In the familiar world, there are three dimensions. But physicists allow for the existence of hidden, curled-up directions. If one of them is twisted into a Klein bottle, a surface with no inside or outside, fundamental laws break down. This shape violates CP symmetry, a rule of the Standard Model that dictates matter and antimatter should be created in equal amounts.
In the curved dimension, a dense layer of virtual pairs arises — something like a fog of unborn matter. Our three-dimensional universe, like a ship, glides through this fog. From the friction with it, real particles are born, but due to the symmetry breaking — slightly more matter. Just one extra proton per billion is enough to give rise to galaxies and us.
This mechanism elegantly explains the mystery of the early universe: where the matter came from. Without this microscopic imbalance, the world would have remained empty.
A Klein bottle cannot be constructed in a three-dimensional world: it intersects itself. Its true form is revealed only in four dimensions.