gorky State University (1932–1934 and 1945–1947) and in the and at the Moscow Institute of Physics and Technology (1947–1978).
Rytov became an expert on the theory of thermal electromagnetic radiation based on the generalization of the fluctuation-dissipation theorem.
[9][10][11] Rytov's work would later be summarized in a series of books Principles of Radiophysics, co-authored with Yurii A. Kravtsov and Valeryan I. Tatarsky on radiophysics (Russian term for the theory of linear and nonlinear wave phenomena), where he discussed a series of topics related on fluctuation phenomena in electronic systems random fields and random propagation waves.
[12] Rytov theory would be simplified by Dirk Polder and Michael van Hove in 1971 to describe thermal radiation between closely spaced bodies.
This led to the development of near-field radiative heat transfer theory, to which Rytov also contributed later.