Although Theodorsen's life work was in aerodynamics, and he published numerous books and papers in that field, he had other interests. In particular, he wrote a paper, "Relativity and Classical Physics" which sought to show that the results of Albert Einstein's theory of general relativity could be obtained without resorting to curved space-time by a modification of Newton's law of universal gravitation. The paper presents "a successful transformation of the theory of relativity into classical physics... The mathematical entities of the Einstein development have been redefined into rational physical quantities and rearranged in an organized classical framework. Einstein's space-time has been eliminated and replaced by cognitive time." It was published in the Proceedings of the DKNVS Theodorsen Colloquium and on two later occasions.Proceedings of the Theodorsen Colloquium 1976. (Det Kongelige norske videnskabers selskab). Trondheim: Universitetsforlaget, 1977) "Relativity and Classical Physics". Galilean Electrodynamics, July/August 1995.
