The shadow of light: Challenging classical and quantum electrodynamics

We review some optical experiments, carried out in the last decade, which evidence an anomalous behavior of photon systems. Their results are apparently at variance with both standard quantum mechanics (in the Copenhagen interpretation) and usual (classical and quantum) electrodynamics. In particular, they can be interpreted as a virtual interference involving the pilot waves associated to photons (according to Bohmian quantum mechanics). The anomalous effects exhibit a threshold behavior in energy and space, which agrees with results obtained on the electromagnetic breakdown of local Lorentz invariance. A possible connection between these seemingly unrelated implications of the observed phenomenon can be set by assuming that the pilot wave of a photon is a deformation of spacetime ("shadow of light").