As I type these words I'm periodically switching to another window, in which a chubby woman sits on the fourth plinth in Trafalgar Square, applying make-up. She's occasionally shouting "morning!" at people. Apart from that, nothing's happening. Yet it's so compelling, I can't stop flipping over to look at it, even though I'm on deadline. Now she's texting. Now she's on the phone to someone. Now she's stood up. This column's never going to get written.

I'm talking, of course, about Antony Gormley's One & Other (oneandother.co.uk) the "public art" project in which people take turns standing on the fourth plinth for an hour. It lasts 100 days, so that's 2,400 people, each of whom has their 60 minutes of glory streamed live on the internet. There's also a weekly catch-up "highlights" show on the Sky Arts channel. It's Big Brother: Tate Modern Edition, essentially.

I say Big Brother: it's actually more like the good old days of Big Brother; the early ones when we were astounded to watch live footage of people simply pottering around in a kitchen. When the housemates were left to "get on with it" rather than dress as pirates and play party games every four minutes. The days when nothing happened and we didn't mind. That's what this is like, minus a Geordie voiceover.

Mind you, even though the "plinthers" have zero opportunity to form holiday romances or start racist arguments (what with being alone up there) they're equally - if not more - attention-seeking than your average BB housemates. Half of them have come in fancy dress. We've already had a man dressed as a town crier bellowing about his pub, a man dressed as a cat fielding texts from the public, and a woman who did the midnight-1am shift disguised as a giant pigeon, occasionally emitting a rather half-hearted "cooo" noise. (Her costume was particularly rubbish: she looked like the lead in an illegal Turkish version of Batman shot on a budget of 25p.)

In other words, it's "Britain's Got People". Except no one's judged or voted off. They get their full slot regardless. The comedy writer Dan Maier (a regular TV Burp contributor, fact fans) quickly defined a condition called "Twenty-Minute Sink-In - the point at which plinthers realise their idea will sustain nowhere near an hour". Andy Warhol was spot on: 15 minutes is just right. After that they start to visibly deflate. A mini-breakdown ensues. The town crier quickly seemed to turn on the passers-by, berating them for not asking any questions. No one's done a shit or started jerking off yet, but that's bound to happen before the 100 days are up. It's like a David Blaine stunt taking place for no discernible point. So just like a David Blaine stunt, then.

There's also no technological "public interaction" system in place, although you can go down there in person and shout at them. That happened a fair bit last night. Trafalgar Square's pretty rowdy at 1am. No one's thrown a bottle high enough to catch one yet - and hopefully they won't - but that's bound to happen before the 100 days are up too.

Every hour, on the hour, a cherry picker comes in to swap one plinther for another. Right now the chubby woman's now being replaced by - uh oh - a man dressed as a turd carrying a loudhailer. He's protesting that 2.5 billion people don't have a proper toilet. Or clean water. Ah, he's doing it for Water Aid. It's like the London Marathon for people who can't be arsed running.

Fifteen minutes have expired for turd man, so now he's gone a bit quiet. But he does, at least, have some props: a giant fish head, which he'll presumably get to in a few minutes. If you're applying to go on the plinth (which you can do, via their website), I'd recommend taking a good book, or at the very least a Nintendo DS. Or maybe a small video recording of the previous plinther to stare at. Because it's a proper time sponge, this. Dangerously hypnotic. Sod the Angel Of The North. This is brilliantly futile.