Time spent at the Centre of Time at the University of Sydney helped writer Bryan Walpert get his head around the logistics of time travel for his new novel Entanglement. Bryan is a Professor in Creative Writing at Massey University, Auckland, with a novella, a short story collection, four books of poetry and two of literary criticism to his name. Entanglement though is rather different. For a start it has three different time strands. There's a time traveller who's landed in the 1970s from the future, in a desperate bid to save his twin brother's life. But his memory is impaired, and he has few clues to work with. There's a novelist who's firmly in 2011 in Sydney, who finds love while researching at the Centre of Time. And in 2019, an obsessive writer is trying, and failing, to come to terms with his marriage ending. Lynn Freeman talks with Bryan Walpert about the joys and pitfalls in writing about time travel.