Vacuum and gravitation

It has been hypothesized that there exists a gravitational vacuum polarization. It takes into account the fundamental principles of two-signs gravitation: the main component of the space medium is the vacuum, it is neutral in the electrical and gravitational sense, there is a difference of signs of gravitational charges of particles and anti-particles. It is shown that if the hypothesis is true, then the gravitation is not only the attractive forces, but the repulsion forces also. The hypothesis of gravitational vacuum polarization is alternative to the hypothesis on the existence of the dark matter.