The Turing Test has been the classic test of artificial intelligence for a while now. The concept is deceptively simple - to trick a human into thinking it is another human on the other end of a conversation line, not a computer - but from what I've read, it has turned out to be very difficult in practice.
How close have we gotten to tricking a human in the Turing Test? With things like chat bots, Siri, and incredibly powerful computers, I'm thinking we're getting pretty close. If we're pretty far, why are we so far? What is the main problem?