Acknowledgments I would like to thank my editor, David Heath, for his astute guidance in the preparation of
this book, and Charles Moomaw for his extensive technical assistance. I am grateful to Dr.
Peter Moomaw for lending his scientific expertise and to artist Carol Kelley for graciously
allowing her artwork to be included in this book. I greatly appreciate the participation of
Andrew, Ashley, Caroline, Charlie, Emily, Max, Nancy, Peter, Sonya, Tamara, and Vivian,
who appear in the photographs.