William Basinski has built an international career from his glacial meditations on time and decay, including The Disintegration Loops, which are regarded as perhaps the definitive artwork made about 9/11. To look at him, shirt open and hair slicked, Tommy Lee Jones handsome, he appears to have slowed his own mortality down along with his tape loops and samples.

Basinski was born in Texas in 1958, and says his earliest “really mystical, wonderful, magical” musical experiences came as a baby in Houston’s Saint Anne’s Church. We’re sitting in another church, St John on Bethnal Green, London, where Basinski has just played a set with fellow ambient composer Lawrence English – drifting, reverberant chords with the tiniest feather tickle of rhythm from a tape loop.

“Churches are musical instruments,” he says. “They’re incredibly sophisticated machines.” His Catholicism, though, has lapsed. “I don’t believe in what passes for Christianity in my country, at least these days – it’s horrifying. But I do love Christ, and everything he stood for.” The vicar pops in to say thanks for the performance. “We do what we do on a Sunday morning, and you do what you do on a Friday night.” Basinski laughs and puts him right: “No, it was a mass, believe me. I was praying the whole time.”

Basinski performing at St John on Bethnal Green, London, in March. Photograph: Christian Sinibaldi/The Guardian

Basinki’s rejection of Catholicism is understandable. He knew he was gay from an early age, after the family moved to Florida. “I was already a very flamboyant little hot mess of a kid, getting beat up,” he says. “There were a bunch of mean, mean, mean kids in Florida.” A perceptive junior high teacher channelled Basinski’s artistry: “A very nice man, Mr Wood. He was terrific, and he decided I was going to be the first chair clarinetist and the student conductor and the drum major.”

His father worked as a scientist contracted to Nasa (“he once took my hand and poked Neil Armstrong in the butt”), which made for an itinerant childhood. After a move to Dallas, Basinski ended up playing in a 300-piece marching band in high school, and in a symphony orchestra and a jazz band. No good at auditions, he was happy at third chair. “I could get stoned before school and not worry about solos. They wanted me to be first chair clarinet at New York Philharmonic, and I wanted to be David Bowie, so it was, this ain’t gonna happen, girl!”

Nevertheless, he kept playing, improvising at home. “Edgar Winter was an idol of mine with the saxophone – I could slow his records down and learn the solos. And the blues really struck me, because I had the blues as a child. I was melancholy.” He went to North Texas State University (now the University of Texas) in Denton to study music, majoring in composition after flunking out of jazz band. “Most of the major music schools were still about 12-tone serialism, which I had done. I enjoyed the math and difficulty of it, but it wasn’t what I wanted to do. It was too world war two.” Instead, he was being creatively turned on by the new school of mid-century minimalist composers. “John Cage, Steve Reich and Brian Eno were this golden triangle that gave me permission to try anything I wanted.”

‘I thought, use the time, you fucking idiot: get back in the studio and back to work’ ... William Basinski Photograph: Christian Sinibaldi/The Guardian

Surrounded by Denton’s “queers and fabulous artists”, Basinski had finally found his tribe. “It was when The Rocky Horror Picture Show came out, and these people had all the costumes. Girl, I was like, hello! Makeup? Stilettos? Count me in! Glitter and pretty stuff and vintage clothes galore – are you kidding?” He met the man who remains his partner, artist and curator James Elaine. “He was like the king of the art world there,” Basinski remembers. “When he first came into this coffee shop, he ignored everyone else and started talking to me, which made everyone really pissed off. ‘Who the hell does she think she is?’ I found out a couple of years ago he was stalking me. He knew my little blue Volkswagen. And he got me.”

His wistful sigh suggests this was rather more romantic than the word “stalking” implies. “He was my master, my mentor. We would go to museums and see Clyfford Still paintings, to rundown theatres to see Godard films.” Basinski dropped out, and, with money he had made as a nude life model, bought a plane ticket to join Elaine in San Francisco. What’s been the key to their lasting relationship? Basinski cackles. “For the past 20 years we’ve lived 3,000 miles apart most of the time!” (Elaine is based in Beijing.)

Indeed, Basinski’s biggest success would come after he moved to New York. He knocked about there for years, producing bands (“the record industry ruined everyone I practically gave them, the fuckin’ idiots”), and occasionally playing in them, once opening for David Bowie playing sax with rockabilly band the Rockats. He lived in a loft in pre-gentrification Williamsburg, where he later owned a vintage store. He made music throughout, but releases were rare.

‘It was almost like the core of this melody was trying to hold on ’til the very end’ … Basinski. Photograph: Danilo Pellegrinelli

Come 2001, Basinski was “basically at the end of my rope. I was broke, about to be evicted; my shop had closed. I thought, use the time, you fucking idiot: get back in the studio and back to work.” He reached for some raw compositional material: hours of recordings of a muzak radio station he’d made in the 1980s, using old tape equipment “designed for guys to get laid: you would record all your favourite ‘I’m having a date over’ albums, on a slow speed so it could go for hours and you wouldn’t have to be interrupted to go change a record.” He rejects the dismissal of muzak. “It was like anaesthesia music. Before Prozac there was muzak,” he says. “But when you slowed it down, like looking into a microscope, there’s this huge well of melancholy there.”

Basinski began digitising the old tape loops, but bits of the tape’s metal surface starting flecking off. As the tape loops circled, disintegrating more each time, the mournful muzak melodies broke up. “It was almost like the core of this melody was trying to hold on ’til the very end. That was profound.” He recorded more and more old loops, each of them disintegrating. “In two days I had this five-hour extraordinary masterpiece.”

Basinski and his peers – including Anohni – listened to the recordings throughout August, “tripping out”. It was still a glorious summer come 11 September 2001, “an extraordinary, crystal-clear day”. Basinski saw the first tower fall from his bedroom, the second from the roof. “I had a job interview at the World Trade Center that day, for an arts organisation who had offices on the higher floors. Administrative assistant. Luckily for those kinds of jobs, the interview isn’t at 8 o’clock in the morning, it’s at 11, and by then the buildings were gone.”

What was it like, seeing the towers collapse in real time? “It was a shock and a horror, and it got worse and worse. We all knew, oh, great, here we go, the greatest show on earth, armageddon. Steel buildings don’t do that – some shady shit is going on.” Does he find credence in some of the conspiracy theories about 9/11? “Absolutely! Are you kidding? I’ve read everything. I saw it. This shit doesn’t happen. It was controlled demolition.”

Basinski and his friends turned to the loops for solace. “No one on TV knew what the fuck was going on. The radio too, so we turned it all off, turned the music on and just sat up there and looked at that smoke, in shock.” He videoed the burning site as night fell, and used stills from the film on the covers of the four albums he released, collectively entitled The Disintegration Loops, in 2002 and 2003. Those frail, hopelessly mortal melodies, clinging on with dignified tenacity, became powerful allegorical elegies for both the horror and the enduring humanity of 9/11. The loops were performed by an orchestra at New York’s Metropolitan Museum of Art to mark the 10th anniversary of the attack, and the recordings feature in the 9/11 Memorial & Museum.

The pieces made Basinski’s career, and he has since released numerous other albums, including this year’s On Time Out of Time, featuring time-stretched recordings of gravitational waves picked up from deep space. It’s typical Basinski: minimal, glacial, but emotional, borne out of a commission he’d had to soundtrack an art installation about black holes. His life is still somewhat precarious – last year he pleaded with fans to buy his albums so he could pay his utility bills – but he says there are “little income streams”, and he’s managed to buy a small house in Los Angeles.

Workers adjust beams of the Tribute in Lights ahead of the 10th anniversary of 9/11. Photograph: Justin Sullivan/Getty Images

“It’s great there. New York is ruined. It’s a big Russian mob money laundering pit, just like all the other big cities in the world, and you can’t afford to live there unless you have a trust fund. And there’s plenty of international kids with trust funds, living there, doing jobs they don’t need to get paid for, and looking like they’re homeless.” He makes an “aren’t I awful” face. “I’m being so mean!”

He nevertheless pokes his acid tongue at a series of US politicians: Ronald and Nancy Reagan, George Bush Jr and Trump (“that jackass”). Thanks to them, he says, the world has eventually become a “horrible bad soap opera that’s so tacky you can’t stop watching”. The Disintegration Loops feels like not just an elegy for 9/11, but a portent for our whole politically fractious, environmentally precarious era. “We’re still going through The Disintegration Loops,” Basinski agrees. “The whole world is falling apart. I can’t fight all this crazy-ass shit that’s going on in the world by marching in the streets. But I can create a different resonant frequency, taking people out of time for a minute.” If things fall apart, you can at least slow them down.

• On Time Out of Time is out now on Temporary Residence.