Einstein deduced the speed of light from how our world behaves but why is it that speed and no other? Saying a photon goes at light speed because it has no mass doesn’t explain why there is a maximum speed at all. Why not the speed of light plus one? What makes the speed of light a maximum for our universe? The current view of physics, after almost a century of consideration, is that:
“… the speed of light is a constant because it just is, and because light is not made of anything simpler.” (Laughlin, 2005) p15
Yet “because it just is” has never been a very satisfactory answer in science. In this model, light moves at a fixed speed because the quantum network refreshes at a finite rate, just as our computers do. But while a 5GHz computer runs 5,000,000,000 cycles per second the quantum network cycles nearly 1045 times a second. The processing we call light is passed from one node of space to the next each cycle, so its speed depends on the quantum network cycle rate not the photon itself. What we call the speed of light is really the speed of space.
Actually, the speed of light isn’t constant as light slows down in water. When light moves in water we say the medium is water and when it moves in glass we say the medium is glass but when it moves in a vacuum we call it a wave of nothing! In quantum realism, whether it travels through glass, water or space, the medium is always the quantum network. Light slows down in water not because water is its medium but because the quantum network slows down when it has to process matter as well as transmit light. Light slows down in water for the same reason that a computer game slows down under load. Light also slows down in a gravitational field for that reason.
The quantum network cycles at different rates depending on load but still keeps photons in a strict sequence one behind the other, like the baggage cars of a train driven by the same engine. Each node passes on the photon it has then accepts another in the line. If the engine slows down under load, say near a massive star, photons go slower but still keep the same order, e.g. in gravity lensing, photons from a cosmic event arrive on earth at different times by different paths but are still in lock-step order. This maintains causality, as if one photon could overtake another one might see an object arrive before it left! Causality requires photons to stay in sequence and the quantum grid rigorously maintains this.