The self-proclaimed world's longest piece of music has being going on for 5 years and is supposed to last a total of 639 years.

As music I have to give this a great big *yawn*, as performance art ... okay, it gets a polite golf clap. Don't get me wrong it *is* interesting to explore the boundaries of what we call music, in this case by the gross temporal exaggeration of this 20 minute piece John Cage piece written in 1985.

In addition to making folks (re)consider now that's what I call music *ahem*, it is also interesting to note that the human sense of time and attention span live in a very fixed range, with experimental music composers clocking in on the high end and hungry 2 year olds on the low end. This related to something in our heads called the specious present. From Wiki:

The specious present is the time duration wherein one's perceptions are considered to be in the present. This term was first used by psychologist E. R. Clay and the concept was further developed by Harvard professor of philosophy William James.

Music, by my definition, regardless of the nature of the sounds or unsounds, has to sync up with our perceptual apparatus or at least be within a comparable order of magnitude. This is because the interpretation of those sounds by the mind is where music the emerges. A work that no mind will ever hear in its entirety or even a quarter of its entirety, for me, is hardly musical at all.