Today’s physics describes nature in “empirical concepts” (concepts that are based on observation), such as coordinate space/time, wave/particle, force/field. There are coordinate-free formulations of special and general relativity (SR/GR), but there is no absolute time in SR/GR and thus no “holistic view” (view that is universal for all objects at the same instant in time). Here I show: A holistic view is required to solve the Hubble tension and 14 other mysteries. Euclidean relativity (ER) provides a holistic view by describing nature in “natural concepts” (concepts that are immanent in all objects). Proper space/time replaces coordinate space/time. “Pure energy” replaces wave/particle. I give one example where a process replaces force/field. An object’s proper space d₁, d₂, d₃ and proper time τ span natural, Euclidean spacetime (ES) d₁, d₂, d₃, d₄ with d₄ = cτ. The invariant is absolute, cosmic time θ. All energy moves through ES at the speed c. An observer’s reality is created by orthogonally projecting ES to his proper space and proper time. Information is lost in projections. This implies that ER goes beyond SR/GR and that we face mysteries if we ignore ES. I conclude: (1) ER describes the “master reality” ES. (2) SR/GR describe each observer’s reality. (3) Because of the different realities, ER does not compete with SR/GR. (4) ER provides new information that is hidden in absolute time and thus not available in SR/GR. (5) In ER, cosmic inflation, expanding space, dark energy, and non-locality are obsolete concepts. (6) ER solves 15 mysteries purely geometrically.