The infinite vastness of space.

One way of visualizing space as infinite is to imagine that it's curved in such a way that if you keep traveling along a trajectory, you'll end up in the same location after a certain distance. Kinda like being able to walk around the earth infinite times. A never ending journey.

That could work by wrapping our three dimensional space around a fourth dimension, no?

< Doesn't know pomegranate about physics.