I believe the falling tree analogy refers to the fact that when away from an area you do not know what is going on. Should I be in a wood and hear a tree fall, when I leave, perhaps the wood will disappear and reappear should I return (as a scrolling does on a computer game.) However the question can be answered with technology: I can take a picture of the wood (and tree) and when I leave I know it still exists because I can see it. Please Register or Log in to view the hidden image! Thus the gtree makes a noise when no-one is around to hear it.