In 1980, Walter Alvarez and his team published their hypothesis about the dinosaur extinction. A huge asteroid impacted Earth 65 million years ago and eliminated almost all species in the Earth, including dinosaurs. After a surprising observation in the evidences related to plate tectonic, Walter started to ask questions. He consulted his father the physicist and noble prize winning Luis Alvarez. Alvarez analyzed a rock sample found by Walter at the Cretaceous-Tertiary boundary in Italy, and he discovered a rare element iridium in the clay, rare in the Earth, but abundant in comets and asteroids. The scientist community followed Walter’s scientific journey. First a peer review inspired them to new assumptions and new hypothesis. Second they
