Organ²/ASLSP (As SLow aS Possible) is a music piece by John Cage and the subject of one of the longest-lasting musical performances yet undertaken. It was originally written in 1987 for organ and is adapted from the earlier work ASLSP 1985; a typical performance of the piano version lasts 20 to 70 minutes. In 1985, Cage opted to omit the detail of exactly how slowly the piece should be played.
The performance of the organ version at St. Burchardi church in Halberstadt, Germany, began in 2001 and is scheduled to have a duration of 639 years, ending in 2640.
On February 5, 2009, Diane Luchese performed “Organ²/ASLSP” from 8:45 AM to 11:41 PM in the Harold J. Kaplan Concert Hall at Towson University. This 14 hour-and-56-minute performance, in strict adherence to the score’s temporal proportions, is the longest documented performance of the piece by a single person so far, although a full 24-hour performance of the original piece, ASLSP, was given by Joe Drew during the ARTSaha! festival in 2008. Drew has also given 9- and 12-hour performances of the piece, and is planning a 48-hour performance.
On September 5, 2012, as part of John Cage Day at the University of Adelaide, Australia, Stephen Whittington performed an 8-hour version of ASLSP on the Elder Hall organ. The eight sections of the work were each allocated an hour, with each section divided into segments of one minute, within which the precise timing of events was left open. In performance, seven sections were played, with one omitted and one repeated. Organ registrations were determined by chance procedures.