Anti-Shielding Effect and Negative Temperature in Instantaneously Reversed Electric Fields and Left-Handed Media

The connections between the anti-shielding effect, negative absolute temperature and superluminal light propagation in instantaneously reversed electric fields and in left-handed media are considered in the present paper. An instantaneous inversion of the exterior electric field may put the electric dipoles into a state of negative absolute temperature and therefore give rise to a negative effective mass term of the electromagnetic field (i.e., the electromagnetic field propagating inside the negative-temperature medium will acquire an imaginary rest mass), which is said to result in the potential superluminality effect of light propagation in this anti-shielding dielectric. In left-handed media, such phenomena may also arise.