Apparently Eddie Redmayne likes to play in deep water. His performance as Marius in Les Miserables alongside Anne Hathaway and Hugh Jackman got him some serious respect. But now he’s stepping into the shoes of one of the smartest men in the world, Stephen Hawking.

Most of the world nowadays only knows Stephen Hawking as a man in a wheelchair who talks through a computerized voice synthesizer, yet is still one of the most brilliant minds alive. Redmayne’s challenge in the new film The Theory of Everything is to embody a young, walking, talking Stephen Hawking, a role that will define Hawking’s younger years for millions of viewers.

Redmayne wanted to make sure he got it right, so he went to see the man.

“I met Stephen maybe four or five days before we started filming, which was an amazing experience. I’d spent four or five months preparing and so by this point — he has iconic status anyway — but by this point he was a complete idol of mine. So I was incredibly nervous when I met him. We got to spend a few hours with Stephen and some of his carers.”

One of the things that struck Redmayne about Hawking is his sense of humor. Anyone who has ever tried to communicate humor via text message can only start to relate what it must be like for Hawking.

“It’s difficult for him to speak because he uses this muscle here in his eye to communicate. And so it takes a long time for him to speak, or to say sentences.

“He has an extraordinary sense of humor. Also, because he takes so long to write things now he has this extraordinary capacity for one-liners that knock everything else out of the park. And his timing is extraordinary.”

Redmayne relates how he was nervous talking to Hawking, and how Hawking used one of his nervous spurts to make a joke at his expense.

“I was so nervous meeting him, that I just literally was just talking complete and utter gibberish at him, about him, and eventually I was just running out of things to say. And in a desperate attempt to fill the silence, I was saying how he was born on Gallileo’s birthday, on the eighth of January, and I was born on the sixth of January. I was saying, ‘We’re both Capricorns,’ and as I said it, I was like, ‘Why did I just say that?’. He started typing away, and about six minutes later, he said, ‘I’m an astronomer, not an astrologer.’ And I don’t think I’ve ever felt so small in my life.”

So far, Redmayne’s performance is already heating up use of the “O” word: Oscar.