If the thing you have to sort is within a known ___domain you can definitely beat o(n log(n)). Just expect crazy memory usage.
And that's only not the case in theory. But nobody owns a real Turing machine with infinite tape and truly infinite numbers. It doesn't exist in reality.
You can always divide time by multiplying space with the same factor.
by "general sort" your parent comment means "comparison sort", and the claim (which has been proved, see CLRS intro to algorithms) is that you cannot do it in better than O(n log n) comparisons.
And that's only not the case in theory. But nobody owns a real Turing machine with infinite tape and truly infinite numbers. It doesn't exist in reality.
You can always divide time by multiplying space with the same factor.