Axioms

> Maths is just a language, true. But if we try to define a - six-dimensional universe, say - the maths just doesn't add up. So yes the maths does restrict our universes - it says six dimensions just won't work.
Who told you that? A six-dimensional classic (Newtonian) universe works just fine. Sure, you won't have stable orbits but apart from that it's OK.

You can also construct a quantum field theory for such a universe, it also would work just fine.

I think you're confusing the physics of our universe versus those of any possible universe. Sure, *ours* might not make sense with 5-9 dimensions, but that makes no conclusion about *any possible universe* having such a number of dimensions. Maybe you're just being imprecise with your language in places?

I think you are very confused about the dimensions thing in physics.

Physics tries to model measurements.

So for example you measure a planet that is orbiting, make an equation, and see if tomorrow the equation and the position are the same (within a certain range of precision).

Before Galileo saw that Jupiter had satellites, they had perfectly fine equations that predicted where everything would be in the sky. The problem arose because new data could not fit the model.

You can absolutely model an orbit of a planet using 3 dimensions, or you can model it in an higher space with an equation of a lower degree. Both work. We can't really know which is "exact" if both work.

You can keep adding dimensions and make equations that work, but we don't really know what the "truth" is.