Scharnhorst effect

The Scharnhorst Effect is a hypothetical phenomenon in which light signals between two parallel conducting plates in vacuum propagate faster than light. The effect was predicted by Klaus Scharnhorst of the Humboldt University in Berlin and Gabriel Barton of the University of Sussex. They showed using quantum electrodynamics that the effective refractive index at low frequencies, in the space between the plates is less than 1 ( which in itself is not faster than light in the signal transmission implies ). They could not show that the wavefront exceeds the speed of light c ( which would imply signaling faster than light ), but that this would be plausible.

Explanation

Due to the Heisenberg uncertainty principle is a space that appears empty at first, in reality filled with virtual particles. This is the phenomenon of vacuum fluctuation. While a photon travels through the vacuum, it interacts with the virtual particles and it can sometimes pairing occur. In this case, a particle and its antiparticle from the energy of the photon is produced. For example, arise from a photon of suitable energy an electron -positron pair annihilates quickly, since it is not stable. While the energy of the photon is in a particle-antiparticle pair, the energy can not travel at light speed, so the speed of light is reduced in a vacuum.

A prediction that follows from this assertion is that the speed of light, a photon is increased in a vacuum, as it propagates in the area between two Casimir plates. Between the two plates, only certain virtual particles are allowed. Excluded virtual particles have too large a De Broglie wavelength compared to the distance between the two plates. Therefore, the effective density of the virtual particles in the region between the plates is lower than outside the plates. Therefore, the photon, which propagates between the plates interact with fewer virtual particles and therefore spread faster than a photon outside the plates. The effect would increase the velocity of propagation of a photon. The closer the plates are together, the lower is the virtual particle density, and the higher is the speed of light.

The predicted effect, however, is minimal. A photon propagating between two plates that have a micrometer distance from each other would increase its speed by only 10 - 36c. This change in the speed of light is not measurable with current technology.