Imagine this…

“A powerfully magical, but very dickish witch decides to cast a spell on all of humanity. With a single swoop of her wand, she makes all man-made objects vanish and restores the Earth to its pre-human, 200,000 BC state. What’s left is 7.3 billion naked humans, standing on grassy plains, in forests, in swamps, on tundra, and in deserts in the exact spots where their cities and villages were just a second ago. The humans themselves are unchanged—each person knows everything they know right now.

The only other thing is that in each of their hands is a piece of paper with a note in their language that says, ‘I’ve cast a spell on all of humanity because why not. Here’s how it works: everything will remain as is until humanity manages to create a fully-featured and perfectly functional iPhone 6S. As soon as that happens, the spell will be reversed and all man-made objects will instantly reappear.’

One minute later, the notes all vanish.”