Absolutely Small: How Quantum Theory Explains Our Everyday World

Preface

IF YOU ARE READING THIS, you probably fall into one of two broad

categories of people. You may be one of my colleagues who is

steeped in the mysteries of quantum theory and wants to see how

someone writes a serious book on quantum theory with no math.

Or, you may be one of the vast majority of people who look at the

world around them without a clear view of why many things in

everyday life are the way they are. These many things are not insignificant

aspects of our environment that might be overlooked.

Rather, they are important features of the world that are never explicated

because they are seemingly beyond comprehension. What

gives materials color, why does copper wire conduct electricity but

glass doesn’t, what is a trans fat anyway, and why is carbon dioxide

a greenhouse gas while oxygen and nitrogen aren’t? This lack of a

picture of how things work arises from a seemingly insurmountable

barrier to understanding. Usually that barrier is mathematics. To

answer the questions posed above—and many more—requires an

understanding of quantum theory, but it actually doesn’t require

mathematics.

This book will develop your quantum mechanics intuition,

which will fundamentally change the way you view the world. You

have an intuition for mechanics, but the mechanics you know is

what we refer to as classical mechanics. When someone hits a long

drive baseball, you know it goes up for a while, then the path turns

over and the ball falls back to Earth. You know if the ball is hit

harder, it takes off faster and will go farther before it hits the

ground. Why does the ball behave this way? Because gravity is pulling

it back to Earth. When you see the moon, you know it is orbiting

the Earth. Why? Because gravity attracts the moon to the Earth. You

don’t sit down and start solving Newton’s equations to calculate

what is going on. You know from everyday experience that apples

fall down not up and that if your car is going faster it will take

longer to stop. However, you don’t know from everyday experience

why cherries are red and blueberries are blue. Color is intrinsically

dependent on the quantum mechanical description of molecules.

Everyday experience does not prepare you to understand the nature

of things around you that depend on quantum phenomena. As

mentioned here and detailed in the book, understanding features of

everyday life, such as color or electricity, requires a quantum theory

view of nature

Why no math? Imagine if this book contained discussions of a

topic that started in English, jumped into Latin, then turned back to

English. Then imagine that this jumping happened every time the

details of an explanation were introduced. The language jumping is

what occurs in books on quantum theory, except that instead of

jumping from English to Latin, it jumps from English to math. In

a hard core quantum mechanics book (for example, my own text,

Elements of Quantum Mechanics [Oxford University Press, 2001]),

you will find things like, ‘‘the interactions are described by the following

set of coupled differential equations.’’ After the equations,

the text reads, ‘‘the solutions are,’’ and more equations appear. In

contrast, the presentation in this book is descriptive. Diagrams replace

the many equations, with the exception of some small algebraic

equations—and these simple equations are explained in detail.

Even without the usual overflow of math, the fundamental philosophical

and conceptual basis for and applications of quantum theory

are thoroughly developed. Therefore, anyone can come away

with an understanding of quantum theory and a deeper understanding

of the world around us. If you know a good deal of math, this

book is still appropriate. You will acquire the conceptual understanding

necessary to move on to a mathematical presentation of

quantum theory. If you are willing to do some mental gymnastics,

but no math, this book will provide you with the fundamentals of

quantum theory, with applications to atomic and molecular matter.