I don’t understand this well myself, but my understanding is that the 3D universe wraps into a ball in the 4th dimension. Just like on a balloon the 2d space on its surface wraps in the 3rd dimension. To creatures who can only perceive a 2d world it seems odd that their world has no limit, but from a 2d perspective you can’t reach some limit on the surface of the balloon. Just as you cannot travel in one direction on the earth’s surface and ever reach a limit.

The size of our universe would then the be circumference of this ball. But that doesn’t mean there is a world outside this ball.

Geek dad, living in Oslo, Norway with passion for UX, Julia programming, science, teaching, reading and writing.

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store