The idea of negative space has fascinated me since I first heard about it. It changes the way you think about painting when you stop trying to paint 'things' and paint the space instead.
Sometimes negative space is "the space between", which also suggests metaphorical interpretations, and reminds me of my research into how people talking together cross the gap of understanding that lies between them.
Recently, I've been dipping into French existentialist philosophy (prompted by Sarah Bakewell's excellent book At the Existentialist Cafe). There I found a further extension of negative space, into 'specific nothingness'. This idea from Jean Paul Sartre captures that feeling of something or someone actively absent. For example, if you think you have a whole bar of chocolate in the cupboard, but when you get there you find only half a bar, the missing half is what draws your attention. And in a more serious vein, Bakewell writes of friends of Sartre and de Beauvoir who they would meet in the cafe but who then disappeared during the war - their absence in the cafe would be strongly present.
I have been thinking a lot about this idea of "the presence of absence" and applying it to my experience here in Berlin.
Yesterday I showed a new audio-visual piece on the theme at our group workshop. It included some exploratory collages made after watching the film Jezebel (from 1938). There is definitely more to be done with the presence of absence.