In a different forum, I would like to have asked what led John Travolta to play his 9-foot, 572-pound, dreadlocked, scuz-toothed monster in "Battlefield Earth" as an alien diva. (Ten minutes into the screening, the guy sitting next to me asked, "Is he doing Bette Davis?" "No," I replied, "Katharine Hepburn.")

In the eardrum-shattering piece of Manichean bombast that is "Battlefield Earth," Travolta carries on like a refugee from the "Outer Limits'" Ivy League who can't believe that he landed such a grungy, low-prestige job as chief security officer on Earth -- and is nonetheless determined to bring it off with impeccable hauteur.

Travolta was doubtless patterning himself on imperious movie villains from war films and espionage flicks, but what comes out is more like a New Jersey boy's playground impression of a New England snob. Yet in this cushy phase of his career, when he can carry even a screeching turkey like "The General's Daughter" to box-office success, Travolta operates with the press like an alien diva himself. He jetted into San Francisco, where his people arranged 15- or 20-minute group-grope interviews for him.

Midway through my session, which included eight or nine Internet and radio reporters -- someone asked the crucial question. He wondered whether the actor, producer and prime mover for the film version of L. Ron Hubbard's sci-fi novel, "Battlefield Earth," was upset by widespread rumors that the film would turn out to be propaganda for Hubbard's Scientology belief system.

Travolta responded that he found such advance buzz "funny, because it's so not what it is. Fortunately there are a lot of literate people in the world who know the difference between science fiction and philosophy, and clearly separate the two." He said he actually enjoyed some of the way-out conjectures, especially the one that the film would contain "subliminal" messages. "It didn't work for Pepsi," he quipped.

At the same time, he didn't want to limit people's perceptions. He called "Battlefield Earth" an "entertainment piece," with "no particular message, other than how big is your popcorn or your candy bar." But then he said, "That's what good movies do, they provoke thinking of some sort," and compared the questions audiences might have after seeing "Battlefield Earth" to those they had when they wondered what was in the briefcase or under Ving Rhames' Band-Aid in "Pulp Fiction."

In my personal minute in Travolta's spotlight, I asked whether he'd worked on the script for "Battlefield Earth." He said he didn't need to. "[Screenwriter] Corey Mandell loved this book -- we finally found the right writer. He really adapted it well. All the great points of the book he got down. I don't think I altered anything of his. That for me is completely unusual. I'm [usually] like, 'Oh, he wouldn't say this ...' I'm like all over it. In this particular case, I wasn't; it was like, 'Oh, this is great.'"

Was it fun, I ventured, playing the most educated character of his career? "He's educated in his own mind; he's a legend in his own mind," he said. "I love when he's at the table with his senior [officer] and he's like, 'Aren't you aware of my academic achievements?' He's so full of himself it's just delicious."

And did his experience in Hollywood make him enjoy the concept of his alien character always trying to gain some kind of dirty political "leverage?" "[That applies to] Hollywood, Washington -- that's why I think it's so much fun, it's so identifiable. The whole leverage background was hilarious."

As he shook hands with everyone and flashed a flood-lamp smile on each questioner, you got a sense of the piercing sweetness that first made Travolta a star. He was genuinely thrilled that the packed house the night before had given this film hearty applause. (Of course, it had also cheered for Hubbard.) After breaking the ice, there was little time to do anything more than churn up the shallows.

A Travolta fan since "Carrie" and TV's "The Boy in the Plastic Bubble" (both 1976) and "Saturday Night Fever" (1977), I worried that this now-beefy, always-beaming baby boomer, who hasn't given a great performance since "Get Shorty" six years ago, had fallen into the same syndrome that plagued him in the early '80s, when he said, "I got fat on success." Some actors, like Orson Welles, come into their own as performers when they let everything hang out. But with the bulkier Travolta, as with the even bulkier Gerard Depardieu, I think an air of self-indulgence gets between the audience and the robust sensitivity that used to be his gift.

You couldn't conceive of "Saturday Night Fever" without Travolta, and he was the heart and soul of Brian De Palma's masterpiece, "Blow Out." His career, like De Palma's, might have been richer if "Blow Out" had been a hit. He relaxed into the role of a limited technician with unlimited feelings and found more screen depth than at any time before or since. By contrast, his comeback role as a hit man in "Pulp Fiction" had an aura of camp, and the joke behind his sensational turn in "Get Shorty" was that he played a hit man like a movie star.

Maybe at this stage in his life and career, it's easier for him to draw on movie-bred experience. He did respectable but dull work in "A Civil Action," and from "Broken Arrow" to "Battlefield Earth," he's gone further and further into absurd stylization. All you can say about his performance here is that it gives the movie the only oomph it has.

Yet Travolta said he's tickled to the bone by "Battlefield Earth," both as an actor and a producer. "It was like four hours of makeup," he told us. "The process of it wasn't bad, it was after -- the claustrophobia and the heat of it. But every little trick added to my potential evilness, so it was fun on a certain level."

He grooved on his vaguely Rasta-esque get-up and amber eyes and the extra talon on one of his hands. "The teeth I added -- you know, they drink this kerbango drink, so I said, 'These teeth should be funky, because they're buzzed all day on this drink.' We're all coffee drinkers and iced-tea drinkers, we all get bad teeth; I'm sure kerbango messes with their teeth. I said, 'Bring it on.'"

On his own Travolta scale of comic-book villainy, he said "Pulp Fiction" was "more subtle," "Broken Arrow" was the start of his "new theatricality" and "Face/Off," his huge hit for John Woo (who'd also done "Broken Arrow"), "went over the top." "Battlefield Earth," he said, went over the top of over the top: "The get-up invited me to have a blast, to get Shakespearean, almost. The dialogue I love. Every day, I couldn't wait, it was delicious to me to say those words: 'Well, I can see someone like you, being old and having no future.' Remember, to the man with the double-chin? It's just delicious. Or when he's at the bar and the bartender doesn't want to be blackmailed, and he says, 'You better start thinking about it. I'm not your friend!'"

If those lines don't particularly resonate on the page -- well, they don't in the movie, either. For an actor, believing in your material no matter how lowly can be a plus. But when that actor becomes a producer-star and tries to impose his own literary standards, one can see it scaring away potential heavyweight collaborators. A sci-fi fan asked why, if Scientology had nothing to do with the making of the film, Travolta didn't get behind a bona fide sci-fi classic like Alfred Bester's "The Demolished Man" or Robert Heinlein's "Stranger in a Strange Land."

"'Stranger in a Strange Land' I would like to do," Travolta said. "People for years told me that it should be done. The reason this was easier was because a) I was very popular playing a villain and b) it's such a big book recently -- 6 million copies sold worldwide. And it's more along the 'Star Wars' style of special effects, so I think it was an easier task than 'Strangers in a Strange Land.'"

Travolta said that he has been trying to make the film for 18 years -- but that he originally had the idea of playing the hero. "I got long in the tooth, teeth got dirty, I got heavier," he said with a smile. "I do think that a younger guy -- [the hero] was kind of written for that, it was righter for Barry Pepper. And interestingly enough, the timing made it work because with all these other villain parts I played, it seemed like a perfect challenge to do a new kind of villain."

With the movie's blend of computer graphics imagery, miniatures and full-scale props, "The technology caught up with this book in a way. I don't think 15-20 years ago there would have been the same possibilities." Travolta said that he's nurturing no other dream projects.

"After 'Pulp Fiction,'" he explained, "there was all this brouhaha about my performance there, and it had been almost 20 years since 'Saturday Night Fever,' and I thought, 'All right, what do I do next. People are so excited about my performance, what do I do next?' And then suddenly scripts fell in front of me that I hadn't had before, like 'Get Shorty,' 'Broken Arrow,' 'Michael,' 'Face/Off,' 'Primary Colors,' 'Civil Action.' I never dreamed of playing those kinds of parts, I just knew I could."

And Travolta said he has no master plan for his career, beyond extending it as long as he can. "I don't ever think there's that day when you say, 'Oh, that's it.' I think age-wise there might be. I think Jimmy Cagney, after 'One, Two, Three,' he just said, 'OK, I'm 61, that's it.' Pilots retire. Would I retire? I don't know if I'd be capable of doing that. I like performing too much."