When battling Labor Day traffic, an irritated motorist might respond with the sort of language that comic strips represent by a string of symbols.
For Benjamin Seibold, traffic evokes different kinds of symbols: Greek letters and differential equations.
An assistant professor of mathematics at Temple University, Seibold studies "phantom" traffic jams - those aggravating road delays that occur for no apparent cause other than high volume.
Cars get packed too tightly together. Someone hits the brakes, prompting drivers behind to respond in kind. And a wave of braking ripples backward along the roadway.
Seibold and his colleagues gained notice last year when they reported that, mathematically speaking, these waves of slowing traffic behave like shock waves from an explosion.