I imagine all of collective known knowledge as a sphere Which is finite which is depicted by boundaries or surface of the sphere And the sphere is growing . Uneven growth in all directions 4pi steridian.
Why a sphere and not just a circle or conversely a hyper-sphere in many dimensions? The idea of sphere and growth with 4pi steradian suggests you imply something on the fundamental number of dimensions of knowledge (that may or may not exists).
Regarding the growth of this "sphere": if you consider that a human brain is finite and can hold only a finite quantity of information, then there must be a point where any new concept is too large to fit. Hence, the growth stops somewhere, unless we find a way to go beyond this natural limit (but then, are we still speaking of human beings?).