I tried to explain it in my recent post, that on current level of technologies human level AGI is possible, but foom is not yet, in particular, because some problems with size, speed and the way neural nets are learning.

Also human level AGI is not powerful enough to foam. Human science is developing but in includes millions of scientists; foaming AI should be of the same complexity but run 1000 times quicker. We don't have such hardware. http://lesswrong.com/lw/n8z/ai_safety_in_the_age_of_neural_networks_and/

But the field of AI research is foaming with doubling time 1 year now.