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Gravitational tidal forces acting on the virtual e+ e- cloud surrounding aphoton endow spacetime with a non-trivial refractive index. This has remarkableproperties unique to gravitational theories including superluminallow-frequency propagation, in apparent violation of causality, andamplification of the renormalized photon field, in apparent violation ofunitarity. Using the geometry of null congruences and the Penrose limit, weillustrate these phenomena and their resolution by tracing the history of aphoton as it falls into the near-singularity region of a black hole.

The Unbearable Beingness of Light, Dressing and Undressing Photons in Black Hole Spacetimes