  Very simple experiments based on an analogy between two theories (gravitation
and capillarity) allowed us to construct a two dimension space toy-universe
composed of the surface of a three-dimensional water tank with floating soap
bubbles and bubble clusters.This very simple approach leads to a surprising
description of our universe with, in particular, the existence of a fourth
dimension inaccessible to us. Such a 4th macroscopic dimension suggests the
existence of a huge 4 D tank of heavy fluid (analogous to our 3 D water tank)
sitting below our three dimensional universe (which is the surface of the main
4 dimensions universe). Among other consequences:an original interpretation of
the event horizon of black holes or a simple answer to the problem of missing
dark matter.
