Entropy of massive quantum fields in de Sitter space–time

Using the quantum states or Hilbert spaces for the quantum field theory in de Sitter ambient space formalism the entropy of the massive quantum field theory is calculated. In this formalism, the homogeneous spaces which are used for construction of the unitary irreducible representation of de Sitter group are compact. The unique feature of this homogeneous space is that by imposing certain physical conditions its total number of quantum one-particle states, N1−pN1−p, becomes finite although the Hilbert space has infinite dimensions. N1−pN1−p is de Sitter invariant and a continuous function of the Hubble constant HH and the eigenvalue of the Casimir operators of de Sitter group. The entropy of the quantum fields is finite and invariant for all inertial observers on de Sitter hyperboloid.