Olafur Eliasson is a Danish artist who is interested in the extent one may have an impact on their world. An essential aspect of his art is that it directly involves the viewer in a space that is traditionally not accessible to the viewer for participation. Popular mediums of Eliasson’s include light, mirrors, shadow, color, wind and fog. The following piece is titled ‘slow-motion shadow in colour’ 2009 and until 2 days ago, it was on show at the 21st century museum of contemporary art, kanazawa, japan.
“with this exhibition, eliasson re-proposes the idea of the art museum, to be seen not just simply as a facility in which to view art in a context which is removed from society, but more as a public space, with the potential to engage society and the urban environment. a space in which to question our presence within this world.” >> http://www.designboom.com/weblog/cat/10/view/9467/olafur-eliasson-your-chance-encounter.html
Here is a link to a list of Eliasson’s works (coupled with small images of the works) from his website:
http://www.olafureliasson.net/works.html
Process and Practice 
commentary