Einstein

The life of Albert Einstein

Timeline 1879Born on 14 March in Ulm, in southern Germany. The family soon moves to Munich. 1891At 12, receives a book of Euclidean geometry, which he would call the “holy little book”. 1895Fails the entrance exam of the Zurich Polytechnic, despite high marks in mathematics and physics. 1900Graduates in Zurich. Spends two years without a steady job. 1902Starts work at the patent office in Bern, as a “technical expert, third class”. 1905The miraculous year: four papers that change physics and a doctoral thesis. 1909Leaves the patent office and becomes a professor in Zurich. 1914Moves to Berlin, as a member of the Prussian Academy of Sciences. 1915Presents the equations of general relativity. 1919The eclipse of 29 May, observed in Sobral and on the island of Príncipe, confirms the theory. Einstein becomes world-famous. 1922His Nobel Prize in Physics for 1921 is announced, for the photoelectric effect. 1925Visits Rio de Janeiro, from 4 to 12 May. 1933With the Nazis in power, leaves Germany for good. Settles in Princeton, in the United States. 1939Signs a letter to President Roosevelt about the possibility of an atomic bomb. 1955Dies on 18 April in Princeton. ◀ Previous Follow the journey Next ▶ 1879 UlmBorn on 14 March. The family soon moves away. 1880–1894 MunichHe receives the “holy little book” of geometry and hates his school, where everything is learned by heart. 1894–1895 ItalyAt 15 he leaves school and follows his family, which has moved to Italy. 1895–1896 AarauHaving failed the Zurich exam, he finishes secondary school at a freer Swiss school. 1896–1902 ZurichHe studies at the Polytechnic and graduates in 1900. He spends two years without a steady job. 1902–1909 BernTechnical expert third class at the patent office. In 1905, the miracle year, he writes four papers that change physics. 1911–1912 PragueProfessor at the University of Prague, between two periods in Zurich. 1914–1932 BerlinA member of the Prussian Academy. He presents general relativity (1915) and becomes famous after the 1919 eclipse. 1925 Rio de JaneiroHe spends eight days in Rio, from 4 to 12 May, and is enchanted by the Botanical Garden. 1933–1955 PrincetonWith the Nazis in power, he leaves Germany. He works at the Institute for Advanced Study until his death in 1955. Enable JavaScript to see the map. The stages are listed below. From Ulm to Princeton, with a stop in Rio de Janeiro. Map: © OpenStreetMap contributors

October 14, 2026 Read

The photoelectric effect: light comes in packets

It deals with radiation and the energy properties of light and is very revolutionary. — Albert Einstein, letter to Conrad Habicht (May 1905) In May 1905 Einstein wrote to his friend Conrad Habicht announcing four papers. Of the four, he called only one revolutionary, and it was not relativity: it was the paper on light, sent to the Annalen der Physik in March. It was for this paper that Einstein won the Nobel Prize.

October 14, 2026 Read

Brownian motion: counting the atoms

If the motion discussed here can actually be observed, then classical thermodynamics can no longer be looked upon as strictly valid for spaces distinguishable under the microscope, and an exact determination of actual atomic dimensions is then possible. — Albert Einstein, Annalen der Physik (May 1905) In 1905 many physicists and chemists still doubted that atoms existed. Chemistry worked very well with the hypothesis, but nobody had seen an atom, and important scientists, such as the Austrian physicist Ernst Mach and the German chemist Wilhelm Ostwald, thought atoms were just a convenient way of doing calculations. Einstein found a way to see them, or almost: through their effect on things big enough to show up under a microscope.

October 14, 2026 Read

Special relativity: a clock made of light

If I pursue a beam of light with the velocity c, the velocity of light in a vacuum, I should observe such a beam of light as an electromagnetic field at rest though spatially oscillating. There seems to be no such thing, however. — Albert Einstein, Autobiographical Notes (1949) At 16, at school in Aarau, Einstein asked himself a question: what would I see if I ran alongside a beam of light, at the same speed? According to Newton’s physics, the light would seem to stand still, like a car beside ours on the motorway. But Maxwell’s equations do not allow light at rest: for them, light always travels at $c\approx300{,}000$ km/s. Someone was wrong. Einstein took ten years to find out who.

October 14, 2026 Read

E = mc²: the energy hidden in mass

One more consequence of the paper on electrodynamics has occurred to me. The principle of relativity, together with Maxwell’s equations, requires that mass be a direct measure of the energy contained in a body. The idea is amusing and enticing; but for all I know, the Lord may be laughing over the whole thing and leading me around by the nose. — Albert Einstein, letter to Conrad Habicht (summer 1905) In September 1905, three months after the relativity paper, Einstein sent the Annalen der Physik a supplement of just three pages, with a title in the form of a question: “Does the inertia of a body depend upon its energy content?”. The answer was yes, and the conclusion, written in words and with other letters, is the most famous formula in physics:

October 14, 2026 Read

General relativity: from the lift to the Sobral eclipse

I was sitting in a chair in the patent office in Bern when all of a sudden a thought occurred to me: if a person falls freely, he will not feel his own weight. I was startled. This simple thought made a deep impression on me. It impelled me towards a theory of gravitation. — Albert Einstein, on an idea of 1907 The relativity of 1905 had a flaw: it did not include gravity. Newton’s law says the Sun pulls the Earth instantly, across 150 million kilometres, and relativity says nothing travels faster than light. Einstein spent eight years trying to fix this. His starting point was what he called “the happiest thought of my life”.

October 14, 2026 Read

The legacy of Albert Einstein

Imagination is more important than knowledge. Knowledge is limited; imagination encircles the world. — Albert Einstein, interview in the Saturday Evening Post (1929) Einstein is the only scientist whose face everyone recognises. But his legacy is not on the posters: it is in devices we use without thinking and in questions physicists are still trying to answer. Several of his predictions were only confirmed decades after his death. The laser In 1917, studying how matter absorbs and emits light, Einstein realised that, besides absorbing and emitting photons spontaneously, an excited atom can be stimulated by a photon to emit another, identical one, in the same direction. It was a theoretical observation. Forty years later it became the laser, the acronym for “light amplification by stimulated emission of radiation”. Barcode readers, optical fibres, eye surgery and lecture pointers are all applications of stimulated emission.

October 14, 2026 Read

Image credits

Historical images All come from Wikimedia Commons. We use the thumbnails provided by Commons; the largest were reduced to 1,200 pixels wide, with no other editing. Portrait of Einstein in 1921, possibly by Herman Mishkin, used by the Nobel Foundation: source page · public domain. Einstein around 1904, in Bern, photo by Lucien Chavan: source page · public domain. Einstein at the National Museum, Rio de Janeiro, 7 May 1925, unknown author: source page · public domain. Einstein in the Botanical Garden of Rio de Janeiro, May 1925, unknown author: source page · public domain. The instruments of the expedition in Sobral, 1919, photo by Charles Davidson: source page · public domain. Plate of the 1919 eclipse, from the report by Dyson, Eddington and Davidson: source page · public domain. Blog figures The cover, the diagram of the light clock and the 2,000-step random walk are original illustrations, with versions in each of the site’s languages. The light-clock diagram was redrawn from a figure in this site’s old course on the theory of relativity, which is also the source of the examples of the astronaut and of the cosmic-ray particles. The random walk was generated by computer, with randomly drawn directions.

October 14, 2026 Read