It is not known whether Marilyn Monroe ever met and spoke with Albert Einstein (and since the mysterious disappearance of her diary after her equally mysterious death, we may never know), but in their lifetime the opportunity was there.
Scripted by Terry Johnson from his own play, Nicolas Roeg's Insignificance imagines an encounter in a New York hotel room one night in 1953 between the two icons plus Joe DiMaggio (Busey), and Senator Joseph McCarthy (Curtis) - but only on one level. On another level, it elevates - or reduces - these 'personalities' (and what a lousy phrase that is) to mere avatars (the characters are deliberately unnamed), at once greater and lesser in status.
The title Insignificance is both apposite and deeply ironic; here, DiMaggio's net worth has been reduced to little more than a picture on a bubblegum card. Monroe too is reduced to her constituent parts of dress, hair, lipstick, wiggle and voice. By uncovering their insecurities and reversing their roles, the film brings into sharp focus received notions of celebrity, exploding the cult of personality.
Furthering the theme, there will be another explosion at the film's climax: Hiroshima in a hotel suite, in which 'The Actress' is burned to a cinder in seconds; a literal deconstruction of fame. Goodbye, Norma Jean. History informs the script, which in turn, shakes history upside down. As Roeg mused after watching Johnson's play for the first time, "These characters were mythic, not invented by any single person, not the public or the press, probably not even by the characters themselves." As played by Theresa Russell, Marilyn (a closet intellectual in real life), lectures a childlike Einstein ('The Professor', played by Emil) on the theory of relativity using balloons and a flashlight, while getting The Professor to show off his legs, in conscious parody of her own role in The Seven-Year Itch, the movie The Actress is seen to be working on in the film's opening.
History records that Monroe's then-husband, fading baseball star DiMaggio (played by Busey as a tenderly psychotic simpleton), was unhappy about her iconic dress-splaying scene in the film, precipitating their break-up. Right on cue, we discover the jealous 'Ballplayer' in a bar, bemoaning the fact that if, "I want to see her underwear, I just walk down to the corner like all the other guys".
In contrast to The Professor, The Ballplayer believes the universe is round - a contention shared by Native Americans. But the Big Chief (Sampson, of One Flew Over The Cuckoo's Nest fame) who operates the Roosevelt Hotel's elevator has been all but disenfranchised from his own culture: "I no longer Cherokee - I watch TV." Meanwhile, 'The Senator' is investigating The Professor, who is on the eve of delivering a pacifist speech to the United Nations, but whom The Senator suspects is a Red. In fact, as he divulges to Monroe, Einstein is wracked with guilt over Hiroshima, and what the white heat future holds. Yet in a seemingly godless universe, all such worries and aspirations are rendered insignificant in the light of a higher (atomic) power.
Roeg really is the perfect director to bring Johnson's stage play to the screen. Throughout, tortured childhood flashbacks and pessimistic flash-forwards (ka-boom!) draw unexpected connections between time, place and circumstance, with the repeated visual motif of a wristwatch employed to mark time's passing - but perhaps also to suggest all time is one time; each moment co-existing. As evinced by his back catalogue, it's something of a hobbyhorse for a director enchanted with the notion of synchronicity - see Don't Look Now in particular. Here, 1920 bleeds into 1945 and drip-feeds into the 1980s, a period in which another 'Actor' has taken on his greatest role as the President of the United States.
If all this sounds rather heavy going (quantum physics is surely involved), the execution is anything but, owing to Johnson's witty, zippy screenplay, Roeg's playful direction, opening out an essentially stagey set-up - and the cast themselves, who are on stellar form. Tony Curtis especially leaves denture marks in the wood panelling as the paranoid, impotent Senator, who is seen attempting congress with a Monroe impersonator (a real one, as opposed to Russell's), before being let down by his dwindling member.
Of course, Curtis once co-starred with the real Marilyn Monroe in Some Like It Hot, and whose embrace he memorably described as like "kissing Hitler". As Roeg commented, "Everything suddenly seemed connected... when the film began to take shape even the actors themselves seemed part of this endless linking." It all goes into the pot, to be boiled down and served up in new and fascinating ways.

After watching this on the MST3K episode, I have to wonder how many movies this film borrows from. It seems to combine elements of Logans Run, Farenheight 451, Final Sacrifice and at least several others. At one point I was really expecting Cris Makepease to call Lee Majors ROWSDOWER.
I wonder if the director has any clue how many holes there are in the plot. like the fact that, even though gas is unavailable, there is plenty of it in abandoned gas stations, and the stations are located close enough together to keep an F1 race car going all the way across the country.