If you’ve heard about Solvej Balle’s On the Calculation of Volume I, longlisted for this year’s International Booker prize, you may have experienced a sensation that is central to the Danish writer’s brand of philosophical speculative fiction: deja vu.

In Balle’s five-book opus (of a planned septology), the first three of which won the prestigious Nordic Council literature prize in 2022, someone wakes up to find they are reliving the same day over and over. Their partner, family, neighbours: they all experience this day for the first time in their life. Only the protagonist has been there before. That person is a woman called Tara rather than a man called Phil, and the day is 18 November rather than 2 February, but the plot resemblance to Groundhog Day is striking.

The only thing is: Balle got there first. When Bill Murray, Andie MacDowell and the groundhog Punxsutawney Phil hit the big screen in 1993, the kernel of Balle’s story had already been stewing in her brain for six years. An obsession in her 20s with James Joyce’s Ulysses – set entirely on 16 June 1904 – had led her to wonder how much a single day could contain: “The thing that fascinated me most was the question: how can one day be so voluminous?”

She decided on the title in 1989, though she didn’t start writing for another 10 years and the first volume wasn’t published in Danish for another 20. Watching someone turn her idea into a box-office hit in the meantime was a relief rather than a blow: “I thought, ‘Oh, that’s nice, somebody’s helped me to do some research and gone in a direction I wasn’t going to go anyway.’” Because even when Bill Murray tries to kill himself in increasingly gruesome ways, he keeps on waking the next day. “That’s a very clear body-soul split; his soul just continues all the way through.”

In On the Calculation of Volume, the balance of mind and matter is a more cryptic affair: Tara Selter, a rare-book seller in her late 20s living in rural France, may be caught in a time loop, but she’s still tied to the material world. Her hair grows, her body ages, a burn on her skin slowly heals. Food she eats is missing from the fridge the next day. There’s a rare Roman coin that vanishes and then reappears, a coffee grinder that has to be bought several times before it stays. The parallel universe that Tara has fallen into has “a different philosophy of things”, and the hypnotic appeal of Balle’s fiction lies in the fact that her protagonist is not merely a hero seeking to escape a predicament, but an inquiring scientific mind earnestly trying to unravel its fixed laws.

Balle herself has moved through life in non-linear ways. Born in 1962 in South Jutland, she has “done all the things you shouldn’t do if you wanted a career”. During her high-school years, she zigzagged between Denmark and Paris, where she first worked as an au pair and then caught the writing bug, hanging out at legendary bookshop Shakespeare and Company. She studied literature for a while and then took a degree in philosophy but didn’t finish it until she was 56.

Her debut novel Lyrefugl (Lyrebird) was published when she was 22, but it was her 1993 book According to the Law: Four Accounts of Mankind that truly made a mark. A quartet of interlinked philosophical parables that was translated into multiple languages, it turned the heads of literary Copenhagen. “I remember thinking, this is world literature,” recalls Jes Stein Pedersen, literary editor of Danish broadsheet Politiken. “It was a truly original voice.”

But, in May 2005, Balle swapped the Danish capital for Ærø, a small island with a population of just under 6,000 people in what Danes call the “rotten banana”, the peripheral belt of marshland and islands in the southern part of Denmark. “I was kind of unhappy with the Danish publishing world, which became more and more commercial, more and more about bestsellers and all that shit.”

But she laughs at the idea that she became a recluse and stopped writing, as some critics have claimed. “Denmark’s cultural scene is as centralised as England’s: if you move out of Copenhagen, it’s almost like dying,” she laughs. “This idea that I am about to make my comeback is nonsense – I was there all the time.” After publishing a book of art criticism and a political memoir, Balle set up her own publishing house, Pelagraf, in 2011, bringing out two books of short minimalist fiction, If and Then, and the first five parts of her septology.

She is dismissive of the suggestion that life on a small island may feel much like the repetitive time loops that her character experiences. “Here, at least, there’s the summer where you’re doing certain things and then there’s a winter – in the city people do the same things all the time,” she says. “Nowadays, cities are so much more conventional than the countryside, whereas it used to be the opposite.”

She did find it easier to focus on the ever-expanding universe of Tara’s 18 November away from the city, she concedes. “I had to have more space in order to be able to keep all the bits in my head at the same time,” she says. She used to sing in the local choir but had to stop because she couldn’t hear so many voices concurrently. “I can sometimes go for days without seeing anyone.”

At the beginning of the first volume, Tara is romantically and professionally intertwined with her husband, Thomas, who is also a rare-book dealer, with her scoping out new acquisitions and him managing the sales from home. Tara tells her partner about her predicament, and even amid their confusion they are happy: she likens their relationship to a “quiet weather system with no natural disasters”. Is On the Calculation of Volume a love story?

“When I started out, I had the feeling that I was writing a love story,” Balle says. “But was it only a love story? I don’t think so.” If her books are an investigation into what is truly essential to the human condition once our routines are hollowed out by repetition, then book one concludes that love isn’t it. By the end, Tara has left Thomas behind in the countryside.

What Tara truly cannot do without, it turns out, is not the weather system of her matrimonial love, but the actual weather. In book two she travels to southern and northern Europe to recreate the seasonal change that the time loop has taken from her. She becomes increasingly concerned about her consumption of resources and her inability to regrow them. What set out as a love story turns into a parable about humanity’s abusive relationship with the natural world.

Can the time loop be broken; can Tara escape her fate? In part three, which Faber will publish in English in November, translated as the others have been by Barbara J Haveland, Balle’s protagonist encounters other loopers, and there are some shoots of hope. But, by the sound of it, the author herself hasn’t found all the answers to the mysteries of the world that have grown inside her head for nigh on four decades. She’s currently plugging away at volume six, and wrestling with quantum physics and Epicurus. “I like the idea that you’re allowed to keep your brain while going into a book,” she says. “I don’t know why we’ve got brains if they can’t be part of literature.”