In his New York East Village studios, Glass smilingly admits that one of the reasons he chose to work with Zimmerman is: “‘Accessibility’ isn’t a bad word for her. Many people I’ve worked with – such as Robert Wilson or JoAnne Akalaitis [his first wife] – were very experimental, and there was a much tougher, hard-edged line to those productions.”Fans and detractors alike would agree that “accessibility” is a quality that has rarely graced Glass’s enthralling but infuriating collaborations. Einstein on the Beach, the first, longest, most famous and possibly most difficult of his 18 operas, explored the beginnings of atomic energy and tested audiences by exploding the operatic form into a four-and-a-half-hour work, whose then-unique Eastern-influenced notions of rhythm blended with the avant-garde director Robert Wilson’s arrestingly symbolic visual style. Galileo Galilei is far slighter, at one and a half hours, and has a distinct narrative, unlike Einstein’s image-fuelled progress. Indeed, Zimmerman, whose trademark is to improvise a script through rehearsals, relates that Glass wouldn’t write a note before she produced the whole, carefully structured libretto.The director explains that both she and Glass decided that scientific imagery rather than the political aspects of Galileo’s life was going to dominate their work. “I think that Galileo has mistakenly been made an icon of rationality because of his conflict with the church,” she declares.

“But I wanted to capture the great passion in his science – the fact that his groundbreaking theories were simultaneously influenced by an enchantment about the world. That was all connected to his religion.”As a director, Zimmerman can certainly do passion. New York is still buzzing with delighted reactions to her spellbinding production of the Metamorphoses, which is staged round a swimming-pool built in the middle of a theatre. Imagine a tear-stained girl on one side of that pool, begging her lover not to break their idyll of happiness by going on an ocean voyage. He tells her not to worry and strides out into the water, which suddenly takes on the bilious green of a stormy sea, chopping and churning uncontrollably until eventually he is dragged below the waves. His dying wish is for his body to be floated back to his lover, who waits for him on the shore: when she sees him, her grief is so transcendent that they are both transformed into halcyon birds – a process depicted by the two actors slowly rising up and flapping their arms with a dancer-like grace as they leave the pool.That portrayal of the story of Alcyone and Ceyx gives an important clue to how Zimmerman approached a problem only partially answered by plays such as Michael Frayn’s Copenhagen and David Auburn’s Proof.

That problem: what can make the dry seeds of scientific or mathematical theory bloom into life in the theatre? Her answer is to focus on scientists whose conceptual breakthroughs are imbued with an almost mythic wonder. She concedes that her subject matter – rather like the subject of Leonardo – lends itself more easily to picturesque dramatisation than to, say, the forehead-expanding equations of particle physics, and tells how her collaboration with Glass kicked off with one striking image.”Philip was transfixed by the idea of Galileo becoming blind, and he had a picture in his head of this blind man sitting next to a telescope. This individual who transformed our way of seeing talks about his loss of sight in his letters as if it were a judgement upon him at the end of his life.”Zimmerman and Glass wanted the opera to build to an optimistic climax, so they have retold Galileo’s life in reverse order, starting with Galileo questioning himself and God about the repercussions of his defence of the theory that the Earth orbits the Sun It ends with an opera within an opera. “I found out from our conductor that Galileo’s father, Vincenzo Galilei, was a famous composer, apocryphally credited with having invented the opera,” Zimmerman says. “So I felt we should go back to a point where Galileo is seen as a little boy, watching an opera by his father about the Sun, Moon and stars.”Glass’s score for Galileo Galilei is possibly his most melodic. “We’ve gone through 50 solid years of difficult music,” he explains, “and I didn’t want to make the music an obstacle. The issue here is not being on the cutting edge – I think that the beauty of the singing and the simple materials that we use provoke enough interest of their own.”I ask Glass if the far-reaching influence of his music makes him feel any affinity with Galileo as a man who transformed his age through his ideas, and he replies, “Some people think so, but I’ve never made that claim, and you rightfully would be suspicious if I did.

One rather nasty critic said: you know that Philip Glass, he’s not a very good composer, but he’s good at working with people more talented than himself.”‘Galileo Galilei’, Barbican Theatre, London EC2 (020-7638 8891) 1–9 Nov. While Louis Lortie must have drawn a lot of the potential audience to the Queen Elizabeth Hall the same evening, the young Australian pianist Alexander Boyd still managed to pack in a crowd at the Wigmore Hall. Perhaps they were fellow students – they were certainly enthusiastic – for Boyd has done much of his training in London. Odd word, “training”, though the life of a performer must be a test of many qualities besides the artistic. Boyd certainly seemed well trained, but his artistic potential remained in doubt. Perhaps it was too simple, though he allowed the slow middle movement to breathe in a relaxed and natural way.More was needed, though, in the eight short pieces of Schumann’s Fantasiest?, Op 12. He merely traced the surface of this deeply poetic music, oblivious to its atmosphere of enchantment, impervious to its intimately personal appeal.