Every book is a collaboration, and this one more than others. There is much to be said about quantum mechanics, and there was definitely a temptation to say it all. That might have been a fun book to write but it would have been a tedious chore to read. I owe a variety of generous and insightful readers for their help in wrestling the manuscript down to something manageable and, hopefully, in parts, fun. I should specifically mention helpful comments from Nick Aceves, Dean Buonomano, Joseph Clark, Don Howard, Jens Jäger, Gia Mora, Jason Pollack, Daniel Ranard, Rob Reid, Grant Remmen, Alex Rosenberg, Landon Ross, Chip Sebens, Matt Strassler, and David Wallace. In ways stretching from small—offhandedly mentioning something in conversation that later ended up in the book—to large—reading every chapter and offering useful insights—these generous folks helped rescue me from writing a book that would not have been nearly as good.
I want to give special thanks to Scott Aaronson, who is the best test-reader a physicist/author could ask for, giving the text a thorough reading and offering invariably useful feedback on both substance and style. I’ll also mention Gia Mora again, because she was inexplicably omitted from the acknowledgments of The Big Picture, and I feel bad about that.
It goes without saying that I’ve learned an enormous amount about quantum mechanics and spacetime from a large number of extremely smart people over the years, and their influence pervades this book even if I didn’t talk specifically about the words written here. Many thanks go to David Albert, Ning Bao, Jeff Barrett, Charles Bennett, Adam Becker, Kim Boddy, Charles Cao, Aidan Chatwin-Davies, Sidney Coleman, Edward Farhi, Alan Guth, James Hartle, Jenann Ismael, Matthew Leifer, Seth Lloyd, Frank Maloney, Tim Maudlin, Spiros Michalakis, Alyssa Ney, Don Page, Alain Phares, John Preskill, Jess Reidel, Ashmeet Singh, Leonard Susskind, Lev Vaidman, Robert Wald, and Nicholas Warner, not to mention the numerous others I am doubtless forgetting.
Thanks as usual to my students and collaborators for tolerating my occasional absences while trying to finish the book. And thanks also to the students in 125C, the third quarter of Caltech’s course on quantum mechanics for juniors, who tolerated me teaching them about decoherence and entanglement rather than just the familiar routine of solving the Schrödinger equation over and over.
A million thanks to my editor at Dutton, Stephen Morrow, whose patience and insight were more sorely needed for this book than they have been in the past. He even let me include an entire chapter in dialogue form, although it’s possible I just wore him down. An author couldn’t imagine an editor who cared more about the quality of the final product, and much of the quality here is due to Stephen. Thanks also to my agents, Katinka Matson and John Brockman, who always make a process that could potentially be nerve-racking into something tolerable, possibly even enjoyable.
And the most thanks of all to Jennifer Ouellette, the perfect partner in writing and in life. Not only did she support me in countless ways along the journey, but she took time out of her own very demanding writing schedule to go through every page here carefully and offer invaluable insight and tough love. I didn’t delete nearly as much as she suggested, and probably the book is poorer thereby, but trust me, it’s way better than it was before she got to it.
Thanks also to Jennifer for bringing into our lives Ariel and Caliban, the best writing-partner cats an author could ask for. No actual cats were subjected to thought experiments during the composition of this book.