The Life of Galileo, NT Olivier, London</br>Eh Joe, Duke of York's, London</br>Performances, Wilton's Music Hall, London

'Now suddenly we are moving," exclaims Simon Russell Beale, kicking off David Hare's version of Brecht's The Life Of Galileo and thrillingly embodying the great Renaissance scientist who helped spark an astronomical revolution. In Howard Davies' new production, a vast crescent moon is seen through a skeletal domed roof, magnified as if viewed through a telescope, while Galileo starts dangerously proving Copernicus' heresies were right and the papal doctrine about Earth being the fixed centre of God's universe is claptrap. At the close - when he has been intimidated by the Inquisition and publicly recanted, while his ideas are, nonetheless, still being spread abroad - we catch a final glimpse of our world, out in space, beginning to spin.

What comes across strongly, though not too didactically, is the link between Galileo's progressive science and subsequent massive sociopolitical changes, with heated discussions about the Church's authority and the undermining of the old hierarchical order.

Ultimately this is Brecht's most engagingly human and gripping play and Hare's compact version, performed naturalistically, combines big ideas and ethical complexities with an urgent sense of momentum.

There are a few glitches, not least an obtrusive, satirically dull cabaret number with dancing tarts in dog collars. Given that few Italian academics worry about being burned at the stake these days, some might also be irked by the modern costumes. But these create a dramatic immediacy and underline the persistent relevance of this portrait of frightening religious fundamentalists and of supposedly decent rulers sanctioning torture.

Oliver Ford Davies is a subtly disturbing Cardinal Inquisitor, almost twinkly and chortling before clenching his jaw. And Russell Beale - probably the best actor on the planet when it comes to embodying sorely tried intellectuals - is on brilliant form: razor-sharp, droll, inspiring and full of earthy vigour too.

Brecht works have certainly been revitalized in recent years, after the worst days of the Berliner Ensemble posthumously turning them into rigid museum pieces. Perhaps Sam Beckett's literary estate is loosening up too, after notoriously insisting everyone revere his precise production instructions. Eh Joe is his TV play from 1965 translated to the stage by Atom Egoyan. Michael Gambon, a silent star in the title role, shuffles around a shadowy brown bedroom closing curtains over every window and door. Then he slumps on his bed, seemingly relieved for a moment, only to be plagued by the disembodied voice of a woman (Penelope Wilton) who harps on his decrepit isolation and past cruelties. She is like his nagging conscience, like some tormenting invention of his schizophrenic brain or an uninvited character muttering inside a playwright's head.

Though lasting barely half an hour, Eh Joe is a small, strangely mesmerizing forgotten gem. Wilton's exquisitely paced delivery contrives to be soothingly mellifluous, melancholy and barbed. The original TV camera work created more tension, inching nearer and nearer to Joe's face. But eeriness and intimacy is generated with live video projection as we snoop on Gambon through a misty scrim and simultaneously see a huge close-up of his hangdog face floating before us. His rheumy eyes register tiny flickers of emotion, only once or twice darting melodramatically, more often ambiguously capturing terror, tearful self-pity, repentence and maybe some deep, growing sense of sympathy.

Beckett's estate once famously threatened to terminate a Godot production which involved music, an element which proves integral to his compatriot Brian Friel's Performances. Featuring Henry Goodman as Leos Janácek and the Brodsky Quartet live on stage, this chamber play-cum-concert mulls over the relationship between the composer's private life and his professional output when, aged 74, he was writing passionate missives to Kamila Stösslová (a married twentysomething) and composing his vibrant String Quartet No. 2, entitled Intimate Letters. Performances is a haunted biodrama or what one might call a "muse play". Goodman's Janácek, bustling round his old music room in Brno, is a ghost or figment of his modern-day admirers' imaginations. He engages in jovial chats with the Quartet as they prepare to practise and has a long, argumentative conversation with an academic, Rosamund Pike's Anezka, who starts out romantically entranced by his love letters to Kamila.

Friel raises some sharp questions about analysing artists' works and about biographers' motivations. Implicitly voicing Anezka's own doubts, Janácek insists his richly complex music transcends his billets doux which he now (rightly or wrongly?) dismisses. Maybe there's a hint of autobiographical identification too, Friel's play having premiered in his own 74th year. Regrettably however, he is not at the height of his powers here. Though experimentally interweaving actors and musicians, the result feels theatrically stiff. Goodman is an admirable pianist and lively Janacek but he is allowed by director Lou Stein to slip into his saccharine mode and the Brodsky Quartet simply aren't good actors. Their climactic rendition of Intimate Letters is electrifying but you can't help wishing they'd just played the music and ditched the play.

k.bassett@independent.co.uk

'The Life Of Galileo' (020 7452 3000) to 9 August; 'Eh Joe' (0870 060 6623) to 15 July; 'Performances' (020 7702 2789) to 15 July

'The Independent' has reserved 200 tickets to see 'The Life of Galileo' on Wednesday 16 August followed by a drinks reception attended by members of the cast. Tickets are £10. To book, call the National Theatre Box Office on 020 7452 3000 and quote 'Independent'.