In memory of Andrei Anatol'evich Grib

Wheeler, and others and were able to get acquainted with new achievements of science.At the postgraduate school, A A Grib analyzed the idea of spontaneous symmetry breaking, vacuum state noninvariance, the Coleman and Goldstone theorems, and the possible existence of the Higgs boson.As a matter of fact, Andrei Anatol'evich worked on his candidate thesis independently and defended it successfully in 1969.The further development of physics, in particular, the formulation of the WeinbergSalam theory, quantum chromodynamics, the discovery of W-and Z-bosons, as well as the Higgs boson, confirmed that Andrei Anatol'evich was right to have chosen this area of science.The results of his work on spontaneous symmetry breaking and related problems were summarized in his review published in the journal PhysicsUspekhi (Uspekhi Fizicheskikh Nauk) [1] and in book [2].Another field of physics to which A A Grib made an outstanding contribution is the theory of particle production from a vacuum in the gravitational field of the expanding Universe.In two pioneering studies [3,4] published jointly with S G Mamayev, he used the Hamiltonian diagonalization method to obtain for the first time a finite value of the density of the number of particleantiparticle pairs created in the early Friedmann Universe.These results, obtained for the case of a scalar field, were later extended to the cases of spinor and vector particles.The proposed method proved to be very