Dr. Sara Imari Walker is an astrobiologist and theoretical physicist pioneering ideas about the origins of life. She discusses the limitations of traditional definitions of life and introduces assembly theory, which examines the complexity of molecular structures. The conversation delves into the intersection of physics and biology, the implications of embryology for understanding life, and the exciting prospect of alien intelligence. Sara also shares thoughts on technology's role in discovering new forms of life, inspiring a fresh perspective on existence.
Dr. Sara Walker advocates for a shift from defining life by rigid characteristics to understanding it through its fundamental processes and actions.
Walker argues that traditional physics fails to capture the dynamic evolution of life, necessitating a new approach that considers historical contingencies.
Assembly theory highlights that only living systems can generate complex biological molecules, emphasizing the role of life's history in creating complexity.
Deep dives
Defining Life Through Action
Traditional definitions of life often focus on characteristics such as reproduction, metabolism, or self-sustaining systems, but these criteria often fall short when considering exceptions like sterile mules. Astrobiologist Sarah Walker suggests that instead of attempting to define what life is, we should focus on what life does. This shift in perspective emphasizes the processes of life, rather than rigid classifications that can lead to inconsistencies. Walker’s insights indicate that understanding life’s actions may lead to a more meaningful comprehension of existence itself.
Physics in Understanding Life
Walker discusses how traditional physics, which relies on fixed laws and initial conditions, is inadequate for explaining the dynamic nature of life. Instead, she advocates for the development of a new physics that accommodates the historical and path-dependent nature of living systems. Life, uniquely characterized by the evolution of complex, adaptive structures, requires a different approach that considers the contingencies of its developmental history. This understanding could revolutionize our grasp of both physical laws and biological processes.
Assembly Theory and Complexity
Assembly theory posits that life is the only mechanism for generating complex objects, with complexity being defined through an 'assembly index' that indicates how structures are built from simpler components. Walker, alongside collaborator Lee Cronin, argues that the universe lacks the capacity to spontaneously produce complex biological molecules without the influence of living processes. Experiments demonstrate that above a certain complexity threshold, only molecules produced by living systems can exist, highlighting the importance of historical and selective processes in the emergence of life. Thus, assembly theory provides a robust framework for understanding the intricate relationship between complexity and life.
The Evolving Nature of Technology
Walker envisions technology as an extension of the evolutionary processes that gave rise to biological life, suggesting that our creations are informed by the complexities inherent in biological evolution. The development of tools and technologies allows for the conservation and recombination of information, leading to increasingly sophisticated systems. This perspective raises questions about the potential for technology to achieve a form of 'life' through the emergent properties of complex systems. The intersection of life and technology challenges conventional boundaries and encourages exploration of their co-evolution.
Search for Alien Life
In the quest to find extraterrestrial life, Walker proposes that we should look for life forms emerging from different causal histories than those on Earth. By utilizing assembly theory and advancing laboratory technologies, researchers can conduct systematic searches for alien life through experimental chemistry. This approach opens the possibility of discovering unique life forms that do not conform to Earth's evolutionary path, thus expanding our understanding of life in the universe. Walker emphasizes the importance of fundamental science as a means to navigate existential questions surrounding life, technology, and our place within the cosmos.
In this episode of Conversations, we sit down with Dr. Sara Walker, an astrobiologist and theoretical physicist who is reshaping the way we think about life. From her work on the origins of life to her innovative assembly theory, Sara takes us on a journey through the possibilities of discovering alien life and challenges some of the core tenets of biology and physics. This conversation will make you rethink not just how life began, but what life is and does.
