I read this thread just now and I was going to respond to it (how the term ‘learning curve’ is quite appropriate, but taxslave stole my thunder.
I would like to add one point to his post as to how the term learning curve is quite appropriate. In mathematics, there a concept called ‘asymptote’. Asymptote is the Y value which a curve will attain at the X value of infinity.
So as X become larger Y will also become larger and will approach the asymptotic value, without ever attaining it (not all the curves show this property, some do).
Learning is similar to that concept. As you learn about a subject (learn Physics, or learn to play chess), you gain more and more knowledge, you become more and more of an expert in it, without ever achieving perfection. You approach perfection asymptotically.