Chapter+1+Introduction

Chapter+1+Introduction - Introduction 1 Chapter One...

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Introduction 1 Chapter One INTRODUCTION In this book we explore the origin and evolution of Earth, from the beginning of our known universe at the Big Bang, through the formation of the elements in stars, to the formation of our solar system, and the evolution of our planet that became the home to life, and ultimately to human beings that can question and begin to understand the universal processes from which we are derived. Viewed on the largest scale, this story is the central story of our existence. It relates us to the beginning, to all of natural history, and to everything we can observe. While this book has as a primary aim to accurately present some of our current scientiF c knowledge on these topics, a secondary aim is to encourage a different scale of thinking than is normal to us—how we are derived from and related to a larger world. One of our aims as we explore the story of our existence is to include the detailed understanding that comes from the smallest scales—how atoms are formed, how molecules combine and so on—and also to relate to the larger scales, ultimately the largest scale we know of, the universe itself. We want to consider not only what Earth is made of and how its parts function, but also how the arising of our habitable planet relates to the larger scales of solar system and Universe. In this exploration, the range of scales we will need to encompass is almost unfathomable, from the atomic to the universal. As we will discover in Chapter 2, the age of the universe is roughly 15 billion years. The time of the atomic reactions that are involved in the creation of matter can be nanoseconds (0.000000001 seconds). Dealing with such huge and small numbers requires exponential notation, so we will write and refer to these numbers in exponential notation, 15 * 10 9 years and 10 -9 seconds. Knowing that there are 3*10 7 seconds in a year, we F nd that we will discuss events that differ in time by more than 26 orders of magnitude. We can mention this range of scales in a single sentence—the enormity of it is difF cult to comprehend. An even greater dimensional range is involved when we consider distances. Leaving apart fundamental particles, the size of the hydrogen nucleus—the starting point for all atoms—is 10 -10 meters. A light year is a measure of distance in astronomy referring to the distance light travels in a year. Since the speed of light is 10 8 meters/second times multiplying by the 3*10 7 seconds in a year, a light year is 3*10 16 meters. The nearest star is three light years away, the Milky Way is 100,000 light years across, and the universe is estimated to be billions of light years in diameter, Hence our task encompasses 10 35 in terms of distance. The difF
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Chapter+1+Introduction - Introduction 1 Chapter One...

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