How would the Universe evolve under differing values of c? c being the speed 3 x 10^8 m/s as defined, being the speed electromagnetic, and other massless forces propogate. I'm interested in scenarios where c varies relative to the other constants of nature, I'm wondering if or how the anthropic principle can be applied to our observed value of c. I've tried starting with considering how the universe would evolve if c=0, and a simple E=mc^2 indicates no energy and mass and a non-existent universe. I'm wondering if the value of c today is an indication of how much energy was involved in the Big Bang. I'd be very interested in seeing what the esteemed members of this forum would speculate on such universes where c is greater or less than our value today. Is c so finely tuned as other constants such as the fine structure constant?