Nic's own planet Hollywood

If you're shelling out for the Ritz-Carlton, which looms pompously over the south side of Central Park, you do expect to at least see a celebrity or two. Still, finding themselves in a lift with a nattily-attired Nicolas Cage is obviously an exciting moment for a couple of teenage girls, one of whom looks like a younger version of Jodie Kidd.

"Nicolas Cage" she mouths silently to her friend, adding "be cool." They both stare up adoringly while the star himself politely ponders his reflection and ever so slightly suppresses a smirk. He's clearly made their holiday. The doors ping open and we spread out into the lobby. "Oh. My. God. Are you sure?" we hear one of the girls shriek. "He looks so much older!"

I glance in the direction of the publicist and laugh nervously. Kids say the darndest things. Mercifully, Nic (as we're all calling him) seems to be already well out of earshot. A morning in front of the world's press would be enough to age anyone, and with my turn in his presence about to happen any hour now a teenager's bitchy take on his thinning hair is really the last thing we all need.

Or maybe he did hear and just let it roll off him. When we meet again in his hotel suite he's looking relaxed and he talks a lot about his ability to absorb criticism. From the film set bullies who, he says, teased him because of his famous name (he's actually a son of the Coppola dynasty) to Sean Penn, who famously declared that Cage was "no longer an actor", Cage seems coolly equanimous about his critics.

"Whatever Sean said, y'know he's a friend," he tells me, waving his hand. "I haven't seen him in a long time. I would say he's right. I'm not an actor any more. I am trying to do something else with the work."

That "something else" has divided critics and in truth Cage has had a strange career. On the one hand he crops up with worrying frequency in "worst movies ever" lists -- The Wicker Man and The Weather Man have made many top tens -- and is famous for eccentric performances which we will politely describe as "impressionistic".

On the other hand, he has taken daring risks with his role choices -- Birdy was a particular coup -- was a deserving Oscar winner for Leaving Las Vegas and retains the kind of box-office clout that enables him to "leave a lot of money on the table for a role I don't believe in".

Of course, he believes very much in the film he's promoting at the moment. Knowing is a sprawling fantasy sci-fi about the impending end of the world -- and having grown up himself in a lone-parent household he tells me he felt a particular affinity with the harried single father he plays in the movie.

Cage was raised mostly in southern California by his father, a literature professor, while his schizophrenic mother, Joy Vogelsang, spent much of his early life in and out of psychiatric institutions. It must have been tough for him, but he is touchingly loyal to her and even credits her with his talent for acting.

"My mother, God bless her, had her problems most definitely, but I've no doubt that because of her imagination and enchanted way of looking at things she gave me a great ability to use my own imagination. There is, I always say, a fine line between madness and creativity."

In his youth, this mantra seems to have been his starting point for a volatile, rebel persona that seemed as wild a performance as anything he's since displayed on screen. Inspired by the Beatles song Why Don't We Do It In The Road? he had sex on an LA street. He "totalled" his sports car. On a date at a fashionable LA deli he decided to "turn the volume way up" by hurling a ketchup bottle at a wall (it didn't go down well at the time but after he became a star they apparently thanked him for the publicity).

He describes this to me now as his "punk-rock period" and adds that he had a type of "emotional Tourette's" which made him lose all his inhibitions. He views all this as necessary -- an "outgrowth of his artist's temperament". I can't help feeling that that's not how the guy whose job it was to scrape the ketchup off the wall saw it.

It has been written that all this wild-child living got in the way of school, but unprompted, he insists to me that he most certainly did graduate from high school.

"I do need to be fair and say I did graduate. It was quite a difficult exam. It was called uh ... gosh ... the BEA exam, which required essays and an enormous series of questions. No wait, my GED sorry. So don't think I dropped out of high school. I didn't go to college however."

Got it. But surely education can't have seemed all that relevant when a career in the movies beckoned anyway? Cage tells me that the plan B was to "become a fisherman" which sort of gives you an idea of how much of a dead cert a job in the film industry was. His uncle once told him that "this (Hollywood) is our town" and in 1983 Nicolas would star in Rumble Fish, a movie directed, written and co- produced by Francis Ford Coppola.

Of course, he doesn't like people pointing this out and the received history of Nicolas Cage is that he adopted the moniker of a comic book character (Marvel's Luke Cage) because he was sick of people assuming that he was just some hanger-on brat-packer, tagging along with the likes of Charlie Sheen and Emilio Estevez.

"There was no sense that I would have an advantage," he still insists. "I felt more pressure -- I was constantly being teased about my name -- Nicolas Coppola. It's not nice having guys lining up outside your trailer making jokes that you're only there because you're the nephew of so-and-so. I realised I was going to work twice as hard as the next guy."

Despite the claimed lack of advantage, he did get a starring role in Fast Times At Ridgemont High with scarcely an acting credential to his name. His co-star in that movie? Sean Penn.

Despite the early leg-up, it's been written that the Coppola men subsequently had a tense relationship with Cage, especially after he became one of the biggest stars in the world. He himself has put it down to "Old Country jealousy" and even now he tells me the relationship is one of "a busy family who all do our own thing". Perhaps wary of reopening old wounds he adds, "but when we do connect, by email or what have you, it's positive".

If success was received ambivalently in the family, it worked wonders for his love life. While his star soared heavenward, Cage dated a string of beauties, including Uma Thurman, and had a son, Weston, now 18, by actress Christina Fulton. He married Patricia Arquette in 1995 and divorced her seven years later.

As he was an admitted Elvis fan, his spur-of-the-moment nuptials with Lisa Marie Presley (the divorce lasted longer than the marriage) were perhaps understandable at the time but, today, reminiscing at the Ritz, Cage cringes at the memory.

"Yeah, I have regrets about my marriages. In the south-west [of the US] where I grew up, we have more divorces than we have in the north-east and, if I had grown up around snowstorms, I would have learned how to confront the snowstorms of my personal life."

Today, he is happily married to Alice Kim, a former waitress. They have a three-year-old son, Kal-El, (named after Superman's birth name on the planet Krypton) and in true Hollywood style, Cage seems to have traded his tantrums and Tourette's for something more sensible.

"My day to day life now is about playing with my young son and having nautical adventures with my older son," he tells me. "I have dinners with my wife and read my books. All that other stuff (the early wildness) tends to subside with age."

I'm hoping this is a mere build-up to a flash of the old, mischievous Cage but his demeanour today is much in line with his outfit of sports jacket and jeans. As his lugubrious drawl trails off, the publicist is hovering. My time is up with Cage.

He walks out with me and makes small talk on the way out onto the corridor, asking where I'm from, how long I've been in New York. It's an endearing little gesture. Most stars of his stature don't even shake hands.

On my way out of the swankiest hotel in the city I see the same two girls prowling the gilded lobby, cameras in hand. They've obviously thought it over and realised that while their friends will die when they hear they've met a big star, they also need proof. Nicolas Cage may not be boy-band-pretty up close, but he'd still better be cool with signing an autograph or two.

'Knowing' is in cinemas from March 25

- Donal Lynch