9781422283295

Introduction

set of equations can describe the actions of some things, but does not work on others. The problem here is not physics, though—it’s the limits of human understanding. Physics is often called the most basic of all the sciences. Chemistry and biology also explain how natural systems work and interact, but they are still based on the funda- mental laws of physics. Without these underpinnings, none of it makes sense. Over thousands of years, humans have learned to adapt to the laws of physics without even thinking about it. We know that it hurts when falling objects hit us on the head, but we rarely put it in the form of an equation about accel- eration. We know that machines get hot when they operate, but we don’t usually explain it in terms of thermodynamics. Over those same thousands of years, though, there have been people who thought deeply about such things—and more. They asked questions such as: How did the universe begin? Where and when do space and time merge together? Why does matter sometimes act like it’s a bunch of parti- cles, while other times it moves in waves? Why does matter even matter? Does a star exploding trillions of miles away have any significance in our lives? As scientists have probed into the laws of physics, they have learned more details about how they work. Those dis- coveries have made enormous impacts on our lives. Knowl- edge of physics is critical to understanding how machines operate, for example. Without it, humans would not have been able to invent an airplane that would actually stay in

Introduction

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