Mass, Space, Time, and Gravity are the four basic metaphysical assumptions for the reality of physical measurement. They have no separate measurable definitions outside of these two equations. Their separate values can be measured but only as a part of the whole. This a unified principle of measurement for atoms, photons, gravity, and cosmology. This physical principle of the cosmos is not meant to be a physics “theory” of matter and gravity. It is merely measurements of absolute linear and angular momentum and contains no unmeasured metaphysical assumptions such as spacetime, aethers, or gravitational “fields”.