JENNIFER LAWRENCE: I watched The Theory of Everything with my jaw dropped the entire time. You were so fantastic! I didn’t even know some of that was possible.

EDDIE REDMAYNE: Well, thank you. When I was cast, my mate Charlie Cox, who plays Jonathan in the film, said, “If you get the opportunity to play Stephen Hawking, you have no option but to give it your everything. You have to give 8,000 percent.”

LAWRENCE: Did that scare you?

REDMAYNE: Oh, it was petrifying!

LAWRENCE: That would scare the shit out of me.

REDMAYNE: You do that thing of trying to chase down the job, sounding incredibly confident because you never think you’ll get it. And then you get offered the job, and you have a moment of euphoria, and then you basically want to be sick for the first year.

LAWRENCE: I don’t know if you get this, but I get embarrassed really easily when I have to have big meltdown scenes. Do you get self-conscious?

REDMAYNE: Are you kidding me? I’m just one gigantic ball of rancid fear and self-consciousness. I’m entirely fueled by fear, so the fact that I knew it could be a catastrophic disaster made me unable to sleep, and made me work quite hard.

LAWRENCE: It looked like you lost a lot of weight.

REDMAYNE: I lost, like, 15 pounds at the beginning of the film. With the disease, Stephen did lose a lot of weight. But we couldn’t shoot chronologically, so we were having to jump between different time periods within the same day. Our extraordinary makeup artist, Jan [Sewell], and costume designer, Steven [Noble], did clever things like making the collars tight and my makeup look healthy in the morning, and then, if in the afternoon I was playing him older, they would mess with proportions—the collars would become bigger or they would use slightly oversized wheelchairs. But it was a real work in progress. Do you ever watch dailies?

LAWRENCE: No. Unless I keep getting the same note and I’m obviously not getting it, then I’ll watch it again on the monitor. But, oh my God, did you watch rushes of this?

REDMAYNE: We sort of had to, because we were jumping in and out of all these different time periods and trying to track the illness and the physical decline. I had an iPad with all the documentary footage of Stephen and then we had the dailies. I kept hoping that the two things were going to meet, but obviously they never did. [laughs]

LAWRENCE: Maybe watching dailies would make me better. Every time I’m at a premiere, all I’m doing is thinking, “Oh, you shouldn’t have said it like that!” Actually, it would probably just make me neurotic. What was your most helpful tool? Was it the Stephen documentaries?

REDMAYNE: Good question.