In the seventeenth century, the simplicity and elegance with which Isaac Newton had managed to explain the laws governing the movement of bodies and the stars, unifying terrestrial and celestial physics, so dazzled his contemporaries that he came to be considered completed the mechanics. At the end of the 19th century, however, the relevance of some phenomena that classical physics could not explain was already unavoidable. It was up to Albert Einstein to overcome these shortcomings with the creation of a new paradigm: the theory of relativity, the starting point of modern physics. Albert Einstein in 1947. As an explanatory model completely removed from common sense, relativity is counted among those advances that, at the dawn of the 20th century, would lead to a divorce between ordinary people and an increasingly specialized and unintelligible science. However, even in life of the physical or posthumously, even the most surprising and incomprehensible aspects of relativity would end up being confirmed. It should not be surprising, then, that Albert Einstein is one of the most celebrated and admired characters in the history of science: knowing that there are so many ideas barely conceivable (for example, that the mass of a body increases with speed) does not stop More choice than to surrender to his genius. A bad student. Albert Einstein was born in the Bavarian city of Ulm on March 14, 1879. He was the firstborn son of Hermann Einstein and Pauline Koch, Jews both, whose families came from Swabia. The following year they moved to Munich, where the father was established, along with his brother Jakob, as a merchant in the electrotechnical news of the time. Little Albert was a quiet and self-absorbed child, and had a slow intellectual development. Einstein himself attributed to that slowness the fact of having been the only person to elaborate a theory like that of relativity: "a normal adult does not worry about the problems posed by space and time, since he considers that everything there is that know about it already knows him from his early childhood. I, on the other hand, have had such a slow development that I have not begun to ask questions about space and time until I have been older ». In 1894, economic difficulties caused the family (increased since 1881 with the birth of a daughter, Maya) to move to Milan; Einstein stayed in Munich to finish high school, meeting with his parents the following year. In the fall of 1896 he began his higher studies at the Eidgenossische Technische Hochschule in Zurich, where he was a student of the mathematician Hermann Minkowski, who later generalized the four-dimensional formalism introduced by the theories of his former student. Einstein with Elsa, his second wife. On June 23, 1902, Albert Einstein began to serve in the Confederal Intellectual Property Office of Bern, where he worked until 1909. In 1903 he married Mileva Maric, a former student companion in Zurich, with whom he had two children. : Hans Albert and Eduard, born respectively in 1904 and in 1910. In 1919 they divorced, and Einstein married again with his cousin Elsa. Relativity. During 1905, he published five papers in the Annalen der Physik: the first of them earned him the degree of doctor by the University of Zurich, and the remaining four would end up imposing a radical change in the image that science offers the universe. Of these four, the first provided a theoretical explanation in statistical terms of Brownian motion (so named after its discoverer, Robert Brown), and the second gave an interpretation of the photoelectric effect based on the hypothesis that light is integrated by how many individual, later called photons. The two remaining works laid the foundations of the restricted theory of relativity, establishing the equivalence between the energy E of a certain amount of matter and its mass m in terms of the famous equation E = mc², where c is the speed of light , which is supposed constant. Einstein's effort placed him immediately among the most eminent of European physicists, but the public recognition of the true extent of his theories was slow to arrive; The Nobel Prize for Physics, which he received in 1921, was granted exclusively "for his work on the Brownian movement and its interpretation of the photoelectric effect." In 1909 he began his career as a university teacher in Zurich, then moved to Prague and returned to Zurich in 1912 to become a professor at the Polytechnic, where he had completed his studies.