  People need a model to study tachyons whose prediction can be tested easily.
The dispersion relation w^2=k^2C^2-a^2C^2 of a low-frequency electromagnetic
field in good conductors is equivalent to the energy-momentum equation
E^2=p^2C^2-m^2C^4 of a tachyon where the proportionality coefficient is h^2. An
experiment in 1980s to measure the phase velocity Vp [1] can be regarded as an
indirect evidence of the superluminal velocity V>>c of those photons just
equals the rate of energy flow S/w of the field.Instability of the tachyonic
field corresponds to the Joule heat. To detect the speed of energy is difficult
and we plan to modulate signals to observe the information velocity (speed of
points of non-analyticity)[2].
