There is a fundamental law of physics, that momentum is conserved. It's not the only thing…

I like to think that such a law exists for the Conservation of Intonation. Every time some poor tenor in New York City is singing sharp, there's a bloke in London who's inexplicably singing flat to restore balance, to keep the universe “in-tune”.

This may go further. Humans on the whole are lazy vocalists and instrumentalists, spending most of their time under-pitch. Presumably, this means that in some other part of the universe, there's a whole alien race that is suffering from all their musical performances sliding sharp. Poor aliens, that must be tiring.