This is the fifth in a series about the human side of science, drawn from interviews with 27 cosmologists. Earlier posts explored the origin of the project, the method, wonder and beauty, and craft. This one is about something that surprised me in the data: these scientists don’t just study different things. They think in fundamentally different ways.

04: How scientists think

“I tend to think visually, I believe, rather than, say, in equations. I don’t know—how else do you think, besides in images?”—Philip Peebles

“Usually I tend to think more in terms of equations… I tend to work in terms of mathematical or physical concepts rather than visual concepts.”—Joseph Silk

“I can’t evaluate a model unless I can generate a mental movie of what’s happening and what’s moving where.”—Sandra Faber

Three cosmologists. Three completely different cognitive machines. Peebles cannot imagine thinking any way other than visually. Silk works in equations, not pictures. Faber needs a movie running in her head before she can judge whether a model is any good. They share a discipline, a set of problems, even some of the same data. But the internal experience of doing the work is nothing alike.

The range is wider than any simple visual-versus-verbal axis can capture. Roger Penrose visualizes in multiple dimensions, building models from conformal maps and spacetime diagrams. (Not surprising, Penrose and his father created the impossible triangle, which inspired some of Escher‘s most mind-bending work. Incidentally I created, what I think is an original visual illusion based on this very impossible triangle.) James Gunn, on the other hand, makes mental movies that run “always going backwards” in time. Edwin Turner shifts perspective to be inside the phenomenon: “The trick there is to not think about it as something you’re outside of looking at—you know a little thing going ‘bang’—but to think of something you’re inside of.” John Huchra carries a mental atlas of galaxies: “I have almost a catalogue of NGC galaxies sitting in my head.” Robert Dicke thinks through analogies. Martin Rees approaches cosmology the way a historian approaches the past. These are not minor stylistic preferences. They are different architectures for making sense of the same universe.

Stephen Hawking’s case is especially striking. His cognitive mode is not a preference but a necessity shaped by his body: “I really have to be able to visualize a problem… There are plenty of people who can manipulate equations better than me, because it is difficult for me to write them down… I do, however, have intuition about geometry.” Physical constraint produced a distinctive way of knowing—and that way of knowing produced some of the most important results in the field.

Margaret Geller adds a developmental dimension. Her father, a crystallographer, trained her spatial cognition from childhood, showing her crystal structure models over and over: “He would say it again and again and again. And finally, I would be able to see those spatial relations.” She believes that training directly enabled her later recognition of the cosmic bubble structure that others had looked at and missed. Cognitive mode is not fixed at birth. It can be cultivated—but only if someone realizes it needs cultivating.

And Fred Hoyle, one of the most creative minds in twentieth-century astrophysics, admits: “I was never a very good geometer. I had to do all my geometry algebraically. I’m not very good at visual imagery.” No deficit there. Just a different machine doing the same work.

What is interesting is how blind some of these scientists are to the fact that others think very differently than they do. This is best expressed in a question asked Peebles: “How else do you think, besides in images?” I do not think he was being dismissive. He genuinely could not conceive of a mind that worked differently from his own. And that invisible assumption—that everyone’s cognitive world is like yours—may be the most important finding in this entire analysis. It has implications far beyond cosmology, for how we teach, how we design learning environments, how we understand the people sitting next to us. I’ve written about this at length elsewhere, and it deserves a longer conversation than this essay can give it. My own work has always crossed these boundaries in small ways—ambigrams that live between the visual and the verbal, mathematical poetry that fuses number and language—and I suspect that’s part of why this theme in the data connected with me so deeply. The boundaries have always seemed arbitrary. These twenty-seven cosmologists support the ideas that the mind has more ways of working than we often realize, and that most of us are blind to these other ways of thinking.

Next: what drives these scientists forward, and the very different ways they live with not knowing: The Drive