Geologist Walter Alvarez lands a job at Berkeley, where his father, the renowned quantum physicist Luis Alvarez, also works. Luis, in addition to having made fundamental contributions to the invention of the atomic bomb and particle accelerators, also revealed, using muon detectors, that the Egyptian pyramids are solid inside, except for the access corridors. This time, the meeting with his son will lead to another enormously fruitful cross-fertilization between different fields: the soil samples taken in Gubbio by Walter, when analyzed for iridium as suggested by Luis, meet the full scale. Those samples have something extraterrestrial about them. Further analyses of other samples around the world will lead to the June 1980 article, in which the Alvarezes will reveal the discovery of the reason for the sudden disappearance of the dinosaurs 65 million years ago.
