Book contents
- Frontmatter
- Contents
- Preface to the Second Edition
- Preface to the First Edition
- 1 An Explanation for the Absence of Extraterrestrials on Earth
- 2 One Attempt to Find Where They Are: NASA's High Resolution Microwave Survey
- 3 An Examination of Claims that Extraterrestrial Visitors to Earth Are Being Observed
- 4 The Likelihood of Interstellar Colonization, and the Absence of Its Evidence
- 5 Pre-emption of the Galaxy by the First Advanced Civilization
- 6 Stellar Evolution: Motivation for Mass Interstellar Migrations
- 7 Interstellar Propulsion Systems
- 8 Interstellar Travel: A Review
- 9 Settlements in Space, and Interstellar Travel
- 10 Terraforming
- 11 Estimates of Expansion Timescales
- 12 A Search for Tritium Sources in Our Solar System May Reveal the Presence of Space Probes from Other Stellar Systems
- 13 Primordial Organic Cosmochemistry
- 14 Chance and the Origin of Life
- 15 The RNA World: Life before DNA and Protein
- 16 The Search for Extraterrestrial Intelligence
- 17 Alone in a Crowded Universe
- 18 Possible Forms of Life in Environments Very Different from the Earth
- 19 Cosmological SETI Frequency Standards
- 20 Galactic Chemical Evolution: Implications for the Existence of Habitable Planets
- 21 The Frequency of Planetary Systems in the Galaxy
- 22 Atmospheric Evolution, the Drake Equation and DNA: Sparse Life in an Infinite Universe
- About the Editors and Contributors
- Author Index
- Subject Index
14 - Chance and the Origin of Life
Published online by Cambridge University Press: 20 October 2009
- Frontmatter
- Contents
- Preface to the Second Edition
- Preface to the First Edition
- 1 An Explanation for the Absence of Extraterrestrials on Earth
- 2 One Attempt to Find Where They Are: NASA's High Resolution Microwave Survey
- 3 An Examination of Claims that Extraterrestrial Visitors to Earth Are Being Observed
- 4 The Likelihood of Interstellar Colonization, and the Absence of Its Evidence
- 5 Pre-emption of the Galaxy by the First Advanced Civilization
- 6 Stellar Evolution: Motivation for Mass Interstellar Migrations
- 7 Interstellar Propulsion Systems
- 8 Interstellar Travel: A Review
- 9 Settlements in Space, and Interstellar Travel
- 10 Terraforming
- 11 Estimates of Expansion Timescales
- 12 A Search for Tritium Sources in Our Solar System May Reveal the Presence of Space Probes from Other Stellar Systems
- 13 Primordial Organic Cosmochemistry
- 14 Chance and the Origin of Life
- 15 The RNA World: Life before DNA and Protein
- 16 The Search for Extraterrestrial Intelligence
- 17 Alone in a Crowded Universe
- 18 Possible Forms of Life in Environments Very Different from the Earth
- 19 Cosmological SETI Frequency Standards
- 20 Galactic Chemical Evolution: Implications for the Existence of Habitable Planets
- 21 The Frequency of Planetary Systems in the Galaxy
- 22 Atmospheric Evolution, the Drake Equation and DNA: Sparse Life in an Infinite Universe
- About the Editors and Contributors
- Author Index
- Subject Index
Summary
Introduction
It is a widely held view that life will arise spontaneously on the surface of any planet that provides a suitable physical and chemical environment. This belief is saved from tautology by the generously broad definitions of ‘suitable’ that abound in discussions of the origin of life. Indeed it is almost sufficient to require only that liquid water occur on the planet's surface, for then it follows that the atmospheric pressure and ambient temperature will be in ranges that promote a rich variety of organic reactions.
On the ancient Earth, as today, the simultaneous presence of the three states of matter along terrestrial shorelines provided reaction sites and macroscopic transport for most of the planet's chemicals. The temperature was low enough to confer a substantial lifetime on thermodynamically improbable molecules formed in sunlit waters, yet high enough to give speed to the processes of chemistry, and to the evolution of life. The importance of speed in chemistry and evolution is emphasized by the reflection that a cooler planet than ours, where reaction rates were one-fourth as great, would see its sun burn away from the main sequence of stars before it witnessed intelligent life.
This standard scenario of life's origin has been strengthened greatly by the outcome of laboratory experiments in geochemistry (Fox & Dose, 1972). They show that the assumed primitive molecules of our planet's early atmosphere, if supplied with free energy, could form sugars, amino acids, purines, pyrimidines and other life-related organic substances.
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- Information
- ExtraterrestrialsWhere Are They?, pp. 125 - 138Publisher: Cambridge University PressPrint publication year: 1995