If this whole argument seems circular, that's the point. Prominent people stay popular for longer than they ought to because they serve as conversational fodder, which in turn drives more media coverage.
"Take Paris Hilton, somehow or another she became well known and now people are more likely to talk about her," Fast says.
Mark Schaller, a psychologist at the University of British Columbia in Vancouver, Canada, agrees. "It does provide an answer to the question of why fame is self-perpetuating, even when the famous person isn't doing anything fame-worthy anymore."
What is less clear is how people, ideas and practices become prominent in the first place, Schaller says. In baseball, performance is likely to provide the initial inertia to stardom. But other aspects of culture come into prominence because of a quality that Schaller calls communicability.
"Catching an idea is not a whole lot different in some metaphorical way than catching a disease," he says.