"radiation transmits inertia between emitting and absorbing bodies" Albert Einstein "The equation E=mc^2 connects intangibility and tangibility and by making them equivalent, joins them as one. Energy and mass are different and it is the speed of light that brings them together." Einstein 1905 The Standard of Excellence John S. Rigden Rather than saying that the speed of light is constant, though it is generally so, it is more accurate to say that the speed of light is the speed limit for the universe. In fact, nothing is permitted to go even that fast, except light itself. If time and gravity, as I have said, are how we feel the pre-time force which is the luminiferous ether (that Faraday and Maxwell quite properly believed exists), then light is that matter with the least mass. It is quite possibly the direct precursor to the smallest quantum level particle destined to become subatomic particles, then atoms, then more complex structures. A local disturbance in th...