Soap Bubbles on the Surface of a Liquid: A Playful Universe in 3+1 Dimensions, a Real Universe in 4+1 Dimensions

Very simple experiments based on an analogy between two theories __ gravitation and capillarity __ allowed us to construct a 2-dimensional-space toy-universe (U2D) composed of the surface of a 3D water tank with floating soap bubbles and bubble clusters. The experiments performed with or without a “black hole” suggest that our visible universe (U3D) is composed of the 3D “surface” of a 4D universe essentially filled with a heavy fluid that, interestingly, possesses all the properties presently attributed to “dark matter”. The observations of this U2D and their implications for the structure and evolution of our U3D are discussed openly without preconceptions, not to say naively. This analogy led us to propose a scenario reproducing several observations made in our U3D. It would also allow us to schematically investigate the evolution of portions of our visible universe (stars, black holes, galaxies) at easily available timescales (seconds, to days) in contrast with the billions of years required for direct observations. More basically, it suggests that the 4D volume of our universe, which is inaccessible to us, constitutes a huge tank of heavy fluid sitting “below” our 3D surface universe and this has several consequences such as an original interpretation of the event horizon of black holes or a simple answer to the problem of missing dark matter.