STOCKHOLM—The annual announcement of Nobel Prize winners was once again marred by vandalism this year, with triumphant fans of the 2011 laureates mobbing Stockholm streets last week, breaking shop windows and setting bonfires as they celebrated remarkable achievements in economics, physics, medicine, and other disciplines. “Fuck yeah, rapidly solidified alloys shown by means of electron diffraction to possess icosahedral symmetry—a little phenomenon known as quasicrystallinity, bitches!” said one chemistry fan who helped overturn a parked car as a mob chanted the name of prizewinner Daniel Shechtman. “Number one, motherfuckers!” Nobel officials said this year’s rioting is Stockholm’s worst since 1971, when Chilean poet Pablo Neruda’s prize for literature sparked three days of bloody unrest that left 19 dead.