Life On Earth-like Planets: Gaia And Her Sisters

Book excerpt: From its ancient Greek roots to Lovelock's groundbreaking 1979 book, the concept of Gaia has evolved to depict Earth as a single, intricate organism sustaining life through the interplay of its organic and inorganic elements. From the Hadean epoch, where life's emergence radically transformed our planet, to the present, Earth stands as our sole model for understanding life's potential on other Earth-like worlds. While the lifeforms that evolve on Earth-like planets would not necessarily be identical to those on Earth, they must satisfy the same constraints. These constraints are the central subject of this book.Exploring Earth's early conditions during the Hadean era, when oceans dominated and oxygen was scarce, the book illuminates the daunting challenges life faced. Yet, life found its foothold, driven by thermodynamic favorability amidst high tides and shorter days, laying the groundwork for its inevitable emergence. Delving into the fundamental principles of matter and quantum mechanics, the book further highlights life's origin as a product of complex molecular interactions overcoming energy constraints. With insights into the statistical approach to life's origins and the fallacies in estimating life's probability on other planets, the book redefines life as a natural process governed by universal laws.As an underlying theme of this book, life's evolution towards complexity is portrayed as a harmonious extension of non-living processes, challenging the limited conventional view of thermodynamics. Readers will come to appreciate that Earth is a testament to life's resilience and the intricate tapestry woven by biochemical forces across the cosmos.