Konwersatorium im. Leopolda Infelda

The fluctuations of spacetime geometries at finite temperature are evaluated within the linearized theory of gravity. These fluctuations will be described by the probability distribution of various configurations of the gravitational field. The gravitational field configurations are described by the linearized Riemann-Weyl tensor. The probability distribution has a foam-like structure, as intuitively argued by Wheeler. Prevailing configurations are those with the large changes of geometry at nearby points. Striking differences are found between the fluctuations of the electromagnetic field and the gravitational field