Rest frames for tachyons and photons

A formalism is developed which admits particles faster than light and reference frames faster than light and as fast as light. It is fully consistent with the physical principles of special relativity. The necessity of introducing imaginary quantities does not arise. It does not encounter any difficulties with the principle of causality if it is reasonably interpreted.Dedicated to Prof. E. C. G. Sudarshan, in honor of his receipt of the Padmabushan Award.