Glastonbury has hosted some of the loudest rock bands in the world and is known for its rowdy crowds and high jinks. What could be bolder than asking for silence at an event of this scale? Marina Abramović, the acclaimed performance artist who has dedicated her life to pushing the boundaries of conceptual art, is about to stage her largest-ever participatory work at Worthy Farm this evening. At 17:55 GMT, just before PJ Harvey’s set, the 77-year-old Serbian artist will take to the Pyramid Stage for seven minutes of silence. Hardly out of step for an artist who has done naked stand-ins, laid in…