The Net in the River - A Hydro-Mechanical Framework for Spacetime, Gravity and The Dark Sector

The Net in the River, models our universe as an elastic membrane (the "net") stretched across a supersonic flow (the "river") in a four-dimensional space. From this single picture and eleven stated assumptions, it derives results that usually require separate theories: Flat space, explained. The universe sits on a horosphere, a surface that is flat from within. Spatial flatness follows from geometry alone, without requiring an inflationary epoch. Einstein's equations, derived. General relativity emerges as a mathematical theorem (via Lovelock's theorem) rather than an assumption. Newton's constant becomes a physical property: the net's stiffness. Gravity's strength, protected. The quantum corrections that normally destabilise gravity cancel exactly across the Standard Model, 48 against 48. The cancellation works only with right-handed neutrinos, which the theory requires independently. Dark energy, identified. Dark energy is the net's tension, matching the observed value. The theory makes a sharp, testable claim: dark energy can never grow stronger over time, provided one stated condition on the river's flow holds. Neutrino masses, predicted. From two measured quantities, the theory fixes all three neutrino masses, a total of 0.0599 ± 0.0004 eV, in normal ordering. Dark matter, unified. Dark matter is vibrations of the net itself, with a proven trade-off: either these particles or a tabletop fifth force, never both. Black holes, resolved. Black holes are tears in the net. Their radiation matches Einstein's theory to one part in 10⁵⁸, and their information exits into the river. Its merits. The theory uses only two fitted parameters. It turns long-standing puzzles into specific calculations. It has corrected its own errors in public. Above all, it is falsifiable: DESI, Euclid, JUNO and LEGEND will test its predictions within a decade. Few frameworks reach this far on so little. Fewer still are willing to be proven wrong this quickly.