25 Acknowledgments
Our understanding of the work presented in this review was shaped by a series of annual meetings
named after the movie director Frank Capra. The first of these meetings took place in 1998 and was held at
Capra’s ranch in Southern California; the ranch now belongs to Caltech, Capra’s alma mater.
Subsequent meetings were held in Dublin (1999), Pasadena (2000), Potsdam (2001), State College
PA (2002), Kyoto (2003), Brownsville (2004), Oxford (2005), Milwaukee (2006), Hunstville
(2007), Orléans (2008), Bloomington (2009), and Waterloo (2010). At these meetings and
elsewhere we have enjoyed many instructive conversations with Paul Anderson, Warren Anderson,
Patrick Brady, Claude Barrabès, Leor Barack, Luc Blanchet, Lior Burko, Manuela Campanelli,
Marc Casals, Peter Diener, Steve Detweiler, Sam Dolan, Steve Drasco, Scott Field, Éanna
Flanagan, John Friedman, Ryuichi Fujita, Chad Galley, Darren Golbourn, Sam Gralla, Roland
Haas, Abraham Harte, Wataru Hikida, Tanja Hinderer, Scott Hughes, Werner Israel, Toby
Keidl, Dong-hoon Kim, Alexandre Le Tiec, Carlos Lousto, Eirini Messaritaki, Yasushi Mino,
Hiroyuki Nakano, Amos Ori, Larry Price, Eran Rosenthal, Norichika Sago, Misao Sasaki, Abhay
Shah, Carlos Sopuerta, Alessandro Spallicci, Hideyuki Tagoshi, Takahiro Tanaka, Jonathan
Thornburg, Bill Unruh, Bob Wald, Niels Warburton, Barry Wardell, Alan Wiseman, and Bernard
Whiting. This work was supported by the Natural Sciences and Engineering Research Council of
Canada.