One Theory Fits All—from the Very Distant to the Very Small

Special and general relativity (SR/GR) work for observers, but they do not provide diagrams of nature that work for all observers. This is because they do not describe nature as an absolute manifold, where all action is due to an absolute parameter. We show: Euclidean relativity (ER) achieves precisely that. It describes a mathematical Master Reality, which is absolute 4D Euclidean space (ES). All objects move through ES at the dimensionless speed C. There is no time coordinate in ES. All action in ES is due to an absolute, external evolution parameter θ. In addition, ER describes an observer’s physical reality. He experiences two projections from ES as space and time: The axis of his current 4D motion is his proper time τ. Three orthogonal axes make up his 3D space x1, x2, x3. Without gravity, his reality is the Minkowskian reassembly of his axes x1, x2, x3, τ. In this τ-based Minkowskian spacetime (τ-MS), τ is the time coordinate and θ converts to parameter time ϑ. Minkowski spacetime and τ-MS are mathematically identical. Thus, ER retains the SR formalism. ER also retains the GR formalism, but only locally (τ defines a specific physical reference frame). The Einstein field equations hold true in physical realities, but not in ES. ER reproduces both the Lorentz factor and gravitational time dilation. ER rejects cosmic inflation, expanding space, dark energy, and non-locality. Nevertheless, ER predicts time’s arrow, galactic motion, the Hubble tension, and entanglement. Thus, ER significantly improves cosmology and quantum mechanics. We conclude: ER is indispensable for unifying physics.