The Physics of Life: A New Theory Challenges Our Understanding of What Makes Us Alive

Sara Imari Walker, a professor of physics at Arizona State University, has written a new book, Life as No One Knows It: The Physics of Life’s Emergence, that challenges our understanding of what makes us alive. Walker argues that the standard set of theories we use to describe matter and forces are insufficient for understanding life, and that a new theoretical framework is needed.

Walker's work is part of a growing field known as “The Physics of Life,” which aims to understand what separates living from non-living systems. This is different from biophysics, which focuses on specific physics aspects of biological processes. Walker's approach, however, is more ambitious: she wants to understand the fundamental principles that govern life itself.

The Assembly Theory

Walker and her collaborators have developed Assembly Theory, which focuses on “selection” and is a fundamental physics account for the difference between life and non-life. The theory quantifies complexity by measuring how many unique steps are needed to build a molecular structure. By identifying complex patterns that signify biological processes, Assembly Theory could help scientists detect life forms on other worlds—even those that may not look like anything we’re familiar with on Earth. This new perspective has sparked both interest and controversy in the scientific community.

The Importance of New Ideas in Science

Walker argues that the scientific community has been too slow to embrace new ideas about the physics of life. She points to the example of Erwin Schrödinger’s 1944 book What is Life? which was one of the first attempts to understand life from a physics perspective. However, even after nearly 80 years, the question of “What is life?” remains unanswered.

“I think it may have been that the time wasn’t right to answer the question,” Walker said. “When Schrodinger wrote What is Life? it was the right time to ask the question, but we weren’t really adequately prepared to understand it. We didn’t yet know about, say, the molecular mechanisms of the cell.”

The Limitations of Existing Theories

Walker also criticizes the reliance on existing theories to explain life. She argues that the “bottom-up” approach, which seeks to derive everything from the fundamental laws of physics, is not always successful. In some cases, we need to start with a new idea and work our way down.

“I actually think it’s more parsimonious, more practical in some sense, to just approach the problem with fresh eyes as if nobody’s been able to answer it,” Walker said. “Just start from first principles and then ask how would you answer it. Then it might be a case that you come up with something that actually recovers standard physics. Then there’d be no need for a new explanation. But that exercise should be done in [and] of itself. And chances are you’re going uncover something new.”

The Importance of History in Science

Walker also emphasizes the importance of history in science. She argues that scientists often forget that they are living in a moment in history and that history is moving through them. This can lead to a resistance to new ideas and a tendency to think that existing theories are complete.

“We scientists generally just don’t think about the actual history,” Walker said. “We don’t think about ourselves living in a moment in history and history is moving through us.”

The Future of the Physics of Life

Walker’s book is a timely reminder that the scientific community needs to be more open to new ideas. She argues that the problem of life is not just a biological problem, but a fundamental physics problem. And to solve this problem, we need to be willing to challenge our assumptions and embrace new perspectives. “We have entered an era in which we are beginning to recognize that enormous data collection efforts alone will not solve fundamental questions about life,” Walker said. “Proper answers will require some abstract theorizing and old-fashioned peering inside of cells.”

Walker’s Assembly Theory is a step in the right direction. It is a new theoretical framework that could help us to understand the fundamental principles that govern life. And it could lead to a better understanding of the universe and our place in it. Only time will tell if the theory is correct, but it is certainly a fascinating and thought-provoking idea.

What Does the Future Hold?

Walker’s work is not just theoretical. She believes that Assembly Theory could have practical applications, such as helping to design new drugs or materials. The theory could also help us to understand extraterrestrial life, and how to find it.

“First contact with aliens will not be ‘an event, or even a piece of data’,” Walker said. “Rather, it will be a ‘cultural transformation in our understanding of and explanations for what life is.’ That is, Walker suggests that simply locating something that appears like a living thing outside of Earth is not nearly enough. A true understanding of unearthly life will require developing robust theories on what life is before the presumptive first-contact event.”

Moving Forward

Walker’s book is an important contribution to the ongoing discussion about the nature of life. It is a must-read for anyone interested in the origins of life, the search for extraterrestrial life, or the future of science. It is a powerful reminder that the pursuit of knowledge is a never-ending journey, and that we should always be open to new ideas and perspectives.