Lex Fridman Podcast #198 – Sara Walker: The Origin of Life on Earth and Alien Worlds
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Jul 9, 2021 
Sara Walker, an astrobiologist and theoretical physicist, dives into the mysteries of life's origins and the intriguing possibility of extraterrestrial life. She discusses the RNA world hypothesis and the role of hydrothermal vents in life's early emergence. The conversation also explores concepts like the shadow biosphere and panspermia, questioning how we define life. Walker highlights innovative strategies for detecting alien life, emphasizing a holistic understanding of biological complexity. Her insights intertwine philosophy with science, reflecting on existence and our place in the universe.
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RNA World Hypothesis
- The RNA world hypothesis suggests RNA was the first genetic material, playing both genetic and catalytic roles.
- This theory posits that a self-replicating RNA molecule emerged, kickstarting life's evolution.
Two Origins of Life Views
- Two main hypotheses for life's origin focus on genetics (RNA world) and metabolism (energy and self-organization).
- These views are often favored by biologists and physicists/geochemists, respectively.
Panspermia's Limitations
- Panspermia, the idea that life arrived on Earth from elsewhere, is a plausible hypothesis, especially with microbial life.
- However, finding identical life on other planets wouldn't reveal much about life's universal origins.