From Dirac theories in curved space-times to a Variation of Dirac's   large-number hypothesis
  An overview is given of recent developments in the field of Dirac equations generalized to curved space-times. An illustrative discussion is provided. We conclude with a variation of Dirac's large-number hypothesis which relates a number of physical quantities on cosmological scales. 
U. D. Jentschura
physics.gen-ph gr-qc hep-ph