There are a few different ways to look at it. This is my favorite: 1000 years ago, if you had an original idea (the invention of the in-home toilet for example), it might take a couple years for you to make it a reality. Digging, designing, tying in to rainwater sewer, installing, etc. 110 years ago, you invent the personal automobile. It takes 2 years to get a model in production that actually works. 10 years ago, you invent Facebook or the iPhone and it takes 1 year to launch. 5 years ago you invent Twitter and it takes 6 months to launch. Thinking of an idea and making that idea a reality takes less and less time the more we progress. So- if that trend continues, the theory is we'll reach a point of instantaneous thought and creation. You invent it in your head and it manifests in the real world real-time. The singularity.