The constancy of the speed of light is paradoxical The postulate that the speed of light is the same in any inertial frame leads immediately to a paradox, described below. This is Cerulean. Cerulean named fashion colour of the moment . Flash Vermilion emits a flash of light.
Vermilion thinks that the light moves outward at the same speed in all directions.
So Vermilion thinks that she is at the centre of the expanding sphere of light. Again, Vermilion emits a flash of light. Vermilion thinks she is at the centre of the expanding sphere of light, as before. But, says special relativity, Cerulean also thinks that the light moves outward at the same speed in all directions from him. So Cerulean should be at the centre of the expanding light sphere too.