Jayme Tiomno : a life for science a life for Brazil Prologue Growing up Student Days in Rio de Janeiro. Medicine becomes Physics A new world of subatomic particles The Young Researcher Princeton Elisa The CBPF Research at the CBPF A New Decade A utopian Academy The Military Regime Exile PUC The Amnesty Researcher emeritus Conclusion. The new Century Epilogue. Jayme Tiomno (1920 2011) was one of the most influential Brazilian physicists of the 20th century interacting with many of the renowned physicists of his time including John Wheeler and Richard Feynman Eugene Wigner Chen Ning Yang David Bohm Murray Gell Mann Remo Ruffini Abdus Salam and many others. This biography tells the sometimes romantic often discouraging but finally optimistic story of a dedicated scientist and educator from a developing country who made important contributions to particle physics gravitation cosmology and field theory and to the advancement of science and of scientific education in many institutions in Brazil and elsewhere. Drawing on unpublished documents from archives in Brazil and the US as well as private sources the book traces Tiomnos long life following his role in the establishment of various research facilities and his tribulations during the Brazilian military dictatorship. It presents a story of progress and setbacks in advancing science in Brazil and beyond and of the persistence and dedication of a talented physicist who spent his life in search of scientific truth.