How to use in-sentence of “Energy density”:
+ The suggested mechanism was “progressive” length contraction and time dilation—a consequence of the local energy density within 3D space—establishing a progressive tension within a rigid object, relieving its tension by moving toward the location of greatest energy density.
+ By converging space and time and presuming both relative to the energy density in the vicinity, and by setting the only “constant” or absolute as not even mass but as light speed in a vacuum, general relativity revealed the natural world’s previously unimagined balance and symmetry.
+ Special relativity would apply when the energy density across 3D space is uniform, and so the gravitational field is scaled uniformly from location to location, why an object experiences no acceleration and thus no gravitation.
+ As the Universe expands, the energy density of the electromagnetic radiation decreases more quickly than does that of matter, since the energy of a photon decreases with its wavelength.
+ Thus, although the energy density of the Universe is now dominated by matter, it was once dominated by radiation; poetically speaking, all was light.
