The use of artificial intelligence by the general population in developed countries such as the US to a "significant" degree will start to take place in the next 18 to 24 months, according to Microsoft co-founder and philanthropist Bill Gates in his year-end letter released last week. The impact on things such as productivity and innovation could be unprecedented, says Gates. "Artificial intelligence is about to accelerate the rate of new discoveries at a pace we've never seen before," wrote Gates on his blog.