An interesting article on io9 unveils a curious law that can apparently predict the size of cities - a law developed by a linguist. The original version of Zipf's law states that in any language, the most common word was used twice as much as the second most common, three times as much as the third and so on. It seems though, that this law also applies to the populations of the cities in a given country. And the most interesting part? Nobody really knows why. You can read the full article here.