  We consider a recent generalisation by Bousso of an earlier holography
proposal by Fischler and Susskind. We demonstrate that in general inhomogeneous
universes such a proposal would involve extremely complicated - possibly
fractal - light sheets. Furthermore, in general such a light sheet cannot be
known a priori on the basis of theory and moreover, the evolution of the
universe makes it clear that in general such bounds cannot remain invariant
under time reversal and will change with epoch.
  We propose a modified version of this proposal in which the light sheets end
on the boundary of the past, and hence avoid contact with the caustics. In this
way the resulting light sheets and projections can be made much simpler. We
discuss the question of operational definability of these sheets within the
context of both proposals and conclude that in both cases the theoretical
existence of such sheets must be clearly distinguished from their complexity
and the difficulty of their construction in practice. This puts into
perspective the likely practical difficulties one would face in applying the
holographic principle to the real cosmos. These issues may also be of relevance
in debates regarding the applications of the holographic principle to other
settings such as string theory.
