screen a mirror, instead of the screen a thorax, instead of electric light fire, instead of light reactions chemical reactions, one can work with or without celluloid, in the cinema or outside it, with or without screen, with moving or static screen, with the camera as projector, with the people as screen, etc.»[43]

The technological further development of computer technology makes it possible today to re-execute the concepts of the 1960s and 70s in spatial and active integration of the beholder in the artwork with technological means. Jeffrey Shaw, for example, one of the initiators of inter-media events like «Movie Movie,» resumes the participative approaches in computer supported virtual (projection) environments.

Light and movement

An extended concept of media art also encompasses the use of light and movement as artistic material. Already in the 1950s, artists of the group ZERO like Heinz Mack, Otto Piene and Günther Uecker worked with light as an artistic medium. Their intention was to return painting to its conditions, that is, in particular

light as a foundational element. In so doing, however, they abandoned the technique of painting with paint and canvas and formed spatial works that threw shadows or reflections and included movement in their concept. Works emerged that created an impression that changed according to the point of observation. Instead of color or other formal components, Heinz Mack considered spatial organization and movement as the true form of artistic work.[44]

Particularly the inclusion of the variable perspective of the viewer is an important component of many space-referential art works. While the visitor walks through a space, there is no fixed point that provides an optimal perspective of perception. Movement and orientation in space are thereby an intended element of the visitor's experience.

Since the 1970s, James Turrell[45] has been creating installations that make the immaterial, that is, light, physically available to experience. These light spaces cause intensive visual events and often pose perspectivist riddles to the visitor. In his spatial installations, which can be entered by the viewer, he