Gravitation, holographic principle, and extra dimensions
  Within the context of Newton's theory of gravitation, restricted to
point-like test particles and central bodies, stable circular orbits in
ordinary space are related to stable circular paths on a massless, unmovable,
undeformable vortex-like surface, under the action of a tidal gravitational
field along the symmetry axis. An interpretation is made in the light of a
holographic principle, in the sense that motions in ordinary space are
connected with motions on a selected surface and vice versa. Then ordinary
space is conceived as a 3-hypersurface bounding a $n$-hypervolume where
gravitation takes origin, within a $n$-hyperspace. The extension of the
holographic principle to extra dimensions implies the existence of a minimum
distance where test particles may still be considered as distinct from the
central body. Below that threshold, it is inferred test particles lose theirs
individuality and "glue" to the central body via unification of the four known
interactions and, in addition, (i) particles can no longer be conceived as
point-like but e.g., strings or membranes, and (ii) quantum effects are
dominant and matter turns back to a pre-big bang state. A more detailed
formulation including noncircular motions within the context of general
relativity, together with further knowledge on neutron stars, quark stars and
black holes, would provide further insight on the formulation of quantum
gravity.
