Immersing himself in alternate lifestyles and hilarious experiments (usually with himself as the guinea pig), writer A.J. Jacobs tests the limits of behavior, customs, culture -- and reports back on the wisdom and practical knowledge he's gained.
Dean Ornish is a clinical professor at UCSF and founder of the Preventive Medicine Research Institute. He's a leading expert on fighting illness -- particularly heart disease with dietary and lifestyle changes.
Peter Diamandis runs the X Prize Foundation, which offers large cash incentive prizes to inventors who can solve grand challenges like space flight, low-cost mobile medical diagnostics and oil spill cleanup. He is the chair of Singularity University, which teaches executives and grad students about exponentially growing technologies.