But the interviews were never screened and the collective thoughts of 21 eminent men and women of science appeared to have been lost for ever.
Now the musings are to be made public for the first time when they are published next month, giving Kubrick enthusiasts an insight into his ultimate vision for the classic film.
A recluse who died at the age of 70 in 1999 shortly after the completion of his film Eyes Wide Shut, Kubrick had a lifelong fascination with the possibility that there was intelligent alien life. He wanted to share his belief with the audience as a scene-setter for his film by allowing them to hear the scientists' own words as they discussed the possibility of benevolent alien cultures, the origins of life and the future of man.
The interviews, conducted in 1966, reveal the thinking of many of the eminent scientists in an era when man had still to walk on the moon.
Among those who contributed were the writer and academic Isaac Asimov, the anthropologist Margaret Mead, and the astronomers Fred Whipple and Sir Bernard Lovell. All agreed on the likelihood of there being intelligent life on other worlds, while some spoke of the possibility of genetic manipulation and the development of "ultra-intelligent" computers that could possess personality traits.
The leading mathematician Jack Good suggested the next stage in human evolution could be the possibility of telepathic communication, an idea accepted by Kubrick at the end of 2001 where the human body becomes redundant.
Another interviewee, Constantine Generales, suggested the idea of the internet. The physicist Freeman Dyson proposed that we might one day colonise comets, and Asimov spoke of colonies on the moon, Mars or Jupiter.
But even for Kubrick, not known for the brevity of his films, it became clear his masterpiece would be far too long unless the sequence of thoughts about the future was cut. The US-born director had built up an enviable reputation with hits such as Spartacus, Lolita and Dr Strangelove, but 2001 was a challenge to many cinema-goers when it was released in 1968. Although dazzled by the artistic vision on-screen, which influenced numerous other sci-fi films, they found the film difficult to interpret.
Arthur C Clarke, who co-wrote 2001 and inspired it with his short story Sentinel, has admitted: "If you understand 2001 completely, we failed. We wanted to raise far more questions than we answered."
Kubrick, who wrote, produced and directed his films, was intrigued by the possibility of other life forms, but was disappointed the film world had until then tackled science fiction by portraying blood-thirsty monsters attacking the earth.
His long-standing assistant Tony Frewin, who worked with him for 25 years, said: "When the pre-production of 2001 began in 1965, the position of science fiction in cinema was pretty much that idea of Flash Gordon, Buck Rogers, bug-eyed monsters and Mars Attacks. When Stanley decided he wanted to make a futuristic science fiction film about the existence of extraterrestrial life it worried him people would see it as just a bug-eyed monster film.
"So what he decided to do was interview 21 professional scientists for a prologue to show that considering whether there was extraterrestrial life was a legitimate scientific question. Before then, if you spoke of extraterrestrial intelligence people would have simply said 'what, flying saucers?' and all that nonsense. But the film got longer and longer and he realised there wasn't going to be enough time for the prologue, and the film would have to stand on its own two feet, so it was eventually nixed."
Although long discarded, Frewin wanted to trace the film for a DVD release of 2001, but despite a lengthy search was unable to find any trace. He believes it probably still exists, perhaps mislabelled and sitting with miles of other film reels in a laboratory.
"Stanley wouldn't have given it away and he wouldn't have destroyed it. He never threw anything away. He still had chequebook stubs going back to the 1940s," said Frewin.
However, during his search, he found the transcripts of the interviews that had been prepared by Kubrick's secretary, Vicky Ward, to help him in the editing suite. Frewin has now edited them for a book of the complete interviews to be published next month.
Some of the interviewees have looked back at their original comments. Professor Good stood by his, including his suggestion that computers might have personality traits: "My Windows 98 computer tells lies and often forces me to shut down improperly. Such behaviour in a human would be called neurotic."
One absentee from the list of interview subjects is the astronomer Carl Sagan, who went on to find fame as the author of the book Cosmos and a spin-off TV series. He responded by saying that he wanted editorial control and a percentage of the film's takings, which was rejected.
'Are We Alone? The Stanley Kubrick Extraterrestrial Intelligence Interviews' are published on 8 November by Elliott & ThompsonReuse content