Bill, you've forgotten your quantum theory.The act of stumbling across it collapses the probability wave from an indefinite 'sod all' activity to a definite mission based on the overall strategy and defined by the referee in whatever detail is necessary.
Icosahedron,
That's a very good analogy actually and for a great many things other than the IN too.
Nothing really exists from the players' frame of reference until they observe or otherwise interact with it. However, as you also point out...
But you do still need a vague overall IN strategy.
While something may not yet exist as far as the players are concerned, the GM must be ready for the moment when the players collapse the wavefront. There are somethings you cannot make up in the fly.
Regards,
Bill