Roberta Smith’s obituary of John McCracken delves into the artist’s interest in other-worldly ideas:

“Even before I did concerted studies of U.F.O.s,” he oncetold an interviewer, “it helped me maintain my focus to think I was trying to do the kind of work that could have been brought here by a U.F.O.”

It was no wonder that some people thought Mr. McCracken had designed the monolith featured in Stanley Kubrick’s 1968 movie “2001: A Space Odyssey.” He did not do it, although he sometimes said that his work might have influenced whoever did.

Mr. McCracken’s signature work was a lustrous, intensely colored monochrome plank that leaned simply and provocatively against the wall. It was inspired in part by the West Coast’s car culture — he once described cars as “mobile color chips.”

In interviews he usually cited his greatest influences as the color fields of the Abstract Expressionist Barnett Newman and Minimalists like Donald Judd, Dan Flavin and Carl Andre. Mr. McCracken hit on the plank idea in 1966, in a period when artists across the stylistic spectrum and on both coasts were combining aspects of painting and sculpture in their work and many were experimenting with sleek, impersonal surfaces.

Roughly the size of a plank of lumber, the leaning pieces were so casual as to seem like jokes, except that their intense hues and flawless surfaces projected dignity and beauty; they often seemed to be made of solid color, but also had a totemic presence. Mr. McCracken saw the leaning pieces as existing “between worlds,” not only linking floor (the realm of sculpture) and wall (painting), but also matter and spirit, and body and mind.

John McCracken, Sculptor of Geometric Forms, Dies at 76 (New York Times)