I found this article from the good folks at the Machine Intelligence Research Institute to be a good read. To save you the trouble, the bottom line is, nobody knows. Some folks say maybe by 2040. Others, sooner (Kurzweil), like around say maybe 2030. Others, later … maybe a lot later … as in, maybe never.
One of my favorite statements on the subject by one of my favorite modern thinkers (David Gelernter) was made during a debate between himself and Kurzweil on the subject at an MIT symposium held around 2007 or so. I’m paraphrasing here, but in response to Kurzweil’s assertion that a digitally-modeled human brain would necessarily give rise to true AI, Gelernter said, “No matter how well we model a rain storm, nobody gets wet.”
Whether or when general-purpose, human-competitive machines (with true AI) are ever created remains a matter of prognostication as much as science. But one thing is certain — the journey to AI is a mirror to a better understanding of ourselves.
My hunch is that AI won’t be “created” — but it might “evolve.” More on that later.