In Eric Frank Russell's Now Inhale and Arthur C. Clarke's Nine Billion Names of God there are described Buddhist monks who have a task which will seem to take aeons to complete in order to bring about the end of the universe. I've seen this pop up a few times in pulp-era SF. My question is- are there any actual groups of people (they don't necessarily have to be Buddhist) who are busy working on a similarly seemingly impossibly long task which, upon completion, will end the universe?
The long version of 4'3" by John Cage doesn't count because they don't believe the world will end once they complete it.