Artistic licence: The genre genie is born

‘‘Math rock? What’s math rock again?” I said. ‘‘Doesn’t it have something to do with time signatures?” my music journalist friend replied, a vague hope flaring in his eyes. ‘‘I think bands like Battles and Explosions in the Sky play it,” I added.

That was when it hit us. Despite being paid to pen articles about music for a living, we were struggling with the myriad new categories into which rock now seems ...