In Christopher Nolan’s ‘Interstellar,’ David Gyasi (who had his breakout role in 2012’s ‘Cloud Atlas’) plays Romilly, a NASA scientist onboard an intergalactic mission to find a suitable replacement planet for a dying Earth.

At one point during this mission, some members of the crew visit a planet in close proximity to a black hole, which disrupts time to the point that an hour on that planet equals seven Earth years – a time discrepancy that greatly affects Gyasi’s Romilly, who stays behind in orbit on the main spaceship.

Also part of this mission is TARS, a monolith-looking rectangular robot (voiced by Bill Irwin) that looks surprisingly real. As Gyasi explains, it looks real because, well, it is real and Irwin was in control of TARS' movements.

This interview is happening about 30 minutes late. I hope that’s not three and a half years in your time.

[Laughs] No, it felt like two and a half years.

You get to explain a lot of things, which helps laymen like me. Did you 100 percent know what you were talking about?

Well, it’s great for a layman like me to have to explain it, because it means that I have to go and least figure out what this means. I developed a very basic understanding of what it was that I had to say and, when I needed to be more technical, then I would seek the help and advice of Christopher Nolan. And he would fill in those gaps.

How versed was Nolan on set? Would he know the answer or did he have to look things up?

He would come with page, chapter, and verse of why this line was written like this or why this movement was made like this. He so detailed. It’s incredible, because I just realized that I could absolutely trust this guy, you know?

Nolan likes playing with time, he also did that in ‘Inception’...

And ‘Memento.’

But this one involves a black hole, which is an interesting phenomenon. How much time on set was spent talking about this?

Actors sort of hanging around on set waiting to go on or back in trailers or whatever, the conversation is a little bit about sports and a lot about current affairs. But, with this, it’s often about, “Oh, explain that to me again?” And that’s joyous, right?

Cooper [Matthew McConaughey] and Brand [Anne Hathaway] spend a couple of hours on a planet, while over 20 years pass for your character. Did you create a narrative of what he was doing all of that time? Were there board games on the ship?

Um, I didn’t focus too much on the board games. I think what it is Romilly is passionate about is what he would have looked into, but I think he would have run out.

Is there a TV?

Well, he had a few periods of sleep. And I think there’s a lot of thinking time. There’s a lot of dwelling time. And he’s possibly gone to insanity and back again and all of that is hopefully conveyed when they arrive back.

In my mind, I’m going to pretend that if he wasn’t completely caught up on, say, ‘The Wire’ or ‘Breaking Bad,’ he is now.

Yeah, yeah, yeah. Actually, that’s quite attractive, to get caught up on all of those. That would be cool.

When you’re filming a scene, what did TARS look like to the actors? He looked real.

TARS was there. And Bill Irwin, who plays TARS, was there with us. He would control him; he would do the voice. And that is beautiful, the relationship that they have – the comedy duo. TARS was absolutely there, it happened live. That’s not a spoiler, is it?

And Bill Irwin is best known, maybe, as the guy who is not Robin Williams or Bobby McFerrin in the ‘Don’t Worry, Be Happy’ video.

And he is a gentleman of huge proportions. I loved working with him.

So that metal TARS was just there? That’s great.

As you see TARS was how he was there. They made him a fully functional moving – there’s very little CGI on him.

Mike Ryan has written for The Huffington Post, Wired, Vanity Fair and GQ. He is the senior editor of ScreenCrush. You can contact him directly on Twitter.