Eddie Redmayne on stepping into the shoes of a genius in The Theory of Everything

In his first lead film role, Eddie Redmayne takes on the daunting task of portraying the extraordinary life of the physicist Stephen Hawking.

Eddie Redmayne at the 2014 Toronto International Film Festival in Toronto. Chris Pizzello / Invision / AP Photo

Time is relative, especially for young actors tasked with playing brilliant theoretical physicists.

Eddie Redmayne estimates that the euphoria of being cast as Stephen Hawking in The Theory of Everything lasted a millisecond. Then came the overwhelming fear.

“And that fear remained the whole way through the process,” Redmayne says.

The 32-year-old Briton was asked not just to lead a film for the first time, but to play a mathematical genius across decades of physical degeneration – all under the watchful gaze of the said mathematical genius, who ominously told him: “I’ll tell you what I think, good or otherwise.”

When Hawking saw the film he judged it “broadly true”.

In the year’s most technically complex role, Redmayne gives what’s surely the performance of his young career (he won the Golden Globe for Best Actor in a Motion Picture, Drama this week), one that seeks to capture not only the deterioration that transformed Hawking from a healthy youth to a paralysed adult, but (more importantly) the scientist’s unvanquished spirit and the unimpeded expansion of his imagination.

“He was given a death sentence,” says Redmayne, referring to the diagnosis of motor neuron disease Hawking was given as a 21-year-old: he had only two years to live.

Now 72, he went on to father three children, marry twice and make significant discoveries in cosmology, publishing the best-selling A Brief History of Time on the way.

“So you live every single moment to the full and that’s what I wanted an audience to leave with. That’s what I left this experience with,” says Redmayne.

The director James Marsh (Man on Wire) remembers well his first meeting with the London native Redmayne. One pint turned to five, the conversation going on into the night.

“He was just full of ideas and passion for this,” says Marsh. “He knew somewhat what this might entail in terms of preparation and physicality. Eddie’s crazily ambitious – he’s not ambitious for money or fame. He’s ambitious to do great work. He’s fearless, too. It was a real leap into the dark for him.”

Redmayne plays each stage of Hawking’s increasing disability, going from a lame leg to a walking stick, to two sticks, to a wheelchair. Gradually he loses his voice, his body language, his facial expressions.

“It felt like solving a puzzle,” says Redmayne. He spent four months researching, working on the physicality and feebly studying Hawking’s physics. He trained with a choreographer, met academics (Redmayne also went to Cambridge), visited many ALS sufferers and had an expert study old photos of Hawking to trace the disease’s effects.

“There were moments along the way where I know he felt really, really defeated,” says Marsh.

To guide him, Redmayne had three photos in his trailer: Albert Einstein, James Dean (since Hawking was, Redmayne says, “a ladies’ man”), and a joker playing card, to capture Hawking’s playful side.

“If you’re in a room with him, he’s definitely running the room,” says Redmayne.

Aside from all the technical challenges, Redmayne imbues Hawking with a sly mischievousness. Much of the performance is in a glint in his eyes.

“What emanates from him when you meet him is this kind of wit and humour,” says Redmayne. “Even though he can move so few muscles, he has one of the most charismatic, expressive faces you’ve ever seen, which is a weird irony. There were many things I found out from meeting him, but one of the overall things I took away was finding he does not live a disease. He lives forward and has done since he was 21 years old. There’s an unerring optimism to him.”