The World Only Exists As Long As You’re Looking At It

Whenever you turn a corner or close your eyes, the world around you ceases to exist. The only part of the world that exists is that which is currently in eyeshot. Whenever you move, the world you no longer see ceases to exist and the world you now see pops into existence.

People, too, only exist whenever you can see or hear them. When someone walks past you, they really have just popped into existence, walked in front of you, and then disappeared as soon as you look away from them again.