The world will never run out of oil.

This is a thought experiment I heard from Coworker Lee.

Imagine the following scenario. Take an Olympic-size swimming pool, drain the water and fill it with peanuts -- the kind still in the shell, like the overpriced ones you can buy at the ballpark. Invite the hungry and the needy to the pool to take with them a free meal of peanuts. But there's a catch: they must immediately shell the peanuts and return the empty shells to the pool.

On the first day the pool would be a peanut bonanza. To start all shells would contain edible parts within, and one could gather a meal's worth by stooping over the pool's lip and scooping a handful. Done. And for a while -- just how long depends on how many people are doing the peanut mining -- it would remain easy because the unshelled peanuts would be concentrated in spots. But over time you'd have to work harder by wading through empties to get to the non-empties farther away in the middle of the pool or buried a few feet beneath a surface of mostly picked over shells. But despite the increase in effort, you could still get a free meal of peanuts quickly.

The real difficulties would begin once all areas and depths of the pool have been picked over and the unopened shells remain scattered throughout. And as peanuts continue to be shelled and eaten and the pool filled with ever more empties, the job of gathering a full meal's worth of peanuts would require increasingly more effort and time. Indeed, the last peanut would never be found and never be eaten. Imagine searching for the last remaining peanut in an Olympic-size swimming pool -- even without a deep end!

The last peanut would never be found. And so wouldn't the second-to-last. Or the third-to-last. The question is: how many peanuts would remain uneaten simply because it was easier and faster to procure a meal somewhere else? When does the free lunch become too expensive?

The world will never run out of oil.