1900: Discovery of the radioactivity by Becquerel, Pierre and Marie Curie.
First years: Max Plank, discovery of quantum mechanics. Development of explosion motor, diesel, motor racing, cinematography, wireless telegraph, electric railways, intra oceanic telephones, aviation, conquest of the Poles, Great Britain, the first power of an immense sea empire, “The Young Ladies of Avignon”, by Picasso, and “The Rite of Spring,” by Igor Stravinsky.