Norvig's Law states "Any technology that surpasses 50% penetration will never double again"
Oftentimes, in rapid growth items like software adoption or stock prices, people excitedly report "it grew by 50%!"
It's a simple mathmetical statement - it can't double past 50% again.
This law does depends what you measure, as sometimes, something can double multiple times past 50% growth (like a stock price).
But for something like software adoption, Norvig's law is absolute!