Scharnhorst effect

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

Explanation

Due to Heisenberg's uncertainty principle , a space that initially appears empty is actually filled with virtual particles . This is the phenomenon of vacuum fluctuation . While a photon moves through the vacuum, it interacts with the virtual particles and pairing can occur under certain circumstances . This creates a particle and its antiparticle from the energy of the photon. For example, an electron-positron pair can arise from a photon of suitable energy, which quickly annihilates again because it is not stable. While the energy of the photon is in a particle-antiparticle pair, the energy cannot travel at the speed of light, so the speed of light is reduced in a vacuum.

One prediction that follows from this claim is that the speed of light of a photon in a vacuum is increased if it propagates in the area between two Casimir plates . Only certain virtual particles are allowed between the two plates. The excluded virtual particles have too large a De Broglie wavelength compared to the distance between the two plates. Therefore, the effective density of virtual particles in the area between the plates is lower than outside the plates. Therefore, the photon that propagates between the plates will interact with fewer virtual particles and will therefore propagate faster than a photon outside the plates. The effect would increase the speed of propagation of a photon. The closer the plates are to each other, the lower the virtual particle density and the higher the speed of light.

However, the predicted effect is minimal. A photon propagating between two plates that are one micrometer apart would only increase its speed by 10 −36 c . This change in the speed of light cannot be measured with today's technology.

Individual evidence

  1. ↑ The original work is: G. Barton, K. Scharnhorst: QED between parallel mirrors: light signals faster than c, or amplified by the vacuum . In: Journal of Physics A . 26, No. 8, 1993, p. 2037. bibcode : 1993JPhA ... 26.2037B . doi : 10.1088 / 0305-4470 / 26/8/024 . A more recent paper is: K. Scharnhorst: The velocities of light in modified QED vacua . In: Annals of Physics . 7, No. 7-8, 1998, pp. 700-709. arxiv : hep-th / 9810221 . bibcode : 1998AnP ... 510..700S . doi : 10.1002 / (SICI) 1521-3889 (199812) 7: 7/8 <700 :: AID-ANDP700> 3.0.CO; 2-K .
  2. ↑ M. Chown: Can photons travel 'faster than light'? . In: New Scientist . 126, No. 1711, 1990, p. 32. bibcode : 1990NewSc.126 ... 32B .
  3. ^ JG Cramer: FTL Photons . In: Analog Science Fiction & Fact Magazine . December 1990. Retrieved November 26, 2009.
  4. ^ Secret of the vacuum: Speedier light . In: Science News . 137, No. 19, 1990, p. 303.