In his final years, Richard Feynman's curiosity took him to some surprising places. We hear from his companions on the trips he took — and one he wasn’t able to. (Part three of a three-part series.) SOURCES: Alan Alda, actor and screenwriter.Barbara Berg, friend of Richard Feynman.Helen Czerski, physicist and oceanographer at University College London.Michelle Feynman, photographer and daughter of Richard Feynman.Cheryl Haley, friend of Richard Feynman.Debby Harlow, friend of Richard Feynman.Ralph Leighton, biographer and film producer.Charles Mann, science journalist and author.John Preskill, professor of theoretical physics at the California Institute of Technology.Lisa Randall, professor of theoretical particle physics and cosmology at Harvard University.Christopher Sykes, documentary filmmaker.Stephen Wolfram, founder and C.E.O. of Wolfram Research; creator of Mathematica, Wolfram|Alpha, and the Wolfram Language. RESOURCES: Quantum Man: Richard Feynman's Life in Science, by Lawrence M. Krauss (2011).Perfectly Reasonable Deviations From the Beaten Track: Selected Letters of Richard P. Feynman, edited by Michelle Feynman (2005).The Pleasure of Finding Things Out, by Richard Feynman (1999).The Demon-Haunted World: Science as a Candle in the Dark, by Carl Sagan and Ann Druyan (1995).Genius: The Life and Science of Richard Feynman, by James Gleick (1992).The Quest for Tannu Tuva, by Christopher Sykes (1988)“What Do You Care What Other People Think?” by Richard Feynman and Ralph Leighton (1988).The Second Creation: Makers of the Revolution in Twentieth-century Physics, by Robert Crease and Charles Mann (1986).Surely You're Joking, Mr. Feynman!, by Richard Feynman and Ralph Leighton (1985).Fun to Imagine, BBC docuseries (1983). EXTRAS: “The Brilliant Mr. Feynman,” by Freakonomics Radio (2024).“The Curious Mr. Feynman,” by Freakonomics Radio (2024).