Here is a question that might be somewhat more philosophical than this community cares for. If so, I apologize in advance. Are there any reputable theories as to why the speed of light is constant? I know that it is an empirical fact and therefore that it does not need to be proven. But on the other hand, the aim of physics has historically been to come up with satisfying theoretical explanations for empirical facts. Anyway, I'm just wondering if there are any reputable ideas out there that modern physicists are considering.