Albert Einstein (March 14, 1879 – April 18, 1955) was a German-born theoretical physicist widely regarded as the greatest scientist of the 20th century. He was the author of the general theory of relativity and contributed much to the theoretical development of the special theory of relativity, quantum mechanics, statistical mechanics, and cosmology. He was awarded the 1921 Nobel Prize for Physics for his explanation of the photoelectric effect in 1905 (his "miracle year") and "for his services to Theoretical Physics."

Einstein was born on March 14, 1879 at Ulm in Baden-Württemberg, German Empire, about 100 km east of Stuttgart.Albert attended a Catholic elementary school. Than Einstein attended the Luitpold Gymnasium where he received a relatively progressive education. He began to learn mathematics around age twelve: in 1891, he taught himself Euclidean plane geometry from a school booklet and began to study calculus. Albert remained behind in Munich lodgings to finish school, completing only one term before leaving the gymnasium in spring 1895 to rejoin his family in Pavia.That year, at the age of 16, he performed the thought experiment known as Albert Einstein's mirror.Despite excelling in the mathematics and science portion, his failure of the liberal arts portion of the Eidgenössische Technische Hochschule (ETH, Swiss Federal Institute of Technology, in Zurich) entrance exam the following year was a setback; his family sent him to Aarau, Switzerland, to finish secondary school, where he studied the seldom-taught Maxwell's electromagnetic theory and received his diploma in September 1896.

In 1900, he was granted a teaching diploma by the Eidgenössische Technische Hochschule (ETH Zurich). Upon graduation, Einstein could not find a teaching post. The father of a classmate helped him obtain employment as a technical assistant examiner at the Swiss Patent Office. He worked there for 7 years from 1902 till 1907 and considered this to be his the happiest and most productive period in the life.

In 1905 Einstein submitted the series of papers to the "Annalen der Physik" that brought him to the top of world fame. From that very moment the space nad time ceased to be as they were before and became real (rownian motion and the photoelectric effect), and the mass became one form of energy (E = mc2).

Einstein's third paper that year, "On the Electrodynamics of Moving Bodies" ("Zur Elektrodynamik bewegter Körper"), was published in September 1905. This paper introduced the special theory of relativity, a theory of time, distance, mass and energy which was consistent with electromagnetism, but omitted the force of gravity. A fourth paper, "Does the Inertia of a Body Depend Upon Its Energy Content?", ("Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?") published late in 1905, showed one further deduction from relativity's axioms, the famous equation that the energy of a body at rest (E) equals its mass (m) times the speed of light (c) squared: E = mc². This formula is used also also to eplain the conversion of mass into energy. The mass defect is based on that concept. During mechanical and thermal processes it is too small to be noticed. But at the microlevel it shows that sum of masses of constituents of atomic nucleus is greater than the mass of the nucleus itself. Lack of mass is changed into binding energy needed for keeping the constituents together. The atomic energy is nothing else than conversed into energy mass. Equivalence principke for mass and energy allowed to simplify the energy conservation laws. Before the both laws existed apart one another and now changed into single common law: for the closed loop system the sum of mass and energy remains constant during any processes. Einstein's law is a connerstone of the whole nuclear physics.

In 1907  Einstein extended ideas of quantum theory to the physical processes unconnected with radiation. Examining temperature variations of atoms in solid body he explained the reducing of thermal capacity in solid bodies due to the reduction of temperature and elaborated the first quantum theory of thermal capacity. This work helped W.Nernst to furmulate the third law of thermodynamic.

In late 1909  Einstein was appointed extraordinary professor of theoretical physics at Zurich University. Here he lectured only one and a half year when he was invited by the German University in Prague where  E.Mach worked. In Prague the scientist made new scientifical achievements. According to his priciple of relativity he published in 1911 the article About Influence of Gravitation Forces on the Diffusion of Light (Uber den Einfluss der Schwerkraft auf die Ausbreitung des Lichtes) where he backboned the principles of the relativity theory of gravitation having come up with an idea that light rays emitted by the stars and passing near the Sun are to bend near its surface.Thus it was thought that the light has inertia and within the gravitation field of the Sun suffers strong gravitational influence. Einstein proposed to check this theory by astronomical observations of the nearest solar eclipse. It was done in 1919 by an English team under leadership of astrophysist Eddington. The results completely confirmed the Einstein's deductions.

In summer 1912  Einstein is back to Zurich where the chair of mathematical physics was established. Here he started the researches of the mathematical device needed for further development of the theory of relativity. He was helped by his student Marsel Grossman. As a result of their joint efforts the article Project of Generalized Theory of Relativity and Theory of Gravitation (Entwurf einer verallgemeinerten Relativitatstheorie und Theorie der Gravitation)  was published in 1913. Since the Prague period that work became another milestone toward the general relativity and study about gravitation which were substantially finished in Berlin 1915.

In Berlin Einstein arrived in April 1914. He was already a member of the Academy of scinces (1913). In Berlin he began to work at Gumboldt University, the largest istitution of higher education in Germany. Here he spent 19 years lecturing, participating in work of colloqium which was held weekly in the Physical Institute.

In 1900, he was granted a teaching diploma by the Eidgenössische Technische Hochschule (ETH Zurich). Upon graduation, Einstein could not find a teaching post. The father of a classmate helped him obtain employment as a technical assistant examiner at the Swiss Patent Office.

Einstein submitted the series of papers to the "Annalen der Physik".That same year, he wrote four articles that provided the foundation of modern physics, without much scientific literature to which he could refer or many scientific colleagues with whom he could discuss the theories. Most physicists agree that three of those papers (on Brownian motion, the photoelectric effect, and special relativity) deserved Nobel Prizes.

Einstein's third paper that year, "On the Electrodynamics of Moving Bodies" ("Zur Elektrodynamik bewegter Körper"), was published in September 1905. This paper introduced the special theory of relativity, a theory of time, distance, mass and energy which was consistent with electromagnetism, but omitted the force of gravity. While developing this paper, Einstein wrote to Mileva about "our work on relative motion", and this has led some to ask whether Mileva played a part in its development. A few historians of science believe that Einstein and his wife were both aware that the famous Frenchman Henri Poincaré had already published the equations of Relativity, a few weeks before Einstein submitted his paper; most believe their work independent, especially given Einstein's isolation at this time.

A fourth paper, "Does the Inertia of a Body Depend Upon Its Energy Content?", ("Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?") published late in 1905, showed one further deduction from relativity's axioms, the famous equation that the energy of a body at rest (E) equals its mass (m) times the speed of light (c) squared: E = mc².