Variable speed of light find out that it doesn't go only at the speed of light! It may surprise you that there is an amplitude for a photon to go at speeds faster or slower than the conventional speed, "c"." These virtual photons, however, do not violate causality or special relativity, as they are not directly observable and information cannot be transmitted acausally in the theory. Feynman diagrams and virtual photons are usually interpreted not as a physical picture of what is taking place, but rather as a convenient calculation tool (which, in some cases, happen to involve faster-than-light velocity vectors). In 1937, Paul
One-way speed of light speed of light independently of any clock synchronisation convention, but they have all been shown to actually measure the two-way speed, because they are consistent with generalized Lorentz transformations including synchronizations with different one-way speeds on the basis of isotropic two-way speed of light (see sections the one-way speed and generalized Lorentz transformations). These experiments also confirm agreement between clock synchronization by slow transport and Einstein synchronization. Even though some authors argued that this is sufficient to demonstrate the isotropy of the one-way speed of light, it has been shown that such experiments cannot, in any meaningful way, measure the