Superluminal motion in (semi)classical relativity
The possibility is discussed of superluminal motion of non-tachyonic (i.e. moving with the instantaneous speed v<c) bodies within general relativity. It is shown that in some occasions quantum field theory apparently prohibits such motion, but not - to all appearance - in the general case.
We study the photorefractive self-action of light beams within an iron-doped planar optical waveguide in lithium niobate biased by external electric field, to find the conditions for the formation of quasisteady-state screening-photovoltaic spatial solitons. Their formation is expected to take much shorter time compared with the steady-state photovoltaic solitons.