In 2005 Professor Ray Rivers, expert in Theoretical Physics at Imperial College London, presented Rambert's Artistic Director Mark Baldwin with a Bumble Ball.

A plastic kids toy with blunted spikes, the Bumble Ball, when switched on, will vibrate and jiggle around the room.

This, Professor Rivers explained, was a perfect demonstration of how molecules move in space. This, said Baldwin to his dancers, is exactly what I want you to do.

Hitherto disinterested in physics as "schoolboy stuff", Baldwin was commissioned by the Institute of Physics to choreograph a piece that would convey the magic and excitement of science to a wider audience.

And the result was Constant Speed, a fast, funny and colourful celebration of three of Einstein's most famous theories Special Relativity, Brownian Motion and the Photoelectric Effect.

"Brown was the first person to notice that, if you put a grain of pollen on water, it won't keep still," explains Baldwin.

"That's because it's being jostled about by the water molecules like if you tried to run across the pier in Brighton on a sunny day, you'd have to duck and dive because of all the people.

"Also, the colours in physics have very different energies," he continues.

"Red is a very weak colour. If you fire red at a sheet of gold, nothing will happen however much you increase the frequency, whereas blue light is strong.

"So we've got a couple of very powerful women in blue and lots of testosterone-fuelled men dressed in red."

With Rambert's dancers moving like hyperactive molecules to the sparkling waltzes of Frank Lehar ("it sounds like stars exploding, if you can imagine the gorgeousness of that"), Constant Speed has been nominated for a 2006 Olivier Award for Best Dance Production.

But it may not even be the highlight of Rambert's current programme, which also boasts the premiere of a work by enigmatic American choreographer Merce Cunningham, widely considered the father of modern dance.

Entitled Pond Life and inspired by Cunningham's favourite childhood game of skimming stones over a pond, it is lyrical, thoughtful and sensuous. Yet it is also one of his most advanced works and requires the efforts of 13 dancers.

"It's so technically edgy that the dancers really are having to use their entire bodies to achieve the effects," says Baldwin. "The torso is pulled and yanked in different directions and the legs are balletically active.

Because that's what Cunningham is his ballet teacher from the hips down and his contemporary teacher, Martha Graham, from the waist up."

Performed to the "calming hum" of Brian Eno, against a Roy Lichtenstein backdrop which looks like "water scraped across a wall", Pond Life is one of Cunningham's 'nature studies'.

"It really does give the impression of watching water flies skittling across the surface," says Baldwin. "The whole thing shifts and moves and then suddenly settles. It's beautiful, wonderful."

The programme also includes Divine Influence, an intimate duet performed to the third movement of Beethoven's Moonlight Sonata, and Judgment Of Paris, first performed in 1940, in which three prostitutes seduce a drunken client in a seedy nightclub, in time to extracts from Kurt Weill's The Threepenny Opera.

Starts at 7.45pm, plus Thurs mat 2pm, £11-£22.50, 08700 606650