I know that the speed of light has been measured with great precision and used successfully in many calculations. I just wonder why this specific speed. What is the deep reason? I am aware that if the strength of the fundamental forces is not what they are, we Earthlings would not be here; we would not exist. Is there a link between these forces and c that imposes the speed limit to c? I have heard of the Tachyon whose lowest speed is c, but has never been detected, so I tend to ignore it. As a product of the above questions: What would happen to the universe if the speed of c is less or more than ~186,282 mi/s in the vacuum? I would greatly appreciate your answers.