The finite entropy of de Sitter space suggests that in a theory of quantum gravity there are only finitely many states. It has been argued that in this case there is no action of the de Sitter group consistent with unitarity. In this note we propose a way out of this if we give up the requirement of having a hermitian Hamiltonian. We argue that some of the generators of the de Sitter group act in a novel way, namely by mixing in- and out-states. In this way it is possible to have a unitary S-matrix that is finite-dimensional and, moreover, de Sitter-invariant.
|Title of host publication
|The Tenth Marcel Grossmann Meeting
|Subtitle of host publication
|On Recent Developments in Theoretical and Experimental General Relativity, Gravitation and Relativistic Field Theories
|World Scientific Publishing Co.
|Number of pages
|Published - Jan 1 2006
ASJC Scopus subject areas
- General Physics and Astronomy