First, I'd like to thank Bill Frucht, senior editor at Basic Books, who played an essential role in the genesis and development of this book. To him goes credit for the original concept, much of the organization, and numerous intelligent and insightful suggestions.
For providing me with information, opinions and advice, I'm grateful in particular to: Gustaf Arrhenius, Scripps Institution of Oceanography; Mark Bedau, Reed College, Portland, Oregon; Max Bernstein, NASA Ames Research Center; Jay Brandes, University of Texas at Austin; Simon Conway Morris, University of Cambridge; Alex Ellery, Queen Mary and Westfield College, London; Clark Friend, Oxford Brookes University; Guillermo Gonzalez, University of Washington; Joseph Kirschvinck, California Institute of Technology; Geoffrey Marcy, University of California, Berkeley; Stephen Mojzsis, University of California, Los Angeles; Thomas Ray, University of Oklahoma; Gregory Schmidt, NASA Ames Research Center; Victor Tejfel, Fesenkov Astrophysical Institute; Hojatollah Vali, McGill University; and Peter Ward, University of Washington, Seattle. Any mistakes or misinterpretations that may have crept into the text are, of course, my responsibility alone.
As always, my agent Patricia van der Leun worked tirelessly behind the scenes and provided support above and beyond the call of duty. Thank you again, Patricia.
Last, and most of all, I thank my family. Only through their support and encouragement, over many years, have I been lucky enough to pursue a fantasy career instead of a "real job."