Mario Bertolotti received his degree in Physics from the University of Roma, Italy and became full professor of physics at the Engineering Faculty of the University of Roma "La Sapienza" from 1970 until 2008, when he retired. After a short period at CERN, Ginevra he returned to Italy and started research on lasers, light-matter interactions, nonlinear optics, etc. He is the author of about 500 papers on peer reviewed physics journals. He is fellow of IOP, American Optical Society, Italian Physical Society, Italian Optical and Photonic Society of which he has been the president, European Optical Society in which he held and is holding several positions. He is member of European Physical Society, where he held positions several years ago. Mario Bertolotti has been member of scientific committee in several journals. He was editor of the journal Pure and Applied Optics edited by IOP, he is editor of the Journal of the European Optical Society: Rapid Publications (JEOS:RP), an electronic journal. He has been director of several summer schools in Erice, and other places. He was also interested in the hystoric developments of physics and wrote two books on the history of lasers. Cosmic rays were a subject of his interest altough he never worked actively in the field. The books on the history of lasers are: M.Bertolotti, Maser and Laser: an Historical Approach, Adam Hilger, Bristol 1983 M.Bertolotti, Storia del laser, Boringhieri, Torino 1999 M.Bertolotti, The history of the laser, IOP Publishing Ltd 2005 (translation of the Italian book)

• Prehistory - The electron, the proton and X-rays.- Prehistory - Radioactivity.- Cosmic rays - The antefacts.- The discovery - Victor F. Hess and the balloon flights.- The confirmation - Robert Millikan and the  “birth cry” of the borning atoms.- A turning point - Things are not as they look.- The earth magnetic field and the geomagnetic effects.- The positive electron.- The electromagnetic showers.- The muon.- The discovery of the π-meson, nuclear emulsions and the first “strange” particles.- The extended showers.- Nuclear stars.- The neutrino: elusive and capricious particles able to come from very far away.- What are the primary cosmic rays?.- The origin of cosmic rays.- X- and gamma rays from space.