A unified conceptual formulation of space, time, and gravity is presented through thebathtub–universe analogy. The central idea: time is a physical flow and gravity isits local manifestation. Water represents the universal medium; drains, the mass cores(stars, black holes); the water column above, the future. The analogy reproduces relativisticphenomena (time dilation, light bending, horizons, waves) and further provides a natural andcoherent reading of three cosmological pillars: (i) the CMB as fossil foam of the first drain,(ii) dark matter as a hydrodynamic effect of vorticity halos (not substance), and (iii) darkenergy as recycled drained flow accelerating the rise of the present. We include qualitativelyfalsifiable predictions without introducing hard quantum mechanics. For the analogy we usea 3D scheme, where the horizontal axes represent a 2D space and the vertical axis representsthe universal temporal dimension. Special clarification: This analogy is metaphorical anddoes not suggest that the universe is literally made of water and drains.
Marcos Delfino Lopez Alvarez (Fri,) studied this question.