I like to think the art is connected with values (like beauty, ugly, nice, boombastic or just boring, sad, exciting etc). I mean if any picture (in physics it's only the wave of photons) or sound (it's just moving air) moves us, our emotions, our intellect than we can say it's some kind of art. In this way of thinking the art is not the object, but connection between receiver and transmiter. Nighly philosophy ;)