Interview with the 2024 physics laureate John J. Hopfield, recorded on 6 December 2024 during Nobel Week in Stockholm, Sweden.

How big a role did physics play in your childhood? 

John J. Hopfield: I don’t know if you have children, but young children learn what their parents do. Parents do something highly visible, a fireman or something, and the children get tunnelled that way. I didn’t have a father who was a butcher or mother who would make bread. They were both physicists. So the only occupation I knew as a small child was the physicist. What else could you be? That’s what parents did. So I had a certain bias to begin with, and that was just left to explore the world with. 

My parents very much were content watching me explore the world with my hands and making things and making a mess and breaking things. We didn’t have television screens. After all, TV came to the United States when I was about 13, 14. I grew up without television, which is probably a great help. It meant that you were much more self-consistent, self-dependent for your own play. You couldn’t just sit there passively and look at the screen. Because I’m older, I have a very different childhood experience than most of the children you’ve ever seen. That had a great deal of influence on me. 

Is constant screen access hurting today’s kids? 

John J. Hopfield: What I see is, it’s so easy to lose doing, and becoming merely a spectator, setting a child in the corner. “Watch the picture! Find it funny. Don’t rely on yourself.” “Mama, daddy, change the film!” If you can even change the channel and nobody next to you doing it, it’s already exploration, which is more useful than sitting and watching. 

How do you stay curious as an adult? 

John J. Hopfield: How can you do anything, but let it run at any time you interact with the world? It’s your curiosity. I’ve never tired of learning new things, even at the cost of abandoning some of the things I’m doing at present in order to have mental space to learn the new ones. That’s a great adventure, but you have to decide whether you can take that or whether you’re looking for a monotony of some job. I think when 12-year-olds are exposed to what a certain line of job actually entails, I think they’ll spend a little more time trying to understand what the world has to offer for them. 

What advice would you give to a young researcher? 

John J. Hopfield: Don’t presume that you will be in the same field 10 years from now. It may be something which happens because you want it to, it may be something you don’t want. You want to go into this area discipline, and you find suddenly there are no jobs in it.  

Why is cross-disciplinary research important in science? 

John J. Hopfield: Really because most disciplinary lines are pretty arbitrary. You don’t want to get a place where you’re trying to pursue some interesting line and some particular peculiarity of this job structure, where the world says: “No, that’s for people who have background A. People who have background B have to do something different.” If you look at the number of people who actually change from something to something else in a major way, it’s not tiny. There’s no point in trying to say that the world is divided into these little chunks and they have different names, and you have to be in one of them. It just doesn’t help. In fact, it really hinders. Except it makes it easy at a low level to say, this is job A, this is job B, this is mathematics, this is geography. But after a while, you find out the geogenetic system is based on global satellites, and you want to understand what those are. Well, maybe you’d better know some mathematics. 

What are the greatest opportunities and risks presented by AI? 

John J. Hopfield: AI, even as we presently understand it, can be made into a marvelous augmentation of any doctor’s life. That kind of thing will occur in all kinds of fields. You’ve thought, “oh, it can’t do that. It can’t sympathise as well as I can.” And then it turns out people are happy interacting with a doctor who’s had some background in AI and everything becomes somewhat mixed. The difficulty is, of course, along with the good information, there’s lacking information. That goes into the mixture if you really don’t understand how AI works. 

I do wonder whether you can actually have available the most aggressive possible AI, which you also can’t control because you actually don’t understand quite how it works. AI is always, I think, going to be limited by the hazards it has. Just as nuclear energy is limited by the hazards that it has. But we’ve lived through quite a few hazards. The hazard in my lifetime, the nuclear energy hazards, the molecular biology revolution, which suddenly allowed all kinds of gene things to be done. Again, when that was first invented, there were many biologists who said, “Wait a minute. We have to stop research in that direction until we understand it”, because it had such potential hazards of doing horrible things at very low cost. You can ask whether the AI revolution is going to run into something where people say it really has to be chopped off, stopped, thought about for a while. 

I would say having life or death power to an agent whose actions you cannot predict is one of them. That question is going to come up very rapidly in medicine, for example, where the allocation of scarce resources depends on sensible use of who can actually benefit. When I say sensible use, does that mean sentient use or does it mean you can actually hand the job over to a computer, which says “This person gets the treatment, that one does not?” I think there’s a good deal of social unrest, which would also attend trying to move anywhere on that boundary. 

Reflecting on your career, do you have any life advice? 

John J. Hopfield: The astonishing thing for me is the idea of being here in Stockholm as a representative in some sense of physics. So unlikely, so absolutely unlikely.  

Stay healthy. Don’t ask too much, and independently do interesting things. It doesn’t matter what they are. Interesting is the important one. 

How did you convey your passion for learning to your three daughters? 

John J. Hopfield: Interesting question. None of them became scientists. They almost did and then didn’t. The trouble with coming from physics is being a lover of mathematics helps, and mathematics education for women just somehow is not as well pursued in the US as it could be or ought to be or what have you. It is easy to fall into the thing where instead of you going into astronomy, you go into economics. Little less math, little less science. That’s what one of them did. Another of them went into biology, and got as far as a PhD in biology and neuroscience in fact. Then looked around at the job market. And then the interesting jobs in biology are actually management jobs. So the middle daughter got a degree in management after getting a biology PhD and is now very successfully pursuing whatever mixture that’s called.  

But what she actually got out of her upbringing was the idea that you were responsible for it. If you’re getting toys, I would say simple toys, that have things that you can manipulate and not just look at. The other thing is don’t use the word “don’t” too often. Give the leeway to do things which might even look a little hazardous to you as a parent. Learning is always hazardous. 

Watch the interview

Did you find any typos in this text? We would appreciate your assistance in identifying any errors and to let us know. Thank you for taking the time to report the errors by sending us an e-mail.