Sitabhra Sinha and Raj Kumar Pan of the Institute of Mathematical Sciences in Chennai analyzed data on about 2000 films released in the US between 1999 and 2004. They found that the total income distribution of all movies released in a particular year followed a power law with a tail that had a "Pareto" exponent of 2. The distribution of wealth in many western countries follows a similar pattern. Sinha and Pan also observed that the income per cinema of all movies -- regardless of their success -- follows the same power-law decay curve over about 20 weeks.

"These results mean that, for the high-earner movies, the opening pretty much determines how it will perform over its entire theatre lifetime," Sinha told PhysicsWeb. "As such it lends support to the classic "blockbuster" strategy of opening the movie simultaneously on as many screens as possible -- a strategy that has been used since Jaws."

However, the results are puzzling because the Pareto tail in wealth distributions are often explained in terms of interactions between "agents", and movies do not interact with each other directly. Moreover, the power law also applies to the income in the opening week of the film, before film-goers themselves have had time to interact with each other.

"Even more important, the exponent of two associated with the tail is quantitatively identical to that seen recently for other popularity distributions, such as the number of citations of scientific papers and online sales of books," says Sinha. "These results may be offering a glimpse of a universal dynamic that underlies the emergence of popularity -- of a product or idea -- in society."