The two 3D quantities of 4D hypervolume are distance^3 (space) and time*distance^2 (energy). Energy moves through space. Time is the dimension that bounds, not extends, three-dimensional space. Unit hypervolume is the internal product of time and space, but it is also the product of energy and distance. The speed of light is the one and only dimensional equivalent between space and time. Energy density is the 4th-dimensional slope of space. Just as Planck’s constant is the four-dimensional quantization of photons, elementary charge is the four-dimensional quantization of particles. Photons are the encapsulation of time by space; particle fields are the encapsulation of space by time.