Pi in the Sky (close up)

Pi has been calculated to trillions of digits and memorised to thousands but how many do we actually need? To calculate the circumference of the observable universe to within the width of a single atom – just the first thirty-nine. Here they are, circled in the colours of the cosmic spectrum. Materials: silk thread, brass rings, painted wooden battens Techniques: Bands: hand-woven on an Inkle loom; Brass rings: hand-wrapped