In the darkened space of the main exhibition hall, a luminescent rainbow arches across the opposite wall, extending from one corner to the other. Geometrically speaking, a rainbow is actually a circle that only appears to be an arch because of the horizon line. If the floor of the gallery here did not block our view, the rainbow would appear as a full ring. Whereas rainbows in nature result from sunlight hitting water droplets at exactly the right angle, Open is produced by shining a bright white light on a prism, which bends the light to make the familiar colours of the spectrum – red, orange, yellow, green, and blue. The mechanism used to create it is partly visible in the space, like instruments in a science experiment.

The work continues Olafur Eliasson’s investigation of colour phenomena, a central concern for much of his work across all media, from large-scale installations to photographs, sculptures, and light projections. The artist is fascinated by the relativity of colour perception, by the fact that how we see colours is extremely individual and dependent upon context. ‘Colour’, he writes, ‘does not exist in itself but only when looked at. The unique fact that colour only materialises when light bounces off a surface onto our retinas shows us that the analysis of colours is, in fact, about the ability to analyse ourselves.’