I think you have it backwards. It's nothing like a mathematical theorem, since you can't really prove anything about the subjective human experience of listeni

I think you have it backwards. It's nothing like a mathematical theorem, since you can't really prove anything about the subjective human experience of listening to music. Physics on the other hand, though it relies on mathematical models, can't really explain why the universe exists in the particular way that it does. The best we can do is use the scientific method to make very educated guesses at an accurate mathematical model that might help us accurately explain the behavior of some physical system we're interested in. Physics is full of inconsistencies and unexplained phenomena, but we're slowly getting better at making predictions. Music theory is the same way. Music sounds good to humans, and there doesn't really need to be a deeper reason than that for me to listen to a song over and over. Music theorists will study the music that people tend to like / dislike, and do their best to come up with an explanation for why -- often by pulling it apart into its core components, comparing it to other works, analyzing chord structure, voicing, instrumentation, etc.. In the end, just as with physics, composers have slowly built up a reliable foundation of knowledge to help them compose music that will reliably sound "good". But every so often someone comes along with an earworm that can't fully be explained.