Dear friends and colleagues, I have the please to announce the colloquium talk on Friday, 6 January 2017 at the University of Wollongong in room 6-210 given by Professor Sir John Ball (University of Oxford) on "THE MATHEMATICS OF LIQUID CRYSTALS" Abstract Liquid crystals are nonlinear fluids whose constituent molecules have orientational, and possibly some positional, order. They are used in a wide range of applications including computer screens, televisions, instrument panels and signage. The lecture will review the main mathematical theories of liquid crystals, and some challenges involved in the description of liquid crystal defects.