Belgian physicist Francois Englert reacts as he appears next to his wife Mira at the balcony of his house in Brussels October 8, 2013, after he and Britain's Peter Higgs won the 2013 Nobel prize for physics. The two scientists won the prize for predicting the existence of the Higgs boson - the particle key to explaining why elementary matter has mass - the award-giving body said on Oct 8.[Photo.Agencies]