A major problem in understanding contemporary (and future) cities is the fact that they ‘appear’ to be changing faster than we can keep up. Our theories which were culled in the last half century about how cities are spatially organised now seem passe. New notions of interaction and the shortening of our attention spans are changing what we consider important in cities. In my current editorial in Environment and Planning B (Volume 41, pages 1-2, 2014), I elaborate this thesis and argue that we may well have to learn to live in a world where our theories are as liquid and as temporary as our behaviours and the processes that determine the structures of what in the past we have taken for granted and considered as being long-lived.