  We show that the concept of entropy and the dynamics of gravitation provide
the linchpin in a unified scheme to understand the physics of black hole
computers, space-time foam, dark energy, dark matter and the phenomenon of
turbulence. We use three different methods to estimate the foaminess of
space-time, which, in turn, provides a back-door way to derive the
Bekenstein-Hawking formula for black hole entropy and the holographic
principle. Generalizing the discussion for a static space-time region to the
cosmos, we find a component of dark energy (resembling an effective positive
cosmological constant of the correct magnitude) in the current epoch of the
universe. The conjunction of entropy and gravitation is shown to give rise to a
phenomenological model of dark matter, revealing the natural emergence, in
galactic and cluster dynamics, of a critical acceleration parameter related to
the cosmological constant; the resulting mass profiles are consistent with
observations. Unlike ordinary matter, the quanta of the dark sector are shown
to obey infinite statistics. This property of dark matter may lead to some
non-particle phenomenology, and may explain why dark matter particles have not
been detected in dark matter search experiments. We also show that there are
deep similarities between the problem of "quantum gravity" (more specifically,
the holographic space-time foam) and turbulence.
