An extremely deep dive into the three-second chord that opens A Hard Day's Night. You can hear it in your mind; here is the best guess yet as to how it was constructed. “For the honour of all mathematicians, I would like to put the record straight — or at least straighter. The tale of the Beatles’ Magical Mystery Chord is a tale of 18th century mathematicians, the study of heat, Karaoke tricks and a measure of luck