No, not the friendly hand wave, but the sporting event stadium wave. Mathematicians from the University of Exeter have solved the mystery of unaccountable traffic jams. You know, those traffic jams that involve no wrecked cars or other traffic-disrupting accidents, but are still capable of bringing traffic to a stand-still.
The big brains at the University of Exeter developed a model that shows how the most minor and minimal event can create a "backwards traveling wave." Think of it like how a wave starts at a stadium. A single drunk hooligan wants to start the wave. He gets his friends into it, they get the row into it, and the row gets the section to do it. Eventually on the other side of the stadium every person is raising their hands like a moron.
The same concept applies for traffic. When a jackass in a Miata (at least here in Dallas that is the most common occurrence) quickly enters the freeway and tries to merge four lanes over in steady flowing traffic, the small braking reaction from the non-jackass drivers behind the Miata builds up until five miles down the road traffic comes to a complete stop.
So when you are sitting in traffic trying to make it home for the holidays, don't be angry and bitter at the cars immediately around you. It's not their fault. However, feel free to curse out the schmucks five miles up who've slowed down for some silly reason and thus disrupted the flow of traffic. [Science Daily]