Special/general relativity (SR/GR) work for all 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 in ES. All action in ES is due to an absolute, external parameter θ. Every object experiences two orthogonal projections from ES as space and time: The axis of its current 4D motion is its proper time τ. Three orthogonal axes are its 3D space x1, x2, x3. Observing is synonymous with projecting objects from ES onto an observer’s physical reality, which is a 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. ER predicts the same relativistic effects as SR/GR, but gravity is Newtonian. Action at a distance is not an issue: Information is instantaneous in timeless ES. Only in physical realities does the time coordinate cause a delay. Presumably, gravity is carried by gravitons and manifests itself in τ-MS as gravitational waves. ER does not require curved spacetime, cosmic inflation, expanding space, dark energy, and non-locality. Nonetheless, ER predicts time’s arrow, galactic motion, the Hubble tension, entanglement, and more. We propose using ER in cosmology and quantum mechanics. Is ER the key to unifying physics?