The Halting Problem

"You have done it, Fred! You have found the Operating System for the Universe!"

"Seems like it, Bill. I think I have finally gotten a hang of the mentalism interface! Watch this:"

A perfect pure diamond sphere, exactly 1.0cm in diameter, materialises on the instrument-laden workbench, exactly 30.0cm in front of Fred.

As the euphoria fades, Fred suddenly feels tired; it’s been a long, momentous day, after all. He turns to Bill and says: "Why don’t we take a break now? Today has been hard work! We can come back, refreshed, in the morning. Halt now."

And the Universe—quietly and efficiently obeying the still-active mentalism interface—did just that...