Sara Imari Walker, an astrobiologist and theoretical physicist, delves into the scientific nuances of life and its origins. She engages in thought-provoking discussions on the inadequacies of traditional definitions of life and the intersection of biology and technology. With insights into constructor and assembly theory, Walker explores how complexity evolves. The conversation touches on the Fermi Paradox and the likelihood of extraterrestrial life, highlighting philosophical implications and the continuous quest for understanding what constitutes existence.
Current definitions of life struggle to classify entities like viruses and technology due to their unique replicative and self-sustaining characteristics.
The role of information is crucial in understanding life, as it influences the complexity and evolutionary functions of biological systems.
The Fermi paradox highlights the rarity of life and the specific conditions needed for its emergence, suggesting advanced civilizations may be unobservable.
Deep dives
The Nature of Life and Its Definitions
Current definitions of life often focus on identifying it as a self-sustaining chemical system capable of Darwinian evolution. However, these definitions present various edge cases that complicate the classification of certain entities, such as viruses or mules, as alive or not. For instance, while viruses can replicate within host cells, they lack the self-sustaining properties when outside a host. Additionally, the debate extends to whether technology might qualify as a form of life and how the evolving definitions highlight the inadequacies of strict classifications.
The Role of Information in Defining Life
Information plays a crucial role in distinguishing living systems from non-living ones, as it underpins the complexity and functionality of biological structures. The speaker suggests that understanding life requires recognizing how information becomes a physical feature of evolving systems, imparting causality to otherwise inert materials. This perspective shifts the understanding of information from a mere abstract concept to something with tangible physicality. Consequently, complex life forms may emerge due to information being both constructed and influential in evolutionary processes.
Assembly and Constructor Theory
Assembly theory asserts that complex structures cannot arise spontaneously and require prior constituents for their construction, emphasizing a hierarchical relationship between objects. The theory connects to constructor theory as both explore the nature of causation and the conditions necessary for the existence of complex systems. By analyzing tasks and their possibilities instead of focusing solely on initial conditions or laws of motion, these theories aim to redefine understanding in a way that aligns more closely with observed realities in evolutionary biology. This approach may lead to significant insights into the emergence of life as complex systems evolve within specific constraints.
The Fermi Paradox and the Origin of Life
The Fermi paradox raises profound questions about why, despite the vastness of the universe, advanced extraterrestrial civilizations have not been detected. The speaker posits that life may be exceedingly rare due to the specific conditions required for its emergence, influenced heavily by geological and atmospheric factors that differ across planets. Even if life exists, its complexity may be constrained by the unique histories of each planet's evolutionary pathway. As research into the origin of life progresses, understanding its probabilities may help clarify whether we are indeed alone or whether successful civilizations are simply unobservable.
Implications of Discovery on Extraterrestrial Life
Finding evidence of even simple life forms in our solar system, such as RNA or proteins, would dramatically alter perceptions of life’s emergence and evolution. The implications of such a discovery could challenge existing theories about life's uniqueness on Earth, prompting further inquiries into why advanced forms of life might be absent despite the prevalence of simpler life. If simple life can arise under suitable conditions elsewhere, it raises the question of what prevents it from advancing in complexity. Thus, the journey to understanding life involves not only exploring other planets but also delving into the fundamental mechanisms that govern life’s evolutionary trajectories.
Sam Harris speaks with Sara Imari Walker about a scientific understanding of life. They discuss the contributions of physics to this topic, Erwin Schrödinger, the inadequacy of standard definitions of life, the prospect of "artificial" life, the role of information, constructor theory, assembly theory, the space of all possible structures, a "block universe," the existence of abstract objects like numbers, the Fermi paradox, the likelihood of life elsewhere in the universe, experiments that could decide how likely life is to emerge, the possibility of a Great Filter, the number of Earth-like worlds, and other topics.
Sara Imari Walker is an astrobiologist and theoretical physicist. She is the deputy director of the Beyond Center for Fundamental Concepts in Science and a professor in the School of Earth and Space Exploration at Arizona State University. She is also a fellow of the Berggruen Institute and a member of the external faculty at the Santa Fe Institute. She is a recipient of the Stanley L. Miller Early-Career Award for her research on the origin of life, and her research team at ASU is internationally regarded as being among the leading labs aiming to build a fundamental theory for understanding what life is. Her research has been featured in Scientific American, Quanta Magazine, and a variety of other international outlets. Her book, Life as No One Knows It: The Physics of Life's Emergence, is available now.
Learning how to train your mind is the single greatest investment you can make in life. That’s why Sam Harris created the Waking Up app. From rational mindfulness practice to lessons on some of life’s most important topics, join Sam as he demystifies the practice of meditation and explores the theory behind it.
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