Ballet Rambert is the epitome of modern dance, always innovative, always thoughtprovoking, always exciting and always visually stunning. And yet

it has never lost sight of its classical roots in Marie Rambert's Russian dancing school.

At the Theatre Royal this week the company, now celebrating its 80th year, give us four dances, including its current Olivier-award nominated piece, Constant Speed.

This is a tie-in with the Institute Of Physics to mark Einstein Year, and is a new work by Mark Baldwin which uses the dancers as molecules in space, being jostled by unseen forces.

Performed to the sparkling waltzes of Franz Lehar this is an energetic, colourful and vibrant piece of modern dance, visually surprising and physically demanding.

The programme opens with Pond Way, a new piece choreographed by the legendary Merce Cunningham, father of modern dance.

This is Cunningham's eighth piece for Rambert, danced against a backdrop of a dot landscape by the late Roy Lichtenstein.

On to the stage come 13 dancers in tracksuit trousers and floaty tops, moving sometimes in slow motion, sometimes frantically, and coming within millimetres of each other. It is an abstract image of insects scuttling through a pond, stones being skimmed across water and sometimes the struggle for survival at the bottom of the pond.

In Judgement Of Paris, first seen in 1940, three ageing prostitutes in a sleazy bar try to seduce their only customer. This dance is to extracts from Kurt Weill's music for the Threepenny Opera and is told with humour, capturing the cabaret style of Thirties Berlin that could serve to describe any fin de siecle society.

Divine Influence is a duet based on the tough exercises designed for the perfection of ballet technique. Martin Joyce's choreography for himself and fellow dancer Angela Towler is performed to the third movement of Beethoven's Moonlight Sonata.

It is not always beautiful but the dancing is muscular and physical. But don't worry if you know nothing about Einstein, Kurt Weill or indeed anything about modern dance. Just sit back and watch human movement at its most complex and best.