  Recent investigations into the physical nature of information and fundamental
limits to information transmission have revealed questions such as the
possibility of superluminal data transfer or not; and whether reversible
computation (information processing) is feasible. In some respects these
uncertainties stem from the determination of whether information is inherent in
points of non-analyticity (discontinuities) or smoother functions. The close
relationship between information and entropy is also well known, e.g.
Brillouin's concept of negentropy (negative entropy) as a measure for
information. Since the leading edge of a step-discontinuity propagates in any
dispersive medium at the speed of light in vacuum as a precursor to the main
body of the dispersed pulse, we propose in this paper to treat information as
being intrinsic to points of non-analyticity (discontinuities). This allows us
to construct a theory addressing these dilemmas in a fashion consistent with
causality, and the fundamental laws of thermodynamics. A consequence of our
proposition is that the movement of information is always associated with the
dissipation of heat, and therefore that the concept of reversible classical
computation is not tenable.
