sentences:  He also discussed the hierarchy of vortices (Kolmogorov).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.