Roses aren't red and violets aren't blue. At least that's the premise of a new book, 'Outside Color', which puts forward the debate that colour is, in fact, an illusion. Author Dr Mazviita Chirimuuta uses the book to explore the historical debates that suggest colour doesn't exist - at least not in the literal sense. Light, however, does exist, and it's the mind that transforms that light into colour. 'Of all the properties that objects appear to have,'writes the University of Pittsburgh professor, 'colour hovers uneasily between the subjective world of sensation and the objective world of fact.' Optical illusions,...