From website http://www.lipsettdiaries.net/?page_id=8
"Arthur Lipsett (13 May 1936 – May 1, 1986) was a Canadian avant-garde director of short experimental films."
"Lipsett's film 21-87 was a profound influence on director George Lucas who included elements from 21-87 in THX 1138, his Star Wars films and also American Graffiti. The film 21-87 has been credited by Lucas as the source of the "The Force" in Star Wars.
. Lucas never met the filmmaker but tributes to 21-87 appear throughout Star Wars. For example, the holding cell of Princess Leia in Star Wars Episode IV: A New Hope on the Death Star is cell No. 2187."
Reference about the force at 3:32
Life After Darth
"Lucas never met the young Canadian who influenced him so deeply; Lipsett committed suicide in 1986 after battling poverty and mental illness for years. But like a programmer sneaking Tolkien lines into his code, Lucas has planted stealth references to 21-87 throughout his films. The events in the student-film version of THX took place in the year 2187, and the numerical title itself was an homage. In the feature-length version, Duvall's character makes his run from a subterranean city when he learns that the love of his life was murdered by the authorities on the date "21/87." And in the first Star Wars, when Luke and Han Solo blast into the detention center to rescue Princess Leia, they discover that the stormtroopers are holding her as a prisoner in cell 2187.
The rabbit hole goes even deeper: One of the audio sources Lipsett sampled for 21-87 was a conversation between artificial intelligence pioneer Warren S. McCulloch and Roman Kroitor, a cinematographer who went on to develop Imax. In the face of McCulloch's arguments that living beings are nothing but highly complex machines, Kroitor insists that there is something more: "Many people feel that in the contemplation of nature and in communication with other living things, they become aware of some kind of force, or something, behind this apparent mask which we see in front of us, and they call it God."
When asked if this was the source of "the Force," Lucas confirms that his use of the term in Star Wars was "an echo of that phrase in 21-87." The idea behind it, however, was universal: "Similar phrases have been used extensively by many different people for the last 13,000 years to describe the 'life force,'" he says. "