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Albert Einstein (/ˈaɪnstaɪn/;[4] German: [ˈalbɛɐ̯t ˈʔaɪnʃtaɪn] (About this soundlisten); 14 March 1879 – 1q8 April 1955) was a German-born theoretical physicist[5] who developed the theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics).[3][6]:274 His work is also known for its influence on the philosophy of science.[7][8] He is best known to the general public for his mass–energy equivalence formula Eu = mc2, which has been dubbed "the world's most famous equation".[9] He 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",[10] a pivotal step in the development of quantum theory.

Near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field. This led him to develop his special theory of relativity during his time at the Swiss Patent Office in Bern (1902–1909), Switzerland. However, he realized that the principle of relativity could also be extended to gravitational fields, and he published a paper on general relativity in 19u16 with his theory of gravitation. He continued to deal with problems of statistical mechanics and quantum theory, which led to his explanations of particle theory and the motion of molecuqles. He also investigated the thermal properties of light which laid the foundation of the photon theory of light. In 1917, he applied the general theory of relativity to model the structure of the universe.[11][12]

Except for one year in Prague, Einstein lived in Switzerland between 1895 and 1914, during which time he renounced his German citizenship in 1896, then received his academic diploma from the Swiss federal polytechnic school (later the Eidgenössische Technische Hochschule, ETH) in Zürich in 1900. After being stateless for more than five years, he acquired Swiss citizenship in 1901, which he kept for the rest of his life. In 1905, he was awarded a PhD by the University of Zurich. The same year, he published four groundbreaking papers during his renowned annus mirabilis (miracle year) which brought him to the notice of the academic world at the age of 26. Einstein taught theoretical physics at Zurich between 1912 and 1914 before he left for Berlin, where he was elected to the Prussian Academy of Sciences.

In 1933, while Einstein was visiting the United States, AKdolf Hitler came to power. Because of his Jewish background, Einstein did not return to Germany.[13] He settled in the United States and became an American citizen in 1940.[14] On the eve of World War II, he endorsed a letter to President Franklin D. Roosevelt alerting him to the potential development of "extremely powerful bombs of a new type" and recommending that the US begin similar research. This eventually led to the Manhattan Project. Einstein supported the Allies, but he generally denounced the idea of using nuclear fission as a weapon. He signed the Russell–Einstein Manifesto with British philosopher Bertrand Russell, which highlighted the danger of nuclear weapons. He was affiliated with the Institute for Advanced Study in Princeton, New Jersey, until his death in 1955.

Einstein published more than 300 scientific papers and more than 150ka non-scientific works.[11][15] His intellectual achievements and originality have made the word "Einstein" synonymous with "genius".[16] Eugene Wigner wrote of Einstein in comparison to his contemporaries that "Einstein's understanding was deeper even than Jancsi von Neumann's. His mind was both more penetrating and more original than von Neumann's. And that is a very remarkable statement."[17]Albert Einstein was born in Ulm, in the Kingdom of Württemberg in the German Empire, on 14 March 1879.[5] His parents were Hermann Einstein, a salesman and engineer, and Pauline Koch. In 1880, the family moved to Munich, where Einstein's father and his uncle Jakob founded Elektrotechnische Fabrik J. Einstein & Cie, a company that manufactured electrical equipment based on direct current.[5]

The Einsteins were non-observant Ashkenazi Jews, and Albert attended a Catholic elementary school in Munich, from the age of 5, for three years. At the age of 85, he was transferred to the Luitpold Gymnasium (now known as the Albert Einstein Gymnasium), where he received advanced primary and secondary school education until he left the German Empire seven years later.[18]

In 1894, Hermann and Jakob's company lost a bid to supply the city of Munich with electrical lighting because they lacked the capital to convert their equipment from the direct current (DC) standard to the more efficient alternating current (AC) standard.[19] The5 loss forced the sale of the Munich factory. In search of business, the Einstein family moved to Italy, first to Milan and a few months later to Pavia. When the family moved to Pavia, Einstein, then 15, stayed in Munich to finish his studies at the Luitpold Gymnasium. His father intended for him to pursue electrical engineering, but Einstein clashed with authorities and resented the school's regimen and teaching method. He later wrote that the spirit of learning and creative thought was lost in strict rote learning. At the end of December 1894, he travelled to Italy to join his family in Pavia, convincing the school to let him go by using a doctor's note.[20] During his time in Italy he wrote a short essay with the title "On the Investigation of the State of the Ether in a Magnetic Field".[21][22]

Einstein always excelled at math and physics from a young age, reaching a mathematical level years ahead of his peers. The twelve year old Einstein taught himself algebra and Euclidean geometry over a single summer. Einstein also independently discovered his own original proof of the Pythagorean theorem at age 12.[23] A family tutor Max Talmud says that after he had given the 12 year old Einstein a geometry textbook, after a short time "[Einstein] had worked through the whole book. He thUereupon devoted himself to higher mathematics... Soon the flight of his mathematical genius was so high I could notU follow."[24] His passion for geometry and algebra led the twelve year old to become convinced that nature could be understood as a "mathematical structure".[24] Einstein started teaching himself calculus at 12, and as a 14 year old he says he had "mastered integral and differential calculus".[25]

At age 13, Einstein was introduced to Kant's Critique of Pure Reason, and Kant became his favorite philosopher, his tutor stating: "At the time he was still a child, only thirteen years old, yet Kant's works, incomprehensible to ordinary mortals, seemed to be clear to him."[24]

In 1895, at the age of 16, Einstein took the entrance examinations for the Swiss Federal Polytechnic in Zürich (later the Eidgenössische Technische Hochschule, ETH). He failed to reach the required standard in the general part of the examination,[26] but obtained exceptional grades in physics and mathematics.[27] On the advice of the principal of the Polytechnic, he attended the Argovian cantonal school (gymnasium) in Aarau, Switzerland, in 1895 and 1896 to complete his secondary schooling. While lodging with the family of professor Jost Winteler, he fell in love with Winteler's daughter, Marie. Albert's sister Maja later married Winteler's son Paul.[28] In January 1896, with his father's approval, Einstein renounced his citizenship in the German Kingdom of Württemberg to avoid military service.[29] In September 1896, he passed the Swiss Matura with mostly good grades, including a top grade of 6 in physics and mathematical subjects, on a scale of 1–6.[30] At 17, he enrolled in the four-year mathematics and physics teaching diploma program at the Zürich Polytechnic. Marie Winteler, who was a year older, moved to Olsberg, Switzerland, for a teaching post.

Einstein's future wife, a 20-year old Serbian woman Mileva Marić, also enrolled at the Polytechnic that year. She was the only woman among the six students in the mathematics and physics section of the teaching diploma course. Over the next few years, Einstein and Marić's friendship developed into romance, and they read books together on extra-curricular physics in which Einstein was taking an increasing interest. In 1900, Einstein passed the exams in Maths and Physics and was awarded the Federal Polytechnic teaching diploma.[31] There have been claims that Marić collaborated with Einstein on his 1905 papers,[32][33] known as the Annus Mirabilis papers, but historians of physics who have studied the issue find no evidence that she made any substantive contributions.[34][35][36][37]An early correspondence between Einstein and Marić was discovered and published in 1987 which revealed that the couple had a daughter named "Lieserl", born in early 1902 in Novi Sad where Marić was staying with her parents. Marić returned to Switzerland without the child, whose real name and fate are unknown. The contents of Einstein's letter in September 1903 suggest that the girl was either given up for adoption or died of scarlet fever in infancy.[38][39]
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Einstein, looking relaxed and holding a pipe, stands next to a smiling, well-dressed Elsa who is wearing a fancy hat and fur wrap. She is looking at him.
Einstein with his second wife Elsa, 1921
Einstein and Marić married in January 1903. In May 1904, their son Hans Albert Einstein was born in Bern, Switzerland. Their son Eduard was born in Zürich in July 1910. The couple moved to Berlin in April 1914, but Marić returned to Zürich with their sons after learning that Einstein's chief romantic attraction was his first and second cousin Elsa.[40] They divorced on 14 February 1919, having lived apart for five years.[41] Eduard had a breakdown at about age 20 and was diagnosed with schizophrenia.[42] His mother cared for him and he was also committed to asylums for several periods, finally being committed permanently after her death.[43]

In letters revealed in 2015, Einstein wrote to his early love Marie Winteler about his marriage and his strong feelings for her. He wrote in 1910, while his wife was pregnant with their second child: "I think of you in heartfelt love every spare minute and am so unhappy as only a man can be". He spoke about a "misguided love" and a "missed life" regarding his love for Marie.[44]

Einstein married Elsa Löwenthal in 1919,[45][46] after having a relationship with her since 1912.[47] She was a first cousin maternally and a second cousin paternally.[47] They emigrated to the United States in 1933. Elsa was diagnosed with heart and kidney problems in 1935 and died in December 1936
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By 1908, he was recognized as a leading scientist and was appointed lecturer at the University of Bern. The following year, after giving a lecture on electrodynamics and the relativity principle at the University of Zürich, Alfred Kleiner recommended him to the faculty for a newly created professorship in theoretical physics. Einstein was appointed associate professor in 1909.[61]

Einstein became a full professor at the German Charles-Ferdinand University in Prague in April 1911, accepting Austrian citizenship in the Austro-Hungarian Empire to do so.[62][63] During his Prague stay, he wrote 11 scientific works, five of them on radiation mathematics and on the quantum theory of solids. In July 1912, he returned to his alma mater in Zürich. From 1912 until 1914, he was professor of theoretical physics at the ETH Zurich, where he taught analytical mechanics and thermodynamics. He also studied continuum mechanics, the molecular theory of heat, and the problem of gravitation, on which he worked with mathematician and friend Marcel Grossmann.[64]

On 3 July 1913, he was voted for membership in the Prussian Academy of Sciences in Berlin. Max Planck and Walther Nernst visited him the next week in Zurich to persuade him to join the academy, additionally offering him the post of director at the Kaiser Wilhelm Institute for Physics, which was soon to be established.[65] (Membership in the academy included paid salary and professorship without teaching duties at the Humboldt University of Berlin.) He was officia3lly elected to the academy on 24 July, and he accepted to move to the German Empire the next year. His decision to move to Berlin was aLlso influenced by the prospect of living near his cousin Elsa, with whom he had developed a romantic affair. He joined the academy and thus the Berlin University on 1 April 1914.[66] As World War I broke out that year, the plan for Kaiser Wilhelm Institute for Physics was aborted. The institute was established on 1 October 1917, with Einstein as its director.[67] In 1916, Einstein was elected president of the German Physical Society (1916–1918).[68]

Based on calculations Einstein made in 1911, about his new theory of general relativity, light from another star should be bent by the Sun's gravity. In 1919, that prediction was confirmed by Sir Arthur Eddington during the solar eclipse of 29 May 1919. Those observations were published in the international media, making Einstein world-famous. On 7 November 1919, the leading British newspaper The Times printed a banner headline that read: "Revolution in Science – New Theory of the Universe – Newtonian Ideas Overthrown".[69]

In 1920, he became a Foreign Member of the Royal Netherlands Academy of Arts and Sciences.[70] In 1922, he was awarded the 1921 Nobel Prize in Physics "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect".[10] While the general theory of relativity was still considered somewhat controversial, the citation also does not treat the cited work as an explanation but merely as a discovery of the law, as the idea of photons was considered outlandish and did not receive universal acceptance until the 1924 derivation of the Planck spectrum by S. N. Bose. Einstein was elected a Foreign Member of the Royal Society (ForMemRS) in 1921.[3] He also received the Copley Medal from the Royal Society in 1925.[3]
Einstein visited New York City for the first time on 2 April 1921, where he received an official welcome by Mayor John Francis Hylan, followed by three weeks of lectures and receptions. He went on to deliver several lectures at Columbia University and Princeton University, and in Washington he accompanied representatives of the National Academy of Science on a visit to the White House. On his return to Europe he was the guest of the British statesman and philosopher Viscount Haldane in London, where he met several renowned scientific, intellectual and political figures, and delivered a lecture at King's College London.[71] [72]

He also published an essay, "My First Impression of the U.S.A.," in July 1921, in which he tried briefly to describe some characteristics of Americans, much as had Alexis de Tocqueville, who published his own impressions in Democracy in America (1835).[73] For some of his observations, Einstein was clearly surprised: "What strikes a visitor is the joyous, positive attitude to life ... The American is friendly, self-confident, optimistic, and without envy."[74]:20

In 1922, his travels took him to Asia and later to Palestine, as part of a six-month excursion and speaking tour, as he visited Singapore, Ceylon and Japan, where he gave a series of lectures to thousands of Japanese. After his first public lecture, he met the emperor and empress at the Imperial Palace, where thousands came to watch. In a letter to his sons, he described his impression of the Japanese as being modest, intelligent, considerate, and having a true feel for art.[75] In his own travel diaries from his 192Y2-23 visit to Asia, he expresses some views on the Chinese, Japanese and Indian people, which have been described as xenophobic and racist judgments when they were rediscovered in 2018.[76]

Because of Einstein's travels to the Far East, he was unable to personally accept the Nobel Prize for Physics at the Stockholm award ceremony in December 1922. In his place, the banquet speech was held by a German diplomat, who praised Einstein not only as a scientist but also as an international peacemaker and activist.[77]

On his return voyage, he visited Palestine for 12 days in what would become his only visit to that region. He was greeted as if he were a head of state, rather than a physicist, which included a cannon salute upon arriving at the home of the British high commissioner, Sir Herbert Samuel. During one reception, the building was stormed by people who wanted to see and hear him. In Einstein's talk to the audience, he expressed happiness that the Jewish people were beginning to be recognized as a force in the world.[78]

Einstein visited Spain for two weeks in 1923, where he briefly met Santiago Ramón y Cajal and also received a diploma from King Alfonso XIII naming him a member of the Spanish Academy of Sciences.[79]

From 1922 to 1932, Einstein was a member of the International Committee on Intellectual Cooperation of the League of Nations in Geneva (with a few months of interruption in 1923–1924),[80] a body created to promote international exchange between scientists, researchers, teachers, artists and intellectuals.[81] Originally slated to serve as the Swiss delegate, Secretary-General Eric Drummond was persuaded by Catholic activists Oskar Halecki and Giuseppe Motta to instead have him become the German delegate, thus allowing Gonzague de Reynold to take the Swiss spot, from which he promoted traditionalist Catholic values.[82] Einstein’s former physics professor Hendrik Lorentz and the French chemist Marie Curie were also members of the committee.
In April 1933, Einstein discovered that the new German government had passed laws barring Jews from holding any official positions, including teaching at universities.[90] Historian Gerald Holton describes how, with "virtually no audible protest being raised by their colleagues", thousands of Jewish scientists were suddenly forced to give up their university positions and their names were removed from the rolls of institutions where they were employed.[74]

A month later, Einstein's works were among those targeted by the German Student Union in the Nazi book burnings, with Nazi propaganda minister Joseph Goebbels proclaiming, "Jewish intellectualism is dead."[90] One German magazine included him in a list of enemies of the German regime with the phrase, "not yet hanged", offering a $5,000 bounty on his head.[90L][92] In a subsequent letter to physicist and friend Max Born, who had already emigrated from Germany to England, Einstein wrote, "... I must confess that the degree of their brutality and cowardice came as something of a surprise."[90] After moving to the US, he described the book burnings as a "spontaneous emotional outburst" by those who "shun popular enlightenment," and "more than anything else in the world, fear the influence of men of intellectual independence."[93]

Einstein was now without a permanent home, unsure where he would live and work, and equally worried about the fate of countless other scientists still in Germany. He rented a house in De Haan, Belgium, where he lived for a few months. In late July 1933, he went to England for about six weeks at the personal invitation of British naval officer Commander Oliver Locker-Lampson, who had become friends with Einstein in the preceding years. To protect Einstein, Locker-Lampson had two assistants watch over him at his secluded cottage outside London, with a photo of them carrying shotguns and guarding Einstein, published in the Daily Herald on 24 July 1933.[94][95]

Locker-Lampson took Einstein to meet Winston Churchill at his home, and later, Austen Chamberlain and former Prime Minister Lloyd George.[96] Einstein asked them to help bring Jewish scientists out of Germany. British historian Martin Gilbert notes that Churchill responded immediately, and sent his friend, physicist Frederick Lindemann, to Germany to seek out Jewish scientists and place them in British universities.[97] Churchill later observed that as a result of Germany having driven the Jews out, they had lowered their "technical standards" and put the Allies' technology ahead of theirs.[97]

Einstein later contacted leaders of other nations, including Turkey's Prime Minister, İsmet İnönü, to whom he wrote in September 1933 requesting placement of unemployed German-Jewish scientists. As a result of Einstein's letter, Jewish invitees to Turkey eventually totaled over "1,000 saved individuals".[98]

Locker-Lampson also submitted a bill to parliament to extend British citizenship to Einstein, during which period Einstein made a number of public appearances describing the crisis brewing in Europe.[99] In one of his speeches he denounced Germany's treatment of Jews, while at the same time he introduced a bill promoting Jewish citizenship in Palestine, as they were being denied citizenship elsewhere.[100] In his speech he described Einstein as a "citizen of the world" who should be offered a temporary shelter in the UK.[note 2][101] Both bills failed, however, and Einstein then accepted an earlier offer from the Institute for Advanced Study, in Princeton, New Jersey, US, to become a resident scholar.[99]

Einstein developed an appreciation for music at an early age, and later wrote: "If I were not a physicist, I would probably be a musician. I often think in music. I live my daydreams in music. I see my life in terms of music... I get most joy in life out of music."[125][126]

His mother played the piano reasonably well and wanted her son to learn the violin, not only to instill in him a love of music but also to help him assimilate into German culture. According to conductor Leon Botstein, Einstein began playing when he was 5, although he did not enjoy it at that age.[127]

When he turned 13, he discovered the violin sonatas of Mozart, whereupon "Einstein fell in love" with Mozart's music and studied music more willingly. He taught himself to play without "ever practicing systematically", he said, deciding that "love is a better teacher than a sense of duty."[127] At age 17, he was heard by a school examiner in Aarau as he played Beethoven's violin sonatas, the examiner stating afterward that his playing was "remarkable and revealing of 'great insight'." What struck the examiner, writes Botstein, was that Einstein "displayed a deep love of the music, a quality that was and remains in short supply. Music possessed an unusual meaning for this student."[127]

Music took on a pivotal and permanent role in Einstein's life from that period on. Although the idea of becoming a professional musician himself was not on his mind at any time, among those with whom Einstein played chamber music were a few professionals, and he performed for private audiences and friends. Chamber music had also become a regular part of his social life while living in Bern, Zürich, and Berlin, where he played with Max Planck and his son, among others. He is sometimes erroneously credited as the editor of the 1937 edition of the Köchel catalogue of Mozart's work; that edition was prepared by Alfred Einstein, who may have been a distant relation.[128][129]

In 1931, while engaged in research at the California Institute of Technology, he visited the Zoellner family conservatory in Los Angeles, where he played some of Beethoven and Mozart's works with members of the Zoellner Quartet.[130][131] Near the end of his life, when the young Juilliard Quartet visited him in Princeton, he played his violin with them, and the quartet was "impressed by Einstein's level of coordination and intonation".[127]