Norvig's Law (2002)

We all know about Moore's and Gilder's laws, that CPU power and bandwidth will double every 18 and 6 months, respectively. Less familiar are the more pessimistic laws, such as Proebsting's law, which states that compiler research has led to a doubling in computing power every 18 years. In July 1999, there was a news article stating that PC usage had doubled yet again, reaching penetration of 50% of homes. Any technology that surpasses 50% penetrationwill never double again(in any number of months). If you're counting units sold, you can double your count by selling everyone 1 unit, then 2, then 4, etc. If you're counting the total number of households that own the product, you can double your count by doubling the population, or by convincing everyone to divorce and become two households. If you're counting percentage of people, there's just no more doubling after you pass 50%. So the next time you hear about the doubling of another technology, remember you heard it here first.