Matthau Is the Answer to This ‘I.Q.’ Test : Movies: On location at Princeton, the veteran actor who plays Albert Einstein has a story for every occasion.

Time is relative, Albert Einstein said, so let’s say it’s summer. And you’ve traveled south on the Jersey Turnpike at better than the speed of light, evaded the troopers and the constraints of chronology, and found yourself in Princeton, which has a university and once had Einstein. It still has a university, but today it has Walter Matthau. And history seems to be in flux.

There’s a house behind us that dates to the 1770s, DeSotos in front of us that date to the ‘50s, some movie stars who date to--well, let’s not be rude--and a very ‘90s film crew that is shooting “I.Q.,” the Fred Schepisi-directed comedy starring Meg Ryan, Tim Robbins and Matthau as Einstein, and which opened at Christmas and was praised as the kind of comedy they don’t make anymore. But, again, time is relative.

It’s a typical summer day in Jersey. The temperature is thermonuclear and ticks are propelling themselves out of the weeds like rogue electrons. The scene at hand involves a presidential motorcade carrying Ike (played by Keene Curtis, who played Sam’s bete noire in “Cheers”) as well as Einstein, his fictional niece Catherine (Ryan) and Albert’s comical sidekicks, a trio of emigre scientists (Lou Jacobi, Joe Maher and Gene Saks), while Ed Walters (Robbins), fictional garage mechanic, tries to flag them down and propose marriage (to Catherine).

Robbins is supposed to be on a Harley, crossing the Revolutionary War battlefield that abuts the road, but as Robbins explained, “The insurance company wouldn’t like that.” So it’s his stand-in who’s astride the bike, which keeps stalling and prompts the rest of the crew to devise what Einstein never could: a unified field theory. Get the damn Harley across the field, or there’s gonna be trouble.

Their support is inspiring.

“Where’s the mechanic?”

“Slitting his wrists.”

“What’s he need, a wrench?”

“A gun.”

The bike runs, finally, popping, chugging and then rolling its way across the venerable turf--which an unscheduled jogger has decided to cross at the same time.

“Oh . . .” someone says, expressing the collective sentiment of the overheated. Yes, there’s glamour in the moviemaking process, but today it took a different exit.

Making light of the revered--Einstein, not New Jersey--has as many perils as a thunderstorm (which is on its way, it turns out) and can attract lightning. But while Schepisi, the Australian director of “Six Degrees of Separation,” “The Chant of Jimmy Blacksmith,” “Roxanne” and “A Cry in the Dark,” is mucking about with its icon, Princeton the village has responded well. The local liquor store, for example, gave everyone associated with the film a 10% discount.

“There were some people who didn’t like it,” Schepisi said of his fictionalized physicist. “But that’s treating someone as an icon beyond even that person’s desire. In fact, he’s very clear about all that. There’s no way he would let his house become a shrine; he thought things should be left as they are. Judging by his sense of humor, I think he would have liked the whole enterprise. What were his last words? ‘I wish I’d had more fun.’ ”

This is a statement of dubious historical merit, but is Schepisi implying that he’s giving old Al the fun he never had?

“Absolutely!” he laughs. “I’m giving him a second chance.”

Einstein is a beloved figure in Princeton, where he taught at the Institute for Advanced Study, and where he lived for more than 20 years. (The film is set just prior to his death in 1955.) Matthau is a beloved figure, too, in his way. When the motorcade and filming stop, he’s swarmed by autograph seekers and obliges each one.

“Thousands of children are screaming at me, ‘Mr. Wiiiiilson,’ ” Matthau says, referring to his role in the otherwise forgettable “Dennis the Menace.”

Back in his trailer, he looks like an aboriginal Oscar Madison. Undershorts, robe, no socks--”Einstein never wore socks,” says costume designer Ruth Myers. “This is an absolutely known fact”--and sandwich-box shoes. The basset-hound face is topped by wild white coif of Einsteinian disorder.

“It’s a wig, yeah,” he says. “My own hair, unfortunately, is very black. And it looks fake.”

Matthau is full of stories--about losing millions in antiques during the last earthquake, about playing Ping-Pong with O.J. Simpson at producer Richard Zanuck’s house, about having taught the unit publicist to bet on ball games. Some of his yarns are even about Einstein, about whom Matthau seems to have heard everything since arriving in Princeton, and Cranberry and Hopewell, and the other Jersey sites where Schepisi has been filming.

“One woman told me I was walking the wrong way,” Matthau says. “She told me, ‘This is the way Einstein walked.’ ” He gets up and demonstrates. “Another said, ‘Yeah, but you’re bending over too much, and he walked faster.’ ” He demonstrates. “Another told me, ‘He never wore shoes that good.’ ”

Matthau got a letter telling him about a family next door to the professor whose daughter was always visiting Einstein’s house. One day, the mother saw the professor on the street and told him to send the little girl home if she became a pest. “ ‘Oh no,’ he said, ‘Vee haff a vundehful relationship. I do her sums, and she gives me her cookies.’

“This is a well-known story,” Matthau says. “And I listen to everything, then I forget about it. The subliminal mind takes over, does what it wants to do. It’s fictional, anyway, so I can do anything I want. It’s like my wife, who just wrote a book called ‘Among the Porcupines.’ I told her, ‘It’s full of lies.’ She said, ‘Well, I’m a writer.’ It’s like her ex-husband, Saroyan, once said: He knew the truth, but he was looking for something better.”

It’s hard to imagine a better Einstein than Matthau, at least in a comedy. But isn’t portraying such a legend a bit daunting?

“I think about it,” Matthau says, “but it doesn’t bother me too much. I get a kick out of it. As soon as I put the wig on, everyone defers to me. I suddenly don’t talk so well--even though I’m about the same age Einstein was when he died. I’m 73, Einstein was 76, so it’s close.”

Closer, he figures, than is his co-star Joe Maher, a veteran character actor (his numerous roles include the monsignor in “Sister Act”). “He’s Irish and he’s playing a German Jewish professor,” Matthau says. “Every once in a while he tries to fancy it up and it comes out like Maggie Smith. I said, ‘Your character, he’s a German Jew who’s spent a lot of time in the north of Ireland?’ And he says, ‘Can you play Einstein a little shorter?’ ”