Authors: Biliotti, Leonardo, Dipartimento di Matematica, Università di Parma, Via G. Usberti, 53/A 43100, Parma, Italy (leonardo.biliotti@unipr.it), and Javaloyes, Miguel Angel, Departamento de Geometrí a y Topologíca, Universidad de Granada, Campus Fuentenueva S/N, 18071, Granada, Spain (majava@ugr.es)
t-periodic light rays in conformally stationary spacetimes via Finsler geometry,pp. 127-146.
ABSTRACT. In this paper we prove several multiplicity results of t-periodic light rays in conformally stationary spacetimes using the Fermat metric and the extensions of the classical theorems of Gromoll-Meyer and Bangert-Hingston to Finsler manifolds. Moreover, we exhibit some stationary spacetimes with a finite number of t-periodic light rays and compute a lower bound for the period of the light rays when the flag curvature of the Fermat metric is η-pinched.