The human brain evolved to cope with the challenges of the African savanna and the primordial forests of Eurasia. Everything we encounter in our quotidian lives exists in three dimensions. Hence our brain isn’t equipped to handle multi-dimensional concepts and it’s most definitely not equipped to handle concepts like boundless-but-finite or boundless infinite.

That’s why we use mathematics. Math lets us handle things our brains can’t really cope with. Even gifted mathematicians can’t visualize an 11-dimensional manifold but it’s relatively easy to model one using appropriate math. We know that there are such things as negative numbers, irrational numbers, and imaginary numbers — but the human brain can’t visualize any of these things. Despite that, we use these every day, often for practical purposes; for example air traffic control systems make extensive use of imaginary numbers in their software programs.

It is thus a huge error to imagine that something cannot be so merely because our tiny limited human brain lacks the cognitive ability to render certain concepts in ways that seem intuitive to us. We evolved enough brain to learn how to crack the shells of nuts and the skulls of our enemies; the fact that a tiny percentage of clever people can do more is astonishing. We should not be surprised that most of us struggle with abstract concepts, especially when we’ve not studied the equations that would give us some purchase on them.

If you want to learn more I highly recommend Leonard Susskind’s lectures on Youtube, especially the Stanford Continuing Education series which is a great basic primer on both relativity and quantum mechanics, both of which have important things to say about cosmology. After that there are Susskind lectures on eternal expansion and bubble nucleation, the Higgs boson, and other topical subjects. The math isn’t difficult and he also uses Feynman diagrams and Penrose diagrams to render concepts visually for those who prefer that approach.