In other versions, including later tweaking by Moore himself, the general theme is that computing power will double roughly every two years, based on the idea of being able to fit twice as many transistors on a same-sized circuit. Intel has tweaked that further to an 18-month period based on the transistors getting further.The article further points out:
Now Kaku says that as things stand, Moore’s law will “flatten out completely” over the next 10 years. That’s based on the idea that we are beginning to hit the physical limits of silicon. Specifically, if transistors get any smaller, the inherent problems of overheating and leakage will eventually outweigh any gains.
Back in 1999, I had a professor who stated that there was no way we'd get computers faster than one gigahertz because of the space between the atoms of silicon. Today, we have smart phones that operate at higher than one gigahertz to say nothing about full computers - and they are still getting faster! To be fair, engineers figured out how to push silicon atoms further apart to increase better microchips. Dr Kaku goes on to explain alternatives to overcome the limitations of silicon.
Moore’s Law Could Be No More