DAVID GREENE, HOST:
We're going to spend some time now with a man named John Urschel. He's an NFL football player, a big offensive lineman for the Baltimore Ravens. His other passion is crunching numbers. He's a mathematician, a widely published one. Urschel does take comfort knowing that an inspiring career awaits him after football. And he was listening closely when a fellow NFL player, the San Francisco 49ers' Chris Borland, announced his retirement recently after just one year playing.
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CHRIS BORLAND: To me, the decision was simple after I'd done a lot of research. And it was personal. I was concerned about neurological diseases down the road if I continued to play football.
GREENE: That was Borland speaking to CBS. And his decision was the backdrop when we spoke with John Urschel about football and also math. We began by asking him how he would translate his latest math paper for, say, kindergarteners.
JOHN URSCHEL: I came up with a numerical technique to try to approximately solve some quantity. And this quantity is called the Fiedler vector. And what this quantity is used for - it's commonly used in things such as graph partitioning or graph drawing. And by graph, I'm not talking about X-Y coordinates and the Cartesian plane. I'm talking about the set of discrete objects and the relationships between them.
GREENE: This is for kindergartners? Are you sure this is the kindergarten version you're giving me here?
URSCHEL: I'm telling you, this is about as kindergarten as it gets.
GREENE: (Laughter) OK.
URSCHEL: And I think the easiest example for people to understand is suppose you look at, say, Facebook.
GREENE: All right, now you've got me.
URSCHEL: So take all users of Facebook. And let's call them the discrete objects. And then the relationships between them is whether or not two people are friends on Facebook.
GREENE: This is complicated, what you deal with (laughter). Let's just - let's just leave it as this (laughter).
URSCHEL: Yes, yes. We can just call it complicated, and we'll leave it at that.
GREENE: I mean - and you are so passionate about it and so knowledgeable. I mean, I have to ask you which comes first, NFL football or math?
URSCHEL: Well, I'll tell you which one comes easier. Math comes much easier for me. It's something that I've been blessed with. It's something that's always come easy to me. And football took a lot of work for me to get good at.
GREENE: And that brings me to the deeper question I wanted to ask you. You're playing football. It's a sport that people have become more and more concerned about the health effects, you know, potentially long-term brain injury. For someone like yourself, you know, who has this other career choice, do you wonder if you're putting yourself at undue risk playing football?
URSCHEL: I am putting myself at risk. To say that I'm not is either me being ignorant or just outright lying to you. And I guess the best way that I could put my personal choices on the subject is this is a matter that I've really let my heart decide rather than my head. I love the game of football, and this is something I very much enjoy. And I want to continue playing professional football as long as humanly possible.
GREENE: Why?
URSCHEL: I love the game. I love the physical contact. I love the aggression. It speaks to a completely different side of me than what math speaks to.
GREENE: You know, you wrote about Chris Borland, who decided he's no longer going to play because of the risk of long-term brain injury. You said you're envious of him for making that decision. What do you mean by that?
URSCHEL: I'm envious of Chris Borland in that he's capable of saying that he has these great opportunities after football and that he had a great football career and that it's time to move on. That's not an option for me.
GREENE: That almost makes it sound like football is an addiction.
URSCHEL: It's very much an addiction for me. This is something that I really need in my life. This is something that if I don't have it, I'm not a very pleasant person to be around.
GREENE: I wonder, at a moment when parents hear so much about the dangers of football, you know, and they have kids who are thinking about, you know, dreams of football but also dreams of, you know, careers and other things, like academics - like math, maybe - do you worry about the message you're sending by, you know, sort of saying that football's an addiction? You just can't give it up.
URSCHEL: I think the message that I'm trying to send is that it's OK to do both. You can do both and be successful. But at the same time, I don't want kids and youth to look at me and say, I want to do what he did. I don't think being a professional football player is for everyone. It certainly isn't. And I think the best way I can explain that is when I have children - when I have a son, if he wants to play football, he can. And I'll let him. But that's not something I'm ever going to push on him or encourage him to do. And my life as a professional football player is not something I would want for my son.
GREENE: Why do you say that?
URSCHEL: Pro football's a tough game, man; believe me. It's a lot of contact. It's a lot of wear and tear on your body. You've got elite athletes running into each other, play after play, at high speeds. And this is something that I love and I enjoy. But for my child, this is something that I'd rather have him, say, being a math professor than doing that.
GREENE: John Urschel, great talking to you. Thank you very much for taking the time, and have a good offseason.
URSCHEL: Thank you.
GREENE: That was John Urschel, Baltimore Ravens offensive linemen and also a mathematician. This is NPR News. Transcript provided by NPR, Copyright NPR.