Some physicists actually believe that the universe we live in might be a hologram.
The idea isn’t that the universe is some sort of fake simulation out of The Matrix, but rather that even though we appear to live in a three-dimensional universe, it might only have two dimensions. It’s called the holographic principle.
The thinking goes like this: Some distant two-dimensional surface contains all the data needed to fully describe our world — and much like in a hologram, this data is projected to appear in three dimensions. Like the characters on a TV screen, we live on a flat surface that happens to look like it has depth.
It might sound absurd. But if when physicists assume it’s true in their calculations, all sorts of big physics problems — such as the nature of black holes and the reconciling of gravity and quantum mechanics — become much simpler to solve. In short, the laws of physics seem to make more sense when written in two dimensions than in three.
“It’s not considered some wild speculation among most theoretical physicists,” says Leonard Susskind, the Stanford physicist who first formally defined the idea decades ago. “It’s become a working, everyday tool to solve problems in physics.” Source