Three children jump, attempting to touch the first beam of light. Directly across from them, a young man limbos beneath the structure and out into Federation Square. They are some of the first to see UK architect Asif Khan's new work 'Radiant Lines' on display in Melbourne as part of The Light in Winter festival. Forty rings of aluminium - 15m wide and 4m high, lit from within by LED lights - appear to be suspended in space.
'People are naturally drawn to light,' says Khan, observing the interactions. 'It's intuitive. What I want people to feel is a sense of familiarity even though they haven't seen it before. There's a sense that it's pseudo-natural, which I think is why people are drawn to it. It uses crazy technology - there's a lot of stuff happening - but it doesn't show it and the result is more humanistic and almost biological.'
At the centre of the sculpture is a box containing a rotating infrared light. It oversees the whole square and detects motion. As people cross invisible radiant lines, the lighting effect in the circles changes. In a way it's interactive, but the participants aren't aware of their role. It's an extension, although far more abstract, of his MegaFaces Pavilion at the Sochi Winter Olympic Game, where visitors' selfies were transformed into giant 3D portraits.
The linear nature of Federation Square itself was part of Khan's inspiration - 'it's a crossing point of traffic flow, people, trams, trains running underneath, the Yarra River' - as well the natural world. 'What we're seeing is layers of movement,' he says. 'It's basically a three-dimensional world of light, which you would see in nature if you looked at bioluminescent plankton or fireflies or sparks coming off a fire.'
For all the planning involved in the creation of such a technical piece, Khan admits the result is always better than he could ever envisage. 'It's a great privilege to put work into a really public space,' he says. 'Architecture needs people, but that's also the bit of it you can't imagine - people's curiosity.'