I'm trying to wrap my head around how C could be constant and time can change depending on perspective. I wasn't getting anywhere until I starting thinking of light as water and then I started feeling like I understood it a little better but tell me if this is accurate at all. If running water represents light then suppose the universe is like a lake. The lake is full of varying currents running this way and that. There are rocks in some areas causing the water to move faster and areas where the banks narrow causing the water to speed up. Some inlets where the water swirls in and then seems to stagnate. Big open bodies where the water flows at the same speed for long stretches and some whirlpools swirling around. Then there are other forces like wind and undercurrents etc. We're like fish. While swimming around we encounter differen't currents but we adapt. If we're swimming along in a stagnant pool and then find ourselves suddenly in a swirling current beside a boulder we have to exert more energy to keep up the same speed. So our heart beats faster and metabolism speeds up along with our brain activity but this actually makes it seem as though the same amount of time is going by since our biological functions have sped up. The water is going twice as fast but our body and mind have sped up to meet the challenge. By our perspective the same amount of time has passed. Once we get out of the fast moving water everything slows down in perfect symetry to meet the new speed speed of the current. If I'm swimming in slow moving water there could be a fish beside me caught in a faster current but he's moving faster and seems to be swimming alongside me. Does that make any sense?