Nimtz G., Stahlhofen A. Macroscopic violation of special relativity. — 5 Aug 2007, arXiv: 0708.0681 [quant-ph]

Feynman, one of the founders of Quantum Electrodynamics (QED) introduced virtual particles in his diagrams as intermediate states of an interaction process. Such virtual particles are not observable. However, from the theoretical point of view, they represent necessary intermediate states between observable real states. Such virtual particles were introduced for describing the interaction process between an electron and a positron and for much more complicated interaction processes. Other candidates for virtual photons are evanescent modes in optics. Evanescent modes have a purely imaginary wave number and represent the mathematical analogy of the tunneling solutions of the Schrödinger equation. Evanescent modes are present in the forbidden frequency bands of a photonic lattice and in undersized wave guides for instance. The most prominent example of the occurrence of evanescent modes is frustrated total internal reflection (FTIR) at double prisms. In 1949 Sommerfeld pointed out that this optical phenomenon represents the analogy of quantum mechanical tunneling. The evanescent modes (i.e. tunneling) lie outside the bounds of the special theory of relativity.

arXiv:0708.0681 [quant-ph]