Elon Musk and other prominent Silicon Valley kooks may hold the belief that we live in a simulation, but one conspiracy theorist speaking at the Flat Earth Convention in England last weekend articulated an even stranger theory about our home, the Earth: the'Pac-Man effect.' Flat Earth belief is what it sounds like, but there is some nuance: though Flat Earthers avowedly don't trust scientists and generally think NASA is a giant conspiracy, their central tool for refuting the Earth's roundness is basically aligned with the scientific method. After all, from the perspective of any one individual, the Earth does appear to be flat. Some observable phenomena line up with this basic perception, but others--like east-west plane flight, which shouldn't be possible if the Earth was a disk, or a diamond, or any other flat shape considered by Flat Earthers--do not. This conflict has led many in the Flat Earth community to come up with conceptual write-arounds to explain the presence of these phenomena that don't fit in their world-view. Here are a few of their theories--and why they don't line up with what we know.