Physicist Anthony Aguirre goes deep in 'Cosmological Koans' book

book cover
Anthony Aguirre
Anthony Aguirre

In his new book, Cosmological Koans: A Journey to the Heart of Physical Reality, physicist Anthony Aguirre explores deep questions about the nature of reality, using an approach inspired by Zen koans to take the reader on a thought-provoking tour of the cosmos and the core ideas of modern physics.

In Zen Buddhism, koans are short parables or questions meant to confront the practitioner with the inadequacy of conventional concepts and habits of thought. Similarly, Aguirre's "cosmological koans" confront the reader with the unexpected nature of the world as described by physics and the mind-boggling ways in which it differs from our subjective experience or intuitive understanding of things.

"I wanted to convey that sense of mystery and wonder that comes from seeing reality in a new way," said Aguirre, a professor of physics and holder of the Faggin Family Presidential Chair for the Physics of Information at UC Santa Cruz.

The book covers a wide range of topics, woven together with a fictional story line that recounts a journey from Italy to Japan. Multiple universes, the nature of time, the meaning of quantum theory, and entropy and information are among the subjects explored in short chapters that manage to convey mind-bending ideas in a way that is accessible and entertaining.

The topics include some of the most challenging open questions in cosmology and physics, as well as concepts that have long been settled science yet remain disturbingly counterintuitive. With respect to the enduring mystery of time, for example, Einstein showed that there is no universal "now"—in other words, different observers can have different perceptions of whether two events are simultaneous.

Aguirre celebrates the accomplishments of modern physics in penetrating the mysteries of nature, while showing how many thorny questions remain unsettled. "We should take credit for how well we've done in understanding reality, while acknowledging that a lot of those concepts are more tricky and slippery than you might think."

The role of the observer and the connections between what happens in the outer world and the inner experience of conscious observers is a recurring theme in the book.

"Things we tend to view as purely objective are more subjective or dependent on our perspective than we think," Aguirre said. "There is a sense in which we as observers are co-creators of the outside world. But that doesn't mean anything goes—there is a reality that pushes back on us. You can't just walk off a cliff and pretend there is no gravity."

Another key idea in the book is the importance of information as a coequal constituent of the universe along with matter and energy. The content of the book was inspired not only by Aguirre's own research, which covers a variety of topics in theoretical cosmology, but also by his work as associate scientific director of the Foundational Questions Institute, which supports research on innovative ideas in cosmology and physics that are unlikely to be supported by conventional funding sources.

MIT physicist Max Tegmark, who co-founded the institute with Aguirre, had high praise for Cosmological Koans. "Reading it won't leave you with all the answers (we physicists are still searching for them), but it will leave you with a deepened sense of mystery, awe, and appreciation both for your universe and for your own life and experience therein," he wrote.

Aguirre will give a public talk on Tuesday, June 18, at the UC Santa Cruz Silicon Valley Campus in Santa Clara as part of the Kraw Lecture Series on Science and Technology. For more information and registration, visit