One time, John Mainstone -- a Queensland professor who curates the Pitch Drop experiment and has made it his mission to observe its fall -- stepped out to get tea. During the 15 minutes he was away, because of course, the pitch dropped. Another time, later on, Mainstone and his colleagues put video-monitoring technology to use to record the moment even if no humans were nearby to see it. The equipment malfunctioned. The pitch dropped, unobserved.