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Albert Einstein (German: ˈalbɐt ˈaɪ̯nʃtaɪ̯n ; English: /ˈælbərt ˈaɪnstaɪn/; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist. He is best known for his theory of relativity and specifically mass–energy equivalence, expressed by the equation E = mc2. Einstein received the 1921 Nobel Prize in Physics “for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect.”
Einstein’s many contributions to physics include:
- Special theory of relativity, which reconciled mechanics with electromagnetism
- General theory of relativity, a new theory of gravitation which added the principle of equivalence to the principle of relativity
- Founding of relativistic cosmology with a cosmological constant
- The first post-Newtonian expansions for the perihelion advance of planet Mercury and frame-dragging
- The deflection of light by gravity and gravitational lensing
- An explanation for capillary action
- The first fluctuation dissipation theorem which explained the Brownian movement of molecules
- The photon theory and wave-particle duality from the thermodynamic properties of light
- The quantum theory of atomic motion in solids
- Zero-point energy
- The semiclassical version of the Schrodinger equation
- Relations for atomic transition probabilities which predicted stimulated emission
- The quantum theory of a monatomic gas which predicted Bose-Einstein condensation
- The EPR paradox
- A program for a unified field theory by the geometrization of physics.
Einstein published more than 300 scientific works and more than 150 non-scientific works. In 1999 Time magazine named him the “Person of the Century“, and in the words of Einstein biographer Don Howard, “to the scientifically literate and the public at large, Einstein is synonymous with genius.”
Following graduation, Einstein could not find a teaching post. After almost two years of searching, a former classmate’s father helped him get a job in Berne, at the Federal Office for Intellectual Property, the patent office, as an assistant examiner. His responsibility was evaluating patent applications for electromagnetic devices. In 1903, Einstein’s position at the Swiss Patent Office was made permanent, although he was passed over for promotion until he “fully mastered machine technology”.
With friends he met in Berne, Einstein formed a weekly discussion club on science and philosophy, jokingly named “The Olympia Academy“. Their readings included Poincaré, Mach, and Hume, who influenced Einstein’s scientific and philosophical outlook.
During this period Einstein had almost no personal contact with the physics community. Much of his work at the patent office related to questions about transmission of electric signals and electrical-mechanical synchronization of time: two technical problems that show up conspicuously in the thought experiments that eventually led Einstein to his radical conclusions about the nature of light and the fundamental connection between space and time.
Marriage and family life
Einstein married Mileva on 6 January 1903, although his mother had objected to the match because she had a prejudice against Serbs and thought Marić “too old” and “physically defective.”  Their relationship was for a time a personal and intellectual partnership. In a letter to her, Einstein called Marić “a creature who is my equal and who is as strong and independent as I am.” There has been occasional debate about whether Marić influenced Einstein’s work, however, the overwhelming consensus amongst academic historians of science is that she did not. On 14 May 1904, Albert and Mileva’s first son, Hans Albert Einstein, was born in Berne, Switzerland. Their second son, Eduard, was born in Zurich on 28 July 1910.
Albert and Marić divorced on 14 February 1919, having lived apart for five years. On 2 June of that year, Einstein married Elsa Löwenthal (née Einstein), who had nursed him through an illness. Elsa was Albert’s first cousin maternally and his second cousin paternally. Together the Einsteins raised Margot and Ilse, Elsa’s daughters from her first marriage. Their union produced no children.
Annus Mirabilis and special relativity
In 1905, while he was working in the patent office, Einstein had four papers published in the Annalen der Physik, the leading German physics journal. These are the papers that history has come to call the Annus Mirabilis Papers:
- His paper on the particulate nature of light put forward the idea that certain experimental results, notably the photoelectric effect, could be simply understood from the postulate that light interacts with matter as discrete “packets” (quanta) of energy, an idea that had been introduced by Max Planck in 1900 as a purely mathematical manipulation, and which seemed to contradict contemporary wave theories of light (Einstein 1905a).
- His paper on Brownian motion explained the random movement of very small objects as direct evidence of molecular action, thus supporting the atomic theory. (Einstein 1905c)
- His paper on the electrodynamics of moving bodies introduced the radical theory of special relativity, which showed that the observed independence of the speed of light on the observer’s state of motion required fundamental changes to the notion of simultaneity. Consequences of this include the time-space frame of a moving body slowing down and contracting (in the direction of motion) relative to the frame of the observer. This paper also argued that the idea of a luminiferous aether—one of the leading theoretical entities in physics at the time—was superfluous. (Einstein 1905d)
- In his paper on mass–energy equivalence (previously considered to be distinct concepts), Einstein deduced from his equations of special relativity what has been called the twentieth century’s most well known equation: E = mc2. This suggests that tiny amounts of mass could be converted into huge amounts of energy and presaged the development of nuclear power. (Einstein 1905e)
All four papers are today recognized as tremendous achievements—and hence 1905 is known as Einstein’s “Wonderful Year“. At the time, however, they were not noticed by most physicists as being important, and many of those who did notice them rejected them outright. Some of this work—such as the theory of light quanta—remained controversial for years.
At the age of 26, having studied under Alfred Kleiner, Professor of Experimental Physics, Einstein was awarded a PhD by the University of Zurich. His dissertation was entitled A New Determination of Molecular Dimensions. (Einstein 1905b)
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