While he was the director of research and development at Fairchild Semiconductor, Gordon E. Moore predicted that the number of components in an integrated circuits would double every year. Later, this time-step would slow to every two years; you can occasionally hear people talk about eighteen months too, but I am not sure who derived that number. In a few years, he would go on to found Intel with Robert Noyce, where they spend tens of billions of dollars annually to keep up with the prophecy.
It works out for the most part, but we have been running into physical issues over the last few years though. One major issue is that, with our process technology dipping into the single- and low double-digit nanometers, we are running out of physical atoms to manipulate. The distance between silicon atoms in a solid at room temperature is about 0.5nm; a 14nm product has features containing about 28 atoms, give or take a few in rounding error.
It has been a good fifty years since the start of Moore's Law. Humanity has been developing plans for how to cope with the eventual end of silicon lithography process shrinks. We will probably transition to smaller atoms and molecules and later consider alternative technologies like photonic crystals, which routes light in the hundreds of terahertz through a series of waveguides that make up an integrated circuit. Another interesting thought: will these technologies fall in line with Moore's Law in some way?