How long is a piece of classical music? Really.

This post is a continuation of my previous "How long is a piece of classical music?".

In that post, I examined the implications of Peter Breiner's "InstaConcerto." Breiner wrote this piece for the purpose of brevity. He composed social media posts as much as he wrote music.

Here, we will see a piece written to be unimaginably long. If successful, one performance that is going on right now could be finished by the great-great-great-great-great-great-great-great-great-great-great-great-great-(yes, that's 13 greats) grandchildren of the people that started it. Fortunately, this performance with its 639 year length is the only one of its kind.

The piece in question here is John Cage's "As slow as possible." Originally written for organ in 1987, it gets performances that last 8, 12, 24, and even 48 hours. The piano version runs between 20 and 70 minutes. An organ can sustain a longer performance, because it can hold notes indefinitely, while the sound from a piano dies away.

This super long performance takes place in the Halberstadt Cathedral in Germany. No one actually plays the piece, rather the performers move weights to different pedals when notes need to change. They don't need to worry about moving anything until September, 2020, which is the next scheduled note change. The organ being used for this performance was specially built for this piece, and the performers actually installed the pipes as they became needed for notes.

Any parameter of music can and will be exploited by composers. Since music, by its nature, manipulates time, time becomes a "go-to" way of creating interest.

Most music reflects the aesthetics and attitudes of its own time. What happens when a piece's time spans centuries? Could this piece go out of style before the performance of it is over?