MARILYN MONROE is a goddess. Albert Einstein is a genius. Joe DiMaggio is a hero. Joseph McCarthy is a villain.

No past tense for these cultural icons. With the possible exception of McCarthy, they continue to live in an eternal present, their stature growing with successive generations. No ands, ifs or relativities about it--this unlikely quartet looms larger than life in the consciousness of Middle America.

But that of course does little to explain what they are all doing together, wandering in and out of a Manhattan hotel room on a steamy summer night back in 1953--the setting of Nicolas Roeg's latest movie, the self-consciously significant Insignificance.

The premise is irresistible. Screenwriter Terry Johnson has adapted his London stage play, combines star-struck childhood fantasy with that most basic, and base, of human impulses--reckless voyeurism. Yoking together the competing myths of his protagonists, he unleashes them on unsuspecting viewers in a bizarre kind of Battle of the Network Stars.

Inevitably, and with allowances for the sexual revolution, Marilyn wins.

In fact Theresa Russell's pouty, luscious incarnation of the blonde bombshell is about the only reason to stay with this film after the novelty of its first half hour wears off. As Marilyn in her pre-platinum youth, Russell looks more like Kathleen Turner than Norma Jean Baker, but what's a little makeup among sex symbols? Besides, she so dominates her every onscreen moment that it's difficult not to chastise the superhumanly chaste Einstein for declining her offer of a roll in the hay.

Unfortunately, Roeg's mythologizing of the four characters succeeds only with Marilyn. Perhaps he has been reading Norman Mailer, for he, too, sees her as more than the apotheosis of sex appeal. The woman who once sang "Diamonds are a Girl's Best Friend" and died of a mysterious overdose comes to embody maligned femininity everywhere. Treated as a sex object she resigns herself to scoring all her points by means of sex. She is forced into a role that suffocates and ultimately kills her.

INSIGNIFICANCE starts off with, well, a bang. Roeg (The Man Who Fell to Earth, Performance) opens with a tantalizing series of shots: The Actress (names are no more specific--this is, after all, a fairytale) prepares to shoot the famous skirt-blowing scene from The Seven Year Itch. Bystanders leer and sigh, particularly a vaudvillian duo manning the wind machine beneath the grating.

Also on the set is the Ballplayer (Gary Busey), jealous Jolting Joe, who simmers and frets and generally acts betrayed. The man who has come to represent genial Mr. Coffee is nothing but an oversized gum-chewing adolescent, as idiotically captivated by his own fame as are his fans. The big brute is more than just a moron, he's an oxymoron.

Meanwhile, perched several stories above them all, on a planet of his own invention, the Scientist (Michael Emil) fumbles among stacks of yellowing papers that contain the secrets of his final project--a theory unifying the fields of nature.

This Einstein sports a Princeton sweatshirt and keeps having flashbacks; Roeg clearly enjoys using them. His apparent guilt is hammered home repeatedly, but it never becomes credible. We learn, to our disbelief, that Einstein blames himself for nothing less than the dawn of the nuclear age.

Enter the Senator (Tony Curtis), who badgers the scientist about attending a Congressional hearing. Curtis plays his role to the hilt and turns in an energetic performance in his most substantial part in years. Nevertheless, the part is all wrong, torpedoed by amateur psycho-speculation about the Commie basher's alleged impotency.

After the initial voyeuristic thrill, Roeg's farce runs out of gas--and not only for lack of good lines. Unlike Tom Stoppard's dazzling Travesties, in which James Joyce and Lenin cavort without losing dignity, this film offends the myths it pretends to revere.

The spoke in Roeg's elaborate practical joke lies in the fact that Insignificance backfires at precisely its most seductive point: it makes us feel guilty for our curiosity. First we are encouraged in a galloping case of Peeping Tomism, then we are slapped on the wrists for expecting anything but coy, hyperventilated fluff.

Disappointed viewers would do better to stick with the tabloid version: "Vamp gets Bopped by Pol as Slugger, Time/Space Physicist Look On."