The Annus mirabilis papers (from Latin annus mīrābilis, "extraordinary year") are the papers of Albert Einstein published in the Annalen der Physik scientific journal in 1905. These four articles contributed substantially to the foundation of modern physics and changed views on space, time, mass, and energy. The annus mirabilis is often called the "miracle year" in English or Wunderjahr in German.
At the time the papers were written, Einstein did not have easy access to a complete set of scientific reference materials, although he did regularly read and contribute reviews to Annalen der Physik. Additionally, scientific colleagues available to discuss his theories were few. He worked as an examiner at the Patent Office in Bern, Switzerland, and he later said of a co-worker there, Michele Besso, that he "could not have found a better sounding board for his ideas in all of Europe". In addition, co-workers and the other members of the self-styled "Olympian Academy" (Maurice Solovine and Paul Habicht) and his wife, Mileva Marić had some influence on Einstein's work, but how much is unclear.
Through these papers, Einstein tackles some of the era's most important physics questions and problems. In 1900, a lecture titled "Nineteenth-Century Clouds over the Dynamical Theory of Heat and Light", by Lord Kelvin, suggested that physics had no satisfactory explanations for the results of the Michelson-Morley experiment and for black body radiation. As introduced, special relativity provided an account for the results of the Michelson-Morley experiments. Einstein's theories for the photoelectric effect extended the quantum theory which Max Planck had developed in his successful explanation of black body radiation.