After leaving the polytechnic in 1900 with teaching credentials, he gained Swiss citizenship in February 1901 and kept it for the rest of his life. The Swiss authorities deemed him unfit for military service, and schools offered him no post despite nearly two years of applications. At last, with Marcel Grossmann’s father helping, he secured work in Bern at the Swiss Patent Office as an assistant examiner, level III. It was not a glamorous beginning, but the office gave him steady hours, time to think, and a desk piled with inventions from a gravel sorter to an electric typewriter.

His employers made the post permanent in 1903, though they did not think he should be promoted until he had fully mastered machine technology. Yet the patent office may have been the very place where relativity began to take shape. He was judging devices that depended on signals, timing, and synchronised clocks, and his own thought experiments on light and motion drew from the same concerns. In 1902 he and friends in Bern formed the Olympia Academy, an ironic title for a small circle that read Henri Poincaré, Ernst Mach, and David Hume, with Marić sometimes listening in silence.

Einstein’s first published paper, on capillarity, appeared in Annalen der Physik in 1901. In 1902 and 1903 he wrote papers on thermodynamics, trying to interpret atomic phenomena statistically. In 1905 he completed his doctoral dissertation, A New Determination of Molecular Dimensions, dedicated to Marcel Grossmann and later approved by Alfred Kleiner at the University of Zurich. That same year, while still a patent clerk, he produced the four papers that would define modern physics. The year became his annus mirabilis, the miracle year, and even his contemporaries knew they were seeing a rare kind of intellect at work.

The first paper explained the photoelectric effect by treating light as quanta, an idea that would become central to quantum theory. The second explained Brownian motion and gave strong evidence that molecules exist. The third introduced special relativity, reconciling Maxwell’s equations with Newtonian mechanics by altering the rules of space and time. The fourth showed that mass and energy are equivalent, giving the world E = mc2, the most famous equation in physics. These papers were not isolated flashes. They were the outcome of years of reading, office work, and disciplined speculation.

Special relativity, received on 30 June 1905 and published that September, predicted that moving clocks run slow and moving bodies contract along the direction of motion. It also made the luminiferous ether unnecessary. Einstein framed the theory in kinematic terms, and in 1908 Hermann Minkowski recast it geometrically as spacetime, a formalism Einstein would later adopt. The mass-energy paper followed from the same work. Max Planck was among the first major physicists to accept it, though controversy lingered for years. What Einstein had done was to make time itself part of the machinery of physics.

At the same time, his papers on statistical mechanics were beginning to show how atoms behave in bulk. He treated thermodynamic fluctuations, critical opalescence, and the density variations of fluids at their critical point. In this work he linked the scattering of light to the atomistic constitution of matter, just as he had linked Brownian motion to the existence of molecules. The sky’s blueness, the milky whiteness of a critical fluid, and the jitter of tiny particles in water all became parts of one argument. Physics was not a bag of separate tricks, but a single coherent structure waiting to be seen.

In 1907 he made another crucial move with the equivalence principle. A person in a freely falling box cannot tell that a gravitational field exists, he argued, because free fall is itself a kind of inertial motion. The same year he published on quantum vibrations in a lattice, proposing a model in which each atom acted as an independent harmonic oscillator. It was a clear, if simplified, demonstration that quantum ideas could solve the specific heat problem. Peter Debye would later refine it, but Einstein had shown the route.

By 1908 he was no longer merely a clerk. He became a Privatdozent at the University of Bern, and in the same year the patent office promoted him to Technical Examiner Second Class. A year later, after a lecture on relativistic electrodynamics in Zurich impressed Alfred Kleiner, the University of Zurich lured him away from Bern with an associate professorship. In 1911 he became a full professor at the German Charles-Ferdinand University in Prague. That move required an Austrian citizenship he never quite completed, but it marked the rise of a man now recognised far beyond Switzerland.

Prague was productive. He produced eleven research papers there and attended the first Solvay Conference from 30 October to 3 November 1911, where the leading minds of physics gathered in one room. Then in July 1912 he returned to the ETH Zurich to take a chair in theoretical physics. He taught thermodynamics and analytical mechanics, while his research moved toward the molecular theory of heat, continuum mechanics, and a relativistic theory of gravitation. Marcel Grossmann, with his superior mathematical knowledge, became essential to that work. The friendship between the two men was no small thing; it was one of the great collaborations of modern science.

In the spring of 1913 Max Planck and Walther Nernst came to Zurich and tried to lure him to Berlin. They offered him membership of the Prussian Academy of Sciences, the directorship of the planned Kaiser Wilhelm Institute for Physics, and a chair at Humboldt University with salary but no teaching load. Berlin was attractive in itself, but also because Elsa Löwenthal, his cousin and then his girlfriend, was there. He joined the Academy on 24 July 1913, moved to Dahlem on 1 April 1914, and soon took up his university post. The move carried him back into German citizenship, and back into the centre of European science.

The First World War broke out in July 1914, and with it began his estrangement from the country of his birth. In October, when the Manifesto of the Ninety-Three defended German belligerence, Einstein refused to join it and instead signed the more pacific Manifesto to the Europeans. That did not stop him being elected president of the German Physical Society in 1916, nor did it halt his scientific ascent. In 1917 he became director of the Kaiser Wilhelm Institute for Physics, just as Planck and Nernst had promised, and that same year he wrote the paper that introduced spontaneous and stimulated emission, the basis of lasers and masers.

Meanwhile the struggle to complete general relativity was grinding forward. In 1913 he and Grossmann had produced the Entwurf, a draft theory, after Einstein became tangled in questions of gauge invariance and wrongly thought a fully covariant field theory impossible. But by the autumn of 1915 he had escaped the hole argument and returned to Riemannian geometry. In November he abandoned the Entwurf theory and completed the general theory of relativity, in which gravitation is no longer a force in the old sense but the curvature of spacetime itself. The equations were difficult, beautiful, and revolutionary.

General relativity extended his earlier work from motion to gravitation. It explained the precession of Mercury’s perihelion and predicted the bending of light by massive bodies. Einstein had first calculated that deflection in 1911 and refined it in 1913. In 1916 he also predicted gravitational waves, ripples in spacetime that carry energy outward from their source. They would not be directly confirmed until 2015, with LIGO’s detection announced in 2016, but the prediction itself was already part of the theory’s extraordinary reach. Einstein was teaching physics to the universe itself.

In 1917 he applied general relativity to the cosmos as a whole. The field equations implied a dynamic universe, but the evidence then available seemed to point to a static one, so he introduced the cosmological constant to hold the universe in equilibrium. The result was the Einstein static universe, a closed model that reflected his reading of Mach’s principle. That paper is often treated as the birth of modern theoretical cosmology. He later discarded the constant after Edwin Hubble’s 1929 discovery of galactic recession, though not before exploring new dynamic models in 1931 and 1932.

The road to public vindication came in 1919. On 29 May, during a total solar eclipse, Arthur Eddington observed starlight bent by the Sun’s gravity in a way consistent with Einstein’s calculations. On 7 November The Times in London announced, in its famous banner headline, Revolution in Science. Newtonian Ideas Overthrown. The effect on Einstein’s reputation was electric. He became perhaps the world’s first celebrity scientist, a man whose ideas had passed from papers and observatories into newspaper columns and the popular imagination.

In 1920 he was elected a Foreign Member of the Royal Netherlands Academy of Arts and Sciences, and in 1921 a Foreign Member of the Royal Society. The 1921 Nobel Prize in Physics was awarded to him in 1922 for services to theoretical physics and especially for the discovery of the law of the photoelectric effect. The committee delayed the award because the 1921 nominations were deemed insufficient under Alfred Nobel’s criteria. Even then, the citation carried a degree of caution, for not all physicists had accepted relativity, and the light-quantum idea would not be universally embraced until later.

By 1921 he was no longer merely a European figure. He arrived in New York on 2 April and was welcomed by Mayor John Francis Hylan. For three weeks he lectured and attended receptions, spoke at Columbia and Princeton, and visited the White House in Washington with representatives of the National Academy of Sciences. He returned through London as the guest of Viscount Haldane, met figures from British intellectual life, and lectured at King’s College. In July he wrote My First Impression of the U.S.A., praising the American character as joyous, positive, friendly, self-confident, and optimistic.

The following year he travelled east for six months, visiting Japan, Singapore, and Ceylon. In Tokyo he was greeted by thousands and met Emperor Yoshihito and his wife at the Imperial Palace. His private comments on Japan, China, and India were less generous than his public warmth, and that disjunction is part of his history too. He then spent twelve days in Mandatory Palestine, where Herbert Samuel received him with cannon salute and head-of-state ceremony. At one reception he told the crowd he was glad Jews were beginning to be recognised as a force in the world.

That same 1922 journey meant he missed the Stockholm Nobel ceremony. A German diplomat accepted the honour on his behalf at the banquet and praised him as both physicist and campaigner for peace. In April 1922, in Paris, he debated relativity with Henri Bergson, a confrontation that became a cause célèbre far beyond physics. In 1923 he visited Spain, received a diploma from King Alfonso XIII, and met Santiago Ramón y Cajal. By then the world was not simply reading Einstein’s papers. It was staging him as a cultural event.

From 1922 until 1932 he served on the Geneva-based International Committee on Intellectual Cooperation of the League of Nations, aside from a few months in 1923 and 1924. The committee was meant to encourage international cooperation among scientists, artists, scholars, and teachers. He was appointed as a German delegate, not a Swiss one, because of Catholic political manoeuvring by Oskar Halecki and Giuseppe Motta, which opened the way for Gonzague de Reynold. The board also included Hendrik Lorentz and Marie Curie. Einstein’s presence there suited his broader hopes for a world in which intellect crossed borders more easily than armies did.

In March and April 1925 he toured South America with Elsa, spending about a week each in Brazil and Uruguay, and a month in Argentina. The tour had been suggested by Jorge Duclout and Mauricio Nirenstein, supported by Argentine scholars such as Julio Rey Pastor, Jakob Laub, and Leopoldo Lugones, and financed mainly by the University of Buenos Aires and the Asociación Hebraica Argentina. The journey widened his fame still further, but it also kept him moving, always a little untethered from any one place.

By the late 1920s he had become a man increasingly visible in politics as well as science. In 1918 he signed the founding proclamation of the German Democratic Party. Later he drifted toward socialism and a critique of capitalism, making this case explicitly in essays such as Why Socialism? He wrote of world government as the only way to remove the greatest danger facing humanity, and the FBI opened a secret dossier on him in 1932. By the time of his death it had grown to 1,427 pages. His ideas and his person had both become objects of surveillance.

He was also a committed pacifist, though not an untroubled one. In 1929, at the Council of War Resisters in Zurich, he said that in the event of another war he would unconditionally refuse every direct or indirect war service and try to persuade his friends to do the same. He admired Mahatma Gandhi, and through Wilfrid Israel and the envoy V. A. Sundaram he exchanged letters with Gandhi in 1931, though they never met. Einstein called Gandhi a role model for generations to come. These were not abstract sentiments. They were part of his attempt to make morality match intellect.

At the same time, his personal life was becoming increasingly complicated. In 1912 he had begun a relationship with Elsa Löwenthal, his first cousin on his mother’s side and second cousin on his father’s. When Marić discovered his infidelity after moving to Berlin in April 1914, she returned to Zurich with Hans Albert and Eduard. Their divorce was granted on 14 February 1919, after five years apart. As part of the settlement, Einstein promised Marić the money from any Nobel Prize he might win, and when he did win it, he honoured that promise.

Einstein married Elsa in 1919. She remained loyal, and in 1933 she followed him when he emigrated to the United States. Yet the marriage did not end his entanglements. In 1923 he began a relationship with his secretary Betty Neumann, niece of Hans Mühsam. Later letters released by Hebrew University in 2006 named further women, including Margarete Lebach, Estella Katzenellenbogen, Toni Mendel, and Ethel Michanowski. After Elsa’s death in December 1936, he was briefly involved with Margarita Konenkova, whom some thought to be a Russian spy. The human story behind the legend is restless and uneven, not least because Einstein himself was.

His son Eduard suffered a severe mental breakdown around the age of twenty and was diagnosed with schizophrenia. He spent much of his life in his mother’s care or confined in an asylum, and after her death he was permanently committed to Burghölzli in Zurich. The cost of genius was not his alone. Hans Albert went on a different path, while Einstein himself kept returning to work, to travel, to correspondence, and to the intellectual life that often seemed to absorb him more completely than family life did.

The 1930s brought the decisive rupture. In December 1930 he began another stay in the United States, this time at Caltech. He arrived in New York, visited Chinatown, lunched with the editors of The New York Times, and attended Carmen at the Metropolitan Opera, where the audience cheered him. He received the keys to the city from Mayor Jimmy Walker, met Nicholas Murray Butler, and was called the ruling monarch of the mind. In California he met Robert A. Millikan, though their friendship was awkward because Millikan favoured patriotic militarism and Einstein remained a pronounced pacifist.

During that same California visit he befriended Upton Sinclair and Charlie Chaplin, both of them also known for pacifism. Carl Laemmle introduced him to Chaplin, and the two men struck up an immediate rapport. Chaplin invited Einstein and Elsa to dinner, then later to the premiere of City Lights in Hollywood. Chaplin said Einstein’s calm and gentle appearance hid a highly emotional temperament, and Einstein, in turn, found in Chaplin another public figure who understood the strange burden of fame. At the premiere they were cheered together, a physicist and a comic actor, each famous for being difficult to define.

Then 1933 changed everything. While he was again visiting the United States, Adolf Hitler came to power in Germany. Einstein knew he could not return. Gestapo raids on the Berlin apartment of his family began in February and March, and after the Reichstag passed the Enabling Act on 23 March he and Elsa learned that the way back was closed. Their cottage was raided, his personal sailboat confiscated, and on landing in Antwerp on 28 March he surrendered his German passport at the consulate. The Nazis sold the boat and turned the cottage into a Hitler Youth camp. The break was complete.

In April 1933 the new German government barred Jews from official posts, forcing thousands of Jewish scientists from universities while colleagues offered little protest. A month later the German Student Union burned Einstein’s works, and Joseph Goebbels declared Jewish intellectualism dead. One German magazine put him on a list of enemies with the words not yet hanged and a bounty on his head. Einstein wrote to Max Born in England that the brutality and cowardice had surprised him. In public he called the burnings a spontaneous emotional outburst by those who feared intellectual independence. The old homeland had become a place of threat.

For a time he had no permanent home. With help from the Academic Assistance Council, founded by William Beveridge to rescue persecuted academics, he rented a house in De Haan, Belgium. In July 1933 he spent six weeks in England at the invitation of Commander Oliver Locker-Lampson, who sheltered him in a wooden cabin on Roughton Heath in Norfolk, guarded by two bodyguards with shotguns. Locker-Lampson took him to meet Winston Churchill, Austen Chamberlain, and Lloyd George, and Einstein asked them to help bring Jewish scientists out of Germany. Churchill responded by sending Frederick Lindemann to find them places in British universities.

Einstein also wrote to İsmet İnönü in Turkey, asking that unemployed German-Jewish scientists be given work. That effort eventually helped more than 1,000 people. Locker-Lampson even tried to secure British citizenship for him, while Einstein spoke publicly about the crisis in Europe and about Jewish citizenship in Palestine. The effort failed, but another door opened. He accepted the Institute for Advanced Study in Princeton, New Jersey, as resident scholar. On 3 October 1933, at the Royal Albert Hall, he spoke on academic freedom to a packed audience and was wildly cheered. Four days later he returned to the United States for good.

At Princeton he joined the Institute for Advanced Study, founded partly as a refuge for scholars fleeing Nazi Germany. He was one of the first four selected, alongside John von Neumann, Kurt Gödel, and Hermann Weyl. He and Gödel became close friends, walking together and discussing logic and physics. He lived in Princeton from 1935 onward at what became the Albert Einstein House, later a National Historic Landmark. In 1935 he decided to remain in the United States permanently and apply for citizenship. Elsa died in December 1936, and the move into American life became final.

He became an American citizen in 1940. In Princeton he praised the meritocratic spirit of the United States, the right of people to think and speak freely, and the absence of some of the rigid social barriers he had known in Europe. Yet he also found America troubled by racism. He joined the NAACP, corresponded with W. E. B. Du Bois, and was prepared to testify for him in 1951 before the judge dropped the case. In 1946 he visited Lincoln University in Pennsylvania, received an honorary degree, and spoke against American racism, saying he did not intend to be quiet about it.

His concern for black Americans was personal as well as political. He is said to have paid tuition for a black student, and when Marian Anderson was refused a room at the Nassau Inn in Princeton in 1937, he invited her to stay at his house on Main Street. She returned whenever she sang in Princeton, last visiting only two months before his death. Einstein knew what it was to be treated as an outsider, and in America he used his fame to resist that logic where he could.

The war years brought the gravest moral dilemma of his life. In July 1939 Leó Szilárd and Eugene Wigner visited him to explain the possibility of atomic bombs and the danger that German scientists might build one first. Einstein, who had not considered it, agreed to lend his name to a letter to Franklin D. Roosevelt urging American nuclear research. The letter is often described as a key stimulus to the United States programme that led to the Manhattan Project. He also used his contacts with the Belgian royal family to help get the warning to the Oval Office.

For a pacifist, the decision was painful. He later said that war was a disease and that he had made one great mistake in signing the Roosevelt letter, though he added that the German threat gave it justification. In 1955, the year of his death, he joined Bertrand Russell and others in a manifesto warning of the danger of nuclear weapons. The contradiction remained central to his public image: the man who had urged caution about violence had also helped start the race that made destruction industrial.

Yet his political life did not end with wartime urgency. He was still thinking about world government, still believing that national states were too dangerous when left unchecked. He saw socialism as a remedy for human suffering, and capitalism as morally limited. He thought in international terms, perhaps because he had lived as a Swiss citizen, a German again, an American later, and, above all, as a Jew moving through the storms of the twentieth century. The FBI file grew even as his ideas grew broader.

His religious views were equally distinctive. He admired Spinoza’s impersonal God, rejected a personal deity who meddled in human affairs, and said he was not an atheist but rather agnostic, even a deeply religious nonbeliever. He believed science could produce a special kind of religious feeling by revealing the spirit in the laws of the universe. He served on humanist and Ethical Culture boards in Britain and the United States, and for the seventy-fifth anniversary of the New York Society for Ethical Culture he praised ethical culture as embodying what was most valuable in religious idealism.

In January 1954 he wrote to Eric Gutkind in language that has become famous for its bluntness. God, he said, was for him no more than the expression and product of human weaknesses, and the Bible a collection of honourable but still primitive legends. He called the Jewish religion childish superstition, though he also said he felt a deep affinity with the Jewish people. A year earlier, in 1953 and again in 1954, he had written about vegetarianism, which he embraced in the final part of his life. In March 1954 he said he was living without fats, meat, or fish, and feeling well.

Music remained one of the few constant delights. His mother had wanted him to learn violin partly to help him assimilate, and by five he had begun, though he disliked it at first. At thirteen, after discovering Mozart’s violin sonatas, he fell in love with music and taught himself without systematic practice. He said love was a better teacher than duty. At seventeen, while in Aarau, an examiner heard him play Beethoven and remarked on his great insight. Later he played chamber music in Bern, Zurich, and Berlin, with professionals such as Kurt Appelbaum and with Max Planck and his son.

He preferred Mozart, calling the music so pure that it seemed ever-present in the universe, but he preferred Bach to Beethoven, saying give me Bach, rather, and then more Bach. In 1931, while at Caltech, he played with the Zoellner Quartet in Los Angeles. Near the end of his life the Juilliard Quartet visited him in Princeton, and they were impressed by his coordination and intonation. Music was never a career, but it was a language in which he seemed at home, and perhaps one reason the world found him human rather than merely abstract.

Scientifically, the later years were mixed with brilliance and frustration. He made important contributions to statistical mechanics and quantum theory, especially the idea that light consists of particles now called photons. With Satyendra Nath Bose he laid the groundwork for Bose-Einstein statistics, later confirmed experimentally in 1995 by Eric Cornell and Carl Wieman. He also proposed stimulated emission in 1917, which would underpin lasers and masers, and he worked on the Einstein refrigerator with Leó Szilárd, patented in 1930. Yet his deepest late ambitions did not come good.

Those ambitions were twofold. First, he resisted the probabilistic core of quantum mechanics, objecting that God does not play dice. He accepted its accuracy but not its completeness. The Bohr-Einstein debates with Niels Bohr became famous because they were really arguments about what science can know. In 1935 he published the EPR paper with Boris Podolsky and Nathan Rosen, arguing that quantum mechanics left reality incomplete. John Stewart Bell later showed how the problem could be sharpened, but during Einstein’s life the argument became one of the defining philosophical disputes of twentieth-century physics.

Second, he pursued a unified field theory, trying to join gravitation and electromagnetism into a single geometric structure. In 1950 he wrote about it in Scientific American, but the attempt never succeeded, partly because it did not account for the strong and weak nuclear forces, which were not then understood. He also explored wormholes with Nathan Rosen in 1935, and continued to work on force, superconductivity, and other abandoned lines. By then he had become increasingly isolated from mainstream physics, not because he had ceased to matter, but because the field had moved in directions he could not accept.

Even so, his influence kept widening. In 1926 he and Szilárd patented the Einstein refrigerator, a heat-driven absorption refrigerator with no moving parts. He also invented an electromagnetic pump and a sound reproduction device. He published more than 300 scientific papers and 150 non-scientific ones, and his archives eventually filled over 30,000 documents. In 1979 a memorial was unveiled in Washington, D.C., showing him with three equations in hand. Mount Einstein in Alaska was named in 1955, and another in New Zealand in 1970. The honours gathered long after the man himself had gone.

He also left institutions behind. In his final four years he helped establish the Albert Einstein College of Medicine in New York City. He bequeathed his personal archives, library, and intellectual assets to the Hebrew University of Jerusalem, an institution he had helped promote from its beginnings in the 1920s when Chaim Weizmann asked him to assist with fundraising. He had suggested institutes for agriculture, chemistry, microbiology, and Oriental studies, and though he opposed a separate Jewish state at first, he later accepted that Israel existed and had to be supported.

In 1952, after Weizmann’s death, David Ben-Gurion offered him the largely ceremonial presidency of Israel. The ambassador Abba Eban presented the offer as a mark of the deepest respect the Jewish people could pay one of its sons. Einstein was deeply moved, but saddened and ashamed that he could not accept. Ben-Gurion reportedly asked what to do if he said yes. The answer never came, because Einstein declined. The office was not for him, but the gesture revealed how large his symbolic stature had become in Jewish and world affairs alike.

The world kept naming things after him. Einsteinium, a synthetic element, was named in 1955, a few months after his death. Many other honours followed, and in 1999 Time named him Person of the Century. In the same year, physicists’ surveys placed him among the greatest ever, often second only to Newton. The International Union of Pure and Applied Physics declared 2005 the World Year of Physics, Einstein Year, marking a hundred years since his miracle year. The numbers alone tell a story of endurance.

But the truest measure of his life may lie in its arc. Born in Ulm in 1879, raised in Munich, educated in Aarau and Zurich, clerk in Bern, professor in Prague, Zurich, and Berlin, exile in Belgium and England, refugee in Princeton, he crossed not just borders but eras. He helped turn physics from the study of forces and particles into the study of spacetime, quanta, and cosmology. He also moved through pacifism, Zionism, socialism, humanism, music, and mourning. Few lives touched so many fields and left so many marks.

When he died in Princeton on 18 April 1955, the papers on his desk still connected to Israel, the brain was already on its way into medical history, and the theories were already part of the modern world. He had discovered the photoelectric law, explained Brownian motion, given us special and general relativity, helped shape quantum physics, and spent his last decades chasing a unified whole that eluded him. That final irony is fitting: the man who made the universe less mysterious ended his own life still trying to make it one.

Albert Einstein

From Ulm to Princeton, the life that remade physics