Stanford Thesis: The Relevance of the Composition of Earth’s Early Atmosphere for Current Origin of Life Theories

A student requested that I post my Stanford master's thesis online. Enjoy!

The Relevance of the Composition of Earth’s Early Atmosphere for Current Origin of Life Theories

INTRODUCTION

Scientific research is able to proceed most quickly when the practitioners in a given field share the same paradigm: a common set of definitions, theories, and model experiments.  The distinction between observation and inference is not a sharp one because experimental results are interpreted through the paradigm, and such interpretations are usually consistent with the paradigm’s assumptions.

During periods of normal science, experimental results are easily made to fit the paradigm model, and research is fruitful because little effort is expended on the fundamental questions with which almost all of the workers are in agreement.

However, normal science is regularly punctuated by periods of crisis in which it is difficult to interpret a field’s experimental results in a way that is consistent with the paradigm.  During these times, the paradigm will be modified by various workers to attempt to explain anomalous data.  Different versions of the paradigm can become so numerous that the paradigm ceases to function as such, giving way to different schools of thought that each advocates its particular modifications.

The period of crisis continues until a satisfactory way is found to explain the anomalous results by one of the modified versions of the existing paradigm or by shifting to another paradigm altogether.  When a large number of practitioners has accepted the solution, normal science can resume because the fundamental assumptions are no longer being debated.

The origin of life field may currently be in a state of crisis. The rapid proliferation of competing theories combined with recent changes in our understanding of the atmosphere of the early earth have generated different, incompatible models of how life originated on the early earth. A brief review of these models is followed by a discussion of their dependence on our knowledge of earth’s early atmosphere.

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This is the Miller-Urey experiment that shows up in every high school and college biology textbook.
Is it an accurate model of the conditions that existed early in the history of our planet?