PC Hewson and his balding guitar-playing mate find it all a bit laughable. In fact, they'd rather not talk about it; unfortunately, world domination and this "Pop" business they're about to launch does need to be put in some kind of context. After all this is U2 and March 3 will be Monday Bloody Monday in the ongoing saga of maybe the greatest argument that ever echoed down the windy halls of rock's pantheon of opinion.

The verbal and philosophical stoush has been on for ages - 12 or 13 years, perhaps. Simply put, U2 are either the saviours of rock'n'roll, the single most important band of the past two decades and one of the very few capable of turning the contemporary muse on its generally flat ass or the exact antithesis of that: a self-serving, self-ingratiating, bombastic, over weaning mix of twee socio-political and aimlessly passionate dreck posturised in any number of over-produced musical disguises.

And, of course, the man who was Mister Macphisto and the man who's always been The Edge are right: it's as fundamentally daft and overtly serious as the argument is pointless. What rock has always needed - and relied upon - is bands capable of lighting the fuse, sufficiently talented to take the raw stuff of any time and give it a tweak that sends the ordinary running for cover and the aware off thinking about how exactly they can take that spark and light their own unforgettable fires.

When you get right down to it U2's music is and has always been primarily about the search for God and the spirit's struggle to articulate its immortality within the very framework of man's own simple mortality. It's a forum and pulpit for age old questions: the conflict between spiritual longing and worldly desire, moral grace versus comfort, soul versus flesh. And in the coolly agnostic world of rock they are high ground, high culture.

It is the very reason why U2 have so polarised the world and the very reason why they are so damn successful and so damn important: rock's responsibility to at least point generations in some direction, open the mind, ask the big questions and equally let the good times roll. What makes U2 great is their ability to do both and that, in turn, makes this Irish quartet the quintessential rock'n'roll band of their time and a target for every emotion, desire and expectation we can throw at them.

This is, after all the band that has already redefined rock twice, perhaps three times: certainly with "The Joshua Tree" and "Achtung Baby" and also it could be argued with "War" or "Unforgettable Fire". All of which makes "Pop" the most important record of 1997.

So let it be said that with the Flood/Howie B produced "Pop" U2 have delivered an album that once again does that "something" for the contemporary muse: spooks it right out of its listlessness and general inability to decide which direction - if any - to embark upon, and in one stroke of sublime genius takes the essence of rock, pop, techno, drum'n'bass, ambient and jungle and fuses, melds, caresses it into a new shape. Not dramatically but subtlety and sublimely. Pop is going to scare a lot of people, and throw a curveball in the face of predicability. A record of the '90s for the '90s.

Its creators, meanwhile, seem much the same as ever; a little more grounded than last they strode the world stage with the manifestly religious Zoo tour and Bono's Macphisto persona: the devil inside. If there's a difference it's in their own rejection of the technology that so dominated "Zooropa": frankly, they admit they lost the plot a bit. Larry Mullen summed it up straightforwardly recently when he said, "A lot people are saying, have you become dance or trip-hop? You hear all these terms used. I'm not comfortable with any one particular genre of music, I just like the idea of taking whatever is out there and fucking with it.

"It's very easy to just lose what's special about a band through technology, and we've touched on that a couple of times. 'Zooropa' was the start of it and we got away with it, but in 'Passengers', we were just about to cross over into an area that I wasn't comfortable with. So this record was actually an opportunity to take it back to ... there's no word to describe it as such. But I am concerned about these reference points. It's a load of bollocks, we're just messing with different things."

Throw that line at The Edge, over the years as easy as anybody in U2 to chat with, and he puts it in a nutshell, "With this record, there was a lot that we were trying to take on. We wanted it to be a record with some real songs, some discipline and some focus in the material. We also wanted to take in some new ideas from the world of dance music and hip hop, or whatever, because we felt strongly that that's where music is at its most interesting at the moment. So, a lot of the time, it was really about finding our way into these worlds of trance and techno and hip hop, and learning how we could operate in those worlds, then integrating it back into the songs we'd started to write. So there was an awful lot to pull off on this project."

And pull it off they did: perhaps the key word in it all is songs - and that sense of the big questions. The U2 for 1997 evokes the essence of The Joshua Tree - one of the defining records of the '80s - and exactly a decade later, as Bono says, has delivered its logical extension.

It's scope is vast: on Mofo, they mine the essence of Underworld and Prodigy yet fall away in the middle to allow Bono's vocals to float, haunting, over a distant atmosphere, whispering to his mother "now I'm still a child" and end on an outro that is simply breathtaking; by contrast the following If God Sends Us His Angels is to use the Edge's description country hip-hop and it's blindingly gorgeous. A velvet crush of a song in which Bono whispers "nobody made you do it, nobody put words in your mouth ... " And if its essence is accountability so too are U2 throughout Pop. And the Edge's spiralling, picked chords just float off.

Welcome back, the Edge: a hallmark of U2's best has always been that glacial, ethereal guitar; on Pop it's a distant sun that floats through the mix, colouring the textures built around Bono's best vocal performance in years and a bottom end that works some extraordinary magic with Clayton and Mullins running their bass and drums against one another, shaping impossibly demanding polyrhythms as a bed on which to colour a shifting spectrum of sound.

Staring At The Sun is psychedelic-edged pop that's already drawn comparisons to the Kinks and Bowie's Soul Love. It's single bound at some stage. Last Night On Earth is classic U2 rock, a return to the sense and sound of Unforgettable Fire and The Joshua Tree, updated by a cool, spacey groove that gets all edgy in the middle and bites back at the song before working back into the main chorus and verse.

It's a technique U2 use throughout the album - shifting the middle ground into cut out beats, strange textures, slowing it down, spinning out, allowing trip-hop/hip-hop guru Howie B room to mix it up - but now they, unlike Zooropa, don't forget the song.

The Edge considers his role in all of this, admits that right now the band is still way too close to "Pop" to really understand what they've done. "I definitely went into this project wanting to play more guitar for a number of reasons," he says. "Firstly, because I thought I'd played so much keyboard on 'Zooropa' and even the guitars on that sounded like keyboards, so it was time to move back to the guitar again.

"I also think the guitar has been kind of coming back but it's been coming back in a very straightforward way and a very retro way and I thought that there was an opportunity to use the guitar but push it forward. To actually try and find new things to do with the instrument and that this would be a good time to do it...

"Since everyone is going in that direction I just wanted to go the opposite direction and when you do that you often find you're in some very unusual and unchartered territory and that's, from my point of view, the best place to find yourself because your solutions are always unusual solutions and you find inspiration that way."

Bono laughs, "What he was saying before about the music though is true. We wanted the music to have vitality. We wanted to make something fresh. Something that, there's a surprise there like there should be in rock'n'roll. There should always be a surprise and there was a time when people heard like Jimi Hendrix for the first time and there were sounds and noises and feelings that no-one had heard before.

"We felt that rock and roll had gotten too safe and people knew what the sound of a Marshall guitar was when it was turned up to 11. There was no surprise to it, so we had to try and start again and find something fresh which entails, really, breaking up the band and starting again which is what we did for the 'Unforgettable Fire', which is what we did for 'Achtung Baby'. You have to keep it interesting for yourselves if you want to make it interesting for other people."

The Edge carries on working laterally off Bono's references, "I think on this record, maybe because we spent a year away from one another and a year exploring what was going on out there in New York, in London, wherever we were, I think we feel more part of what's happening. It's like we were writing this record from the inside as opposed to other records where we had a sort of perspective of what's happening.

"I think there seems to be a lot of themes that are common and one is the moment, where it's like just live it." Bono nearly interrupts but holds back as The Edge continues, "Don't think too much. Just live it and in a weird way as we went through this record and wrote these songs with that spirit we found ourselves coming right the way back in full circle. Of our most recent records it's the one I feel is closest to what's happening out there. I think this is what people are thinking about. It's certainly what we've been thinking about. Again, that just happened. That's where this work has led us."

This is really the core of what all the fuss in the next few weeks will be about. The creative process for "Pop" is similar to that for "The Joshua Tree" and as Bono pointed out "Unforgettable Fire" and "Achtung Baby"; somewhere in all of this is an equation which makes U2 recurringly and increasingly great and you sense that it fascinates both men as much as it will the listening world.

If there was a patented formula for reinvention, it'd be a damn sight easier for everybody but the creative spark is an ever-changing flash in the night and its inconstancy is the precise reason why progress is possible.

"Yeah, that's interesting," says The Edge. "I don't think we are the band that could recreate something really because for us music is something that's so much to do with the time that once you've done it, it would be impossible to kind of go back. I think the truth of it is that whenever we go in to make a record, we always go in to make the same record. It's just every time it comes out differently for a number of reasons. First of all because we're listening to very different music and being inspired and turned on by different things and because we're different people.

"We've seen, learnt, heard so many more things in the interim period that have interested us that inevitably we come out with different things and also we forget the things we did know. I mean I would love to be able to sit down and write tunes like we wrote on the 'Boy' album but I've forgotten how. That sounds very glib and throwaway but in some ways there's some truth to that.

"You know I listened to some of the earlier records not so long and I thought 'wow there are some fantastic ideas there, some really great things going on' and how the hell did we come up with those. I have no idea, no memory, recollection of coming up with that music so I don't think we could recreate anything really."

For Bono the answer is simple: "It's about keeping it interesting for yourself. That's really what we're about and whatever rock'n'roll is - and I'm not sure what it is - it seems to be about the moment and being in that moment and what we're trying to do with this record is take all the ideas that are in the air, you know, musical or even just what's out there. You know, what people are thinking and just try to put it all into one record. I'd like to think that in U2 there are lots of different colours and different feelings and that's what a rock'n'roll band has to do now."

So, gentlemen, to end, describe 'Pop' and why, for that matter, is it 'Pop'? Apart from the fact that it'll catch on, it's damn easy to market, has tons of possible run-offs and run-ons, and loads of meanings.

They've, of course, figured this one out by now, but the answers are refreshingly multi-faceted. Right now, the general impression is that U2 are quite happy to be back and working it again.

"It sounds fresh cause it is actually fresh," The Edge says. "It's not over worked. In fact, it's our most diverse record ever, sonically and in terms of the influences and in some ways that's why the title 'Pop' seems somehow appropriate at the end is because it's sort of a broad term. It doesn't really tie you down to one style, one idea. It's quite open.

"The only consistent factor is that it's music that's of the moment and I suppose in some weird way that's what we were trying to do, was to produce a record that just was very immediate. It crystallised a moment for us in our own music and also referencing music that's going on around us because I think all the influences, musically, for the record were quite contemporary things and things that could describe pop music in the '90s.

He pauses, and concludes slyly, "What we mean by pop music of the '90s is maybe not what everyone else thinks but it's pop to us."

Bono adds the footnote: "Everything is very different on this record. So we're just really, we're greedy, we want everything for our band. We want to be the loudest, we want to be the poppiest, we want to be the funkiest, the freakiest, you know, we want everything for it. Some of the songs on 'Pop' are just very straightforward, simple, you know just the band playing. And some of them have me dressed as a policeman."

PC Hewson and his guitar playing mate start nattering about how this and that will work on stage when the bigger-than-Zoo, PopMart world tour kicks off in April; after all they have to consider how the hell all this going to pan out in a setting that will boast the world's largest video screen, a 100 foot high Golden Arch, a 35 foot high Mirrorball Lemon and a 12 foot wide illuminated stuffed olive on a 100 foot tall toothpick.

"You now, it really costs a fortune to look this trashy," quips the enforcer. "I think the tour will be equal parts kitsch and content. We just figured out that we're still the bleeding heart's club; that's the truth. Our music is painfully, insufferably earnest. We've just got really smart at disguising it and throwing people off that trail."

Or, maybe, if truth be told, putting them back on it. On "Pop's" extraordinary Americana/Spaghetti Western closer Wake Up Dead Man, he sings "Jesus help me, I'm all alone in this world and a fucked up world it is too/ Tell me, tell me, tell me the story, the one about eternity and the way it's going to be ..." Redemption, hope, possibility. U2 have finally found what they were looking for. Again.