@rahl: Then wouldn't whatever it is that's beyond it be infinite? But anyway, I think this is really digressing from the point.
Is infinity a number (loosely), a unit, or something else?
I argue that it's a number, that is, it's numeric and requires a unit. In which case it follows that you can have:
- ∞ meters
- ∞ seconds
- ∞ minutes
- ∞ revolutions
If you posit that the universe is limited, and nothing that is measurable can extend past the universe, that means that you cannot have an X that is ∞ meters.
In order to prove that infinity does not exist, you must prove that there cannot be ∞ seconds for something... ie that it can't be the case that the existence of A has a starting point (in time) and no ending point, ever. You must also prove that something cannot revolve, rotate, or otherwise move cyclically for an infinite number of times. (a corrolary of the second point)
I'm tired, so I'm sure there are some categories of measurement that i've left out; feel free to append to this list.