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

Abstract

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

arXiv comment8 pages, Essay awarded third prize in the Gravity Research Foundation essay competition 2012

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• The Causal Structure of QED in Curved Spacetime: Analyticity and the Refractive Index
• Causality and Micro-Causality in Curved Spacetime
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Cited by in corpus (10)

• The Speed of Gravity
• Black Hole Gravitational Waves in the Effective Field Theory of Gravity
• Causality in Curved Spacetimes: The Speed of Light & Gravity
• Generalized Galileon Duality
• Asymptotic states and renormalization in Lorentz-violating quantum field theory
• Superluminality, Black Holes and Effective Field Theory
• Quantum Field Theory in a Multi-Metric Background
• Constraints on the velocity of gravitational waves from NANOGrav 15-year data set
• Bimetric QED
• Superluminal Gravitational Waves