light

Different types of bulbs emit light in a different way. And so there was a particular kind of filament that created a strange artifact at the top of the bulb. It literally was an optical illusion.

Val Ravaglia, Val Ravaglia on Displaying Digital Art at Tate

Because copy machines use heat, light, pressure, what are natural forces in the world, to engage students in a different way of thinking about making artwork creatively, she created two classes called Process One and Process Two.

Joan Truckenbrod, The 1970s Artist-Programmer: Truckenbrod, Dehlinger