Origin of the structure of the universe from thermal fluctuations

The paper obtains the initial spectrum of potential perturbations of density arising as a result of the nonadiabatic amplification of thermal fluctuations in the early hot universe. It is shown that these perturbations could have determined the structure of the universe. This phenomenon is associated with the existence of phonons along with ordinary particles in hydrodynamic homogeneous matter with a nonzero temperature. In themselves, thermal phonons would have produced insignificantly small perturbations of density and gravitational field in cluster scales. However, owing to the conformal invariance of sound waves in a self-gravitating medium, the initial amplitude of these phonons could have been significantly amplified to a value necessary for the formation of galaxies.