The main results of the scientific activity of Sergey Siparov are given in the publications. In general they are characterized as follows. At the beginning of scientific activity Sergey dealt both with theoretical and experimental studies. In particular, the work in AARI and on the drifting stations “North Pole” was devoted to theoretical and experimental study of strength and fracture of viscoelastic bodies (sea ice) when exposed to a moving load. Ph.D. thesis and work in Lensoveta Inst. were devoted to the solution of the inverse Stefan problem for the heat and mass transfer in porous media. The results of mathematical investigation of non-streamlined bodies’ aerodynamics performed in ACA were tested under field conditions in Western Siberia. The data for the constructed mathematical model describing the relationship of the magnetic field on the surface of the volcano with volcanic activity were collected on an expedition to Elbrus. Later the research interests of Sergey shifted to the area of statistical physics where the structural phase transitions in fullerenes and nanotubes were studied, and then to the field of quantum optics, where the effect of optical-mechanical parametric resonance was predicted and theoretically investigated. Conditions for the latter are found in outer space, where it becomes relativistic optical-metrical parametric resonance (OMPR). This led to the development of the theory and experimental method for the detection of gravitational waves in the zero-order effect. Later, the analysis of the problems arising in general relativity on a cosmological scale led to the development of the equivalence theory (or anisotropic geometrodynamics). To test it, one can use the results of statistical processing of observation of OMPR. Currently, the first encouraging observations of OMPR were made in Pushchino Radio-astronomical Observatory of RAS, and the work on the equivalence theory continues.