Actor Eddie Redmayne talks about taking on the formidable role of playing Stephen Hawking in "The Theory of Everything." Upon first meeting Hawking, the actor was overwhelmed in the presence of his genius. Luckily, it got better from there. . .

Is there a more daunting task than portraying one of the most brilliant minds of our time? Ask Eddie Redmayne, who embodies the renowned British astrophysicist Stephen Hawking in the movie The Theory of Everything, and he’ll tell you the stakes are terrifyingly high. In fact, the talented actor, who previously charmed audiences as Marius in the movie adaptation of Les Miserables, says accepting the role of Hawking, which he chased after "hardcore," was both euphoric and like a fear-inducing punch in the stomach.

In The Theory of Everything, Redmayne transforms himself not only into the Stephen Hawking we all know, but gives us a glimpse into a lesser-known chapter of the famous scientist's life when he was young, healthy and a student at Cambridge University. He meets fellow student Jane Wilde and their romance becomes a love story of historic proportions: at age 21, Stephen is diagnosed with the motor neuron disease amyotrophic lateral sclerosis (ALS), and through the power of love he and Jane beat the odds together, making it possible for Hawking to break new ground in science.

Stephen Hawking Photo

Eddie Redmayne as Stephen Hawking (right) and Felicity Jones as his wife Jane in the biopic "The Theory of Everything."

With Oscar buzz already swirling around Redmayne, we caught up with him at a roundtable interview during the movie’s world premiere in Toronto. Here's what he had to say:

So how intimidating was it to play Stephen Hawking? 

Well, I spent six months researching him, reading everything, finding as much photographic footage as I could, and then I got to meet him five days before filming. I suffer from verbal diarrhea so I basically vomited forth information about him to him. (Laughs.) But once I got over that stage he was incredibly generous.

Did Stephen have any advice for you about how to play him?

One of the first things he asked was: 'Are you playing me before the voice machine?' I said, 'Yes,' and he told me his voice was very slurred. So over six months I met maybe 40 or 50 people who suffered from motor neuron disease and I asked them how it affects your tongue muscle and prevents you from being able to speak. And I went back to the writer and the producers and told them Stephen has said we really need to push this to the reality of what it was. There is riveting documentary material where only his students and Jane would understand what he was saying. We never really got quite as incomprehensible as he did before he had the tracheostomy, but we got close enough given that it was one of the things he spoke to me about.

How did you land the role?

I chased it down quite hardcore. I had seen [the director] James Marsh’s [documentary] Man on Wire, which is one of my favorite films, and I managed to bulldoze my way onto a phone call with him. He asked me how I would play this role, and I made up stuff, just trying to sound confident. (Laughs.) He wanted to know specifically about the physical side of how I would play Stephen so I sent him a very little seen film I did with Kristen Stewart called The Yellow Handkerchief, in which it was a more physical character that I had played. We went for a drink, he offered me the part, and I had this extraordinary moment of euphoria that lasted for about a second and half and then it was like a punch in the stomach of fear and it’s been like that ever since.

How did you transform yourself?

When I got the part I tried to go about it in a kind of old school Hollywood way surrounding myself with a team. I got the most extraordinary makeup designer, a phenomenal costume designer, a voice coach and a choreographer named Alex Reynolds. She and I spent months going to motor neuron clinics. There is no documentary material when Stephen was healthy so we showed old photos of him to specialists who could see what became withered and spasticated. Because even though the muscles stop working, actually how they end up not working is really contorted – they’re spasticized – so it wasn’t just about me sitting there and doing nothing, it was about me finding muscles that I’d never used before. Alex helped me find that in my body so it was a lot of time for me in front of a mirror. 

Theory of Everything Photo

Redmayne visited motor neuron clinics to research the physical effects of Stephen Hawking's disease, and then worked with a choreographer to portray his physical deterioration. (Photo: Liam Daniel/Focus Features)

The movie is based on Jane Hawking's memoir Travelling to Infinity: My Life with StephenWho do you think Stephen would be without Jane in his life?

Jane is an extraordinary human being. She’s incredibly intelligent. She has a backbone of steel and yet has this wonderful warmth and fragility. Felicity [Jones] was so extraordinary in this film because it would have been so easy to go for the big drama because people don’t know Jane as much as they know Stephen. But Felicity kept absolutely true in her subtlety and her microscopic detail of Jane. Jane is a formidable human being and I think Stephen would absolutely say he wouldn’t be anywhere near where he is without her support.

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Felicity Jones plays Jane Hawking opposite Redmayne's Stephen. The actors say that Jane was very generous in sharing her world and invited Jones to look at everything from the dresses she wore from that time period to old family photos. (Photo: Liam Daniel/Focus Features)

The ALS Ice Bucket Challenge during the summer drew a lot of attention to the disease. What did you learn about ALS from playing Stephen and what did you think of the challenge?

I went to this clinic in London with a doctor and met so many people and families who are suffering as a consequence of this disease. Someone described it to me as if you’re in a prison and the prison walls are getting smaller every day. They’re no closer to finding a cure in almost a 100 years if not more. The idea of raising awareness about it and donations going toward it is the greatest thing in the world especially if you know people with this condition. It’s all progress and it’s wonderful.

Do you approach playing a real person differently than a fictional character? And is there another real person you would want to play?

I think you probably approach it in the same way, but the regimen you have to go through particularly if someone is living or iconic can be more intense because you are going to be judged by the way they look, the people that know them, and that forces you to stick to the absolute truth or as close as you can get to it. If you're playing people that are less well known or who have died, you can actually make more artistic choices. The next film I’m doing is a true story called The Danish Girl, and I’m playing Lili Elbe who was born Einar Wegener – she was one of the first transgender operations. She’s no longer alive, but there is a lot written and again it’s lovely to source those things again and find as much material as I can about her. 

Stephen Hawking Photo

The real Stephen Hawking changed the way we look at the universe. Here he is pictured during a speech he delivered to mark NASA’s 50th anniversary in 2008. (Photo: Paul E. Alers/NASA via Getty Images)

Do you know everything about the universe now?

Yeah – don’t you? (Laughs.) Absolutely not. The biggest acting challenge was trying to pretend that I understood all of those books I read. I did keep arduously going through them, but I didn’t want anyone to ask me about them. (Laughs.) My biggest fear was doing press for the film and someone asking me to explain.

And what was Stephen’s response after he saw your performance?

It was scary. I got to see him just before he went into the screening, and I said, 'Stephen, I’m very nervous. Let me know what you think.' And he spent a few minutes typing something out and he said, 'I’ll let you know what I think, good or otherwise.' I was like, 'Stephen, if it’s otherwise will you just say 'otherwise?'' (Laughs.) When we had made the film, we used a synthesized version of his voice, our approximation of it, and after seeing the film, Stephen gave us the copyright to use his voice. So it is his voice that you hear in the film. For me, that was the most wonderful validation.