Graviton instability and graviton condensation

When multiple real gravitons are present, the quantum gravitational effect, caused by the exchange of virtual gravitons among them, leads to instability in the real gravitons. As a result of this instability, the condensation of real gravitons occurs. For a single isolated real graviton, which is not a bound state of multiple gravitons, the quantum gravitational effect discussed in this paper does not occur, and the classical limit of gravity is correctly reproduced as a soft limit. The mean-field analysis method is used to analyze the graviton condensate. Applications of graviton condensation to the atomic nucleus and the confinement of quarks and gluons are also discussed.