Albert Einstein (14 March 1879 – 18 April 1955) was a German-born theoretical physicist primarily recognized for his development of the theory of relativity. He also significantly advanced quantum theory. His mass–energy equivalence formula, E = mc2, derived from special relativity, is widely regarded as "the world's most famous equation". In 1921, he was awarded the Nobel Prize in Physics for "his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect".
Albert Einstein (14 March 1879 – 18 April 1955) was a German-born theoretical physicist best known for developing the theory of relativity. Einstein also made important contributions to quantum theory. His mass–energy equivalence formula E = mc§78§, which arises from special relativity, has been called "the world's most famous equation". 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".
Born a subject of the Kingdom of Württemberg, then part of the German Empire, Einstein relocated to Switzerland in 1895, renouncing his German citizenship the subsequent year. At seventeen, in 1897, he matriculated into the mathematics and physics teaching diploma program at the Swiss Federal Polytechnic School in Zurich, completing his studies in 1900. A year later, he obtained Swiss citizenship, which he retained throughout his life, subsequently securing a permanent role at the Swiss Patent Office in Bern. His successful doctoral dissertation was submitted to the University of Zurich in 1905. By 1914, he had moved to Berlin, joining the Prussian Academy of Sciences and Humboldt University, and was appointed director of the Kaiser Wilhelm Institute for Physics in 1917; during this period, he also regained Prussian and, by extension, German citizenship. In 1933, during a Appalled by the Nazi persecution of Jews, he chose to remain in the U.S., acquiring American citizenship in 1940. Prior to World War II, he endorsed a letter to President Franklin D. Roosevelt, cautioning about Germany's potential nuclear weapons program and advocating for similar research by the U.S., which subsequently materialized as the Manhattan Project.
During 1905, often referred to as his annus mirabilis (miracle year), Einstein published four seminal papers. These publications presented a theory of the photoelectric effect, elucidated Brownian motion, introduced his special theory of relativity, and established the equivalence of mass and energy contingent on the validity of the special theory. By 1915, he had proposed a general theory of relativity, expanding his mechanical framework to integrate gravitation. A subsequent paper, published the following year, detailed the implications of general relativity for modeling the universe's overall structure and evolution. This work introduced the cosmological constant and is considered a foundational contribution to modern theoretical cosmology. In 1917, Einstein authored a paper introducing the concepts of spontaneous and stimulated emission, with the latter forming the fundamental mechanism for lasers and masers. This publication provided crucial insights that would later prove instrumental for advancements in physics, including quantum electrodynamics and quantum optics.
During the mid-period of his career, Einstein significantly contributed to statistical mechanics and quantum theory. His work on the quantum physics of radiation, positing light as composed of particles (later termed photons), was particularly noteworthy. Collaborating with physicist Satyendra Nath Bose, he established the foundations for Bose–Einstein statistics. Throughout a significant portion of his later academic career, Einstein pursued two undertakings that ultimately did not achieve their intended success. Firstly, he opposed the integration of fundamental randomness into the scientific worldview by quantum theory, famously stating, "God does not play dice". Secondly, he endeavored to formulate a unified field theory by extending his geometric theory of gravitation to encompass electromagnetism. Consequently, he grew increasingly detached from the prevailing currents of modern physics. Numerous entities are named in his honor, including the element Einsteinium. In 1999, Time magazine designated him the Person of the Century.
Biography and Professional Trajectory
Early Life and Education
Albert Einstein was born in Ulm, within the Kingdom of Württemberg, German Empire, on March 14, 1879. His parents were Hermann Einstein, a salesman and engineer, and Pauline Koch, both secular Ashkenazi Jews. In 1880, the family relocated to Munich's Ludwigsvorstadt-Isarvorstadt borough, where Einstein's father and his uncle Jakob established Elektrotechnische Fabrik J. Einstein & Cie, a firm specializing in the manufacture of direct current electrical equipment.
In his early childhood, Einstein's parents expressed concern regarding a potential learning disability due to his delayed speech development. At the age of five, while confined to bed with illness, his father presented him with a compass, an event that ignited a profound and enduring fascination with electromagnetism. This experience led him to the realization that "Something deeply hidden had to be behind things."
From the age of five, Einstein attended St. Peter's Catholic elementary school in Munich. At eight years old, he transferred to the Luitpold Gymnasium, where he pursued advanced primary and subsequently secondary education.
In 1894, the company owned by Hermann and Jakob Einstein submitted a bid for a contract to install electric lighting in Munich. Their proposal was unsuccessful, primarily due to insufficient capital required to upgrade their technology from direct current to the more efficient alternating current system. This commercial setback necessitated the sale of their Munich factory and a relocation in pursuit of new ventures. Consequently, the Einstein family moved to Italy, initially residing in Milan before settling in Palazzo Cornazzani in Pavia a few months later. The fifteen-year-old Einstein remained in Munich to complete his education. Although his father intended for him to pursue electrical engineering, Einstein proved to be a challenging student, finding the Gymnasium's strict regimen and pedagogical approaches uncongenial. He subsequently articulated that the institution's emphasis on rote learning was detrimental to creative development. By the end of December 1894, a physician's letter successfully petitioned the Luitpold authorities for his release, allowing him to join his family in Pavia. During his teenage years in Italy, he authored an essay titled "On the Investigation of the State of the Ether in a Magnetic Field".
Einstein demonstrated exceptional aptitude in physics and mathematics from an early age, rapidly developing mathematical expertise typically observed in individuals several years older. At the age of twelve, he commenced self-study in algebra, calculus, and Euclidean geometry. His progress was remarkably swift, leading him to independently derive an original proof of the Pythagorean theorem prior to his thirteenth birthday. Max Talmud, a family tutor, recounted that shortly after providing the twelve-year-old Einstein with a geometry textbook, the boy "had worked through the whole book. He thereupon devoted himself to higher mathematics... Soon the flight of his mathematical genius was so high I could not follow." Einstein himself documented having "mastered integral and differential calculus" by the age of fourteen. His profound appreciation for algebra and geometry led him, at twelve, to confidently assert that nature could be comprehended as a "mathematical structure".
By the age of thirteen, Einstein's intellectual interests had expanded to encompass music and philosophy. During this period, Talmud introduced him to Kant's Critique of Pure Reason. Kant subsequently became his preferred philosopher; Talmud observed that "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."
In 1895, at sixteen years old, Einstein undertook the entrance examination for the federal polytechnic school (subsequently known as the Eidgenössische Technische Hochschule, ETH) in Zurich, Switzerland. Although he did not achieve the requisite score in the general section of the examination, he demonstrated exceptional proficiency in physics and mathematics. Following the principal's recommendation, he completed his secondary education at the Argovian cantonal school (a gymnasium) in Aarau, Switzerland, graduating in 1896. During his residency in Aarau with the family of Jost Winteler, he developed a romantic relationship with Winteler's daughter, Marie. (His sister, Maja, later married Paul, Jost Winteler's son.)
In January 1896, with his father's consent, Einstein relinquished his citizenship in the German Kingdom of Württemberg to evade military conscription. The Matura (a diploma signifying successful completion of higher secondary education), which he received in September 1896, attested to his strong academic performance across most subjects, earning him a top grade of 6 in history, physics, algebra, geometry, and descriptive geometry. At the age of seventeen, he enrolled in the four-year mathematics and physics teaching diploma program at the federal polytechnic school. There, he formed a friendship with fellow student Marcel Grossmann, who assisted him in navigating his studies despite his unconventional approach and later helped provide mathematical foundations for his groundbreaking physical theories. Marie Winteler, who was a year his senior, secured a teaching position in Olsberg, Switzerland.
Among the five other freshmen pursuing the same curriculum as Einstein at the polytechnic school, only one was a woman: Mileva Marić, a twenty-year-old Serbian student. Over the subsequent years, the pair devoted considerable time to discussing their shared interests and exploring advanced physics topics beyond the scope of the polytechnic school's lectures. In his correspondence with Marić, Einstein confessed that collaborative scientific exploration with her was significantly more engaging than solitary textbook study. Ultimately, their relationship evolved from friendship into a romantic partnership.
Scholarly opinion among historians of physics remains divided regarding the degree of Marić's contribution to the intellectual content of Einstein's annus mirabilis publications. While some evidence suggests he was influenced by her scientific concepts, other scholars question the overall significance of her impact on his intellectual development.
Marriages, Relationships, and Offspring
Correspondence between Einstein and Marić, discovered and published in 1987, brought to light that the couple had a daughter, Lieserl. She was born in early 1902 during Marić's Upon Marić's return to Switzerland, the child was no longer present. Lieserl's fate remains uncertain; in a letter from September 1903, Einstein posited that the child was either adopted or succumbed to scarlet fever during infancy.
Einstein and Marić were married in January 1903. In May 1904, their first son, Hans Albert, was born in Bern, Switzerland, followed by their second son, Eduard, born in Zurich in July 1910. In letters Einstein wrote to Marie Winteler in the months preceding Eduard's birth, he characterized his affection for his wife as "misguided" and lamented a "missed life" he envisioned having enjoyed had he married Winteler instead: "I think of you in heartfelt love every spare minute and am so unhappy as only a man can be."
In 1912, Einstein commenced a relationship with Elsa Löwenthal, who was his first cousin maternally and his second cousin paternally. When Marić discovered his infidelity shortly after relocating to Berlin with him in April 1914, she returned to Zurich, accompanied by Hans Albert and Eduard. Einstein and Marić were divorced on 14 February 1919, citing five years of separation. As part of the divorce settlement, Einstein stipulated that any Nobel Prize winnings he received would be awarded to Marić; he subsequently received the prize two years later.
Einstein married Löwenthal in 1919. In 1923, he initiated a relationship with Betty Neumann, a secretary who was the niece of his close friend Hans Mühsam. Löwenthal nevertheless maintained her loyalty, accompanying him during his emigration to the United States in 1933. In 1935, she received a diagnosis of cardiac and renal issues, and her death occurred in December 1936.
A collection of Einstein's letters, published by Hebrew University of Jerusalem in 2006, revealed additional romantic involvements. These included Margarete Lebach (a married Austrian), Estella Katzenellenbogen (a wealthy florist proprietor), Toni Mendel (a prosperous Jewish widow), and Ethel Michanowski (a Berlin socialite), with whom he spent time and from whom he accepted gifts during his marriage to Löwenthal. Following Löwenthal's death, Einstein briefly engaged in a relationship with Margarita Konenkova, whom some speculate was a Russian spy; her husband, the Russian sculptor Sergei Konenkov, is credited with creating the bronze bust of Einstein located at the Institute for Advanced Study in Princeton.
Eduard, son of Einstein, received a diagnosis of schizophrenia around the age of twenty, following a severe mental health episode. He subsequently spent his life either under his mother's care or in intermittent institutionalization. Following her demise, he was permanently institutionalized at Burghölzli, the Psychiatric University Hospital in Zurich.
Assistantship at the Swiss Patent Office (1902–1909)
In 1900, Einstein graduated from the federal polytechnic school, qualified to teach mathematics and physics. Although he successfully acquired Swiss citizenship in February 1901, he was exempted from customary military conscription, as Swiss authorities deemed him medically unfit for service. Despite nearly two years of applications, he was unable to secure a teaching position in Swiss schools. Ultimately, with the assistance of Marcel Grossmann's father, he obtained a position as an assistant examiner (level III) at the Swiss Patent Office in Bern.
Among the patent applications submitted for Einstein's evaluation were proposals for a gravel sorter and an electric typewriter. His employers, satisfied with his performance, granted him a permanent position in 1903, though they deferred his promotion until he had "fully mastered machine technology." It is plausible that his work at the patent office influenced the development of his special theory of relativity. His groundbreaking concepts concerning space, time, and light emerged from thought experiments involving signal transmission and clock synchronization, topics that were also pertinent to some of the inventions he assessed.
In 1902, Einstein and a circle of acquaintances in Bern established a discussion group that convened regularly to deliberate on science and philosophy. Their selection of the name "Olympia Academy" for their association served as an ironic commentary on its modest, non-academic standing. Marić occasionally joined their sessions, primarily observing the discussions. The group analyzed the works of thinkers such as Henri Poincaré, Ernst Mach, and David Hume, all of whom profoundly shaped Einstein's subsequent intellectual development.
Initial Scientific Publications (1900–1905)
Einstein's inaugural paper, "Folgerungen aus den Capillaritätserscheinungen" ("Conclusions drawn from the phenomena of capillarity"), which proposed a model of intermolecular attraction he subsequently repudiated as insubstantial, was published in the journal Annalen der Physik in 1901. His 24-page doctoral dissertation also focused on a subject in molecular physics. Entitled "Eine neue Bestimmung der Moleküldimensionen" ("A New Determination of Molecular Dimensions") and dedicated "Meinem Freunde Herr Dr. Marcel Grossmann gewidmet" (to his friend Marcel Grossman), it was finalized on 30 April 1905 and subsequently approved by Professor Alfred Kleiner of the University of Zurich three months later. (Einstein was officially conferred his doctorate on 15 January 1906.) Four additional seminal works completed by Einstein in 1905—his renowned papers on the photoelectric effect, Brownian motion, his special theory of relativity, and the equivalence of mass and energy—resulted in the designation of that year as an annus mirabilis for physics, comparable to the pivotal year of 1666 when Isaac Newton achieved his most significant intellectual breakthroughs. These publications profoundly impressed Einstein's contemporaries.
European Academic Career (1908–1933)
Einstein's tenure as a civil servant concluded in 1908, when he obtained an entry-level academic appointment at the University of Bern. In 1909, a lecture on relativistic electrodynamics delivered at the University of Zurich, highly regarded by Alfred Kleiner, prompted the University of Zurich to recruit him with a newly established associate professorship. His promotion to a full professorship followed in April 1911, when he assumed a professorial chair at the German Charles-Ferdinand University in Prague. This relocation necessitated his acquisition of Austro-Hungarian citizenship, a process that remained unfinalized. His period in Prague was marked by the production of eleven research papers.
From October 30 to November 3, 1911, Einstein participated in the inaugural Solvay Conference on Physics.
In July 1912, he rejoined his alma mater, ETH Zurich, to assume a professorship in theoretical physics. His pedagogical activities there focused on thermodynamics and analytical mechanics, while his research encompassed the molecular theory of heat, continuum mechanics, and the formulation of a relativistic theory of gravitation. For his work on the latter subject, he collaborated with his friend Marcel Grossmann, whose mathematical expertise surpassed his own.
In the spring of 1913, Max Planck and Walther Nernst, two German visitors, called upon Einstein in Zurich with the aim of convincing him to relocate to Berlin. They extended an offer of membership in the Prussian Academy of Sciences, the directorship of the proposed Kaiser Wilhelm Institute for Physics, and a professorship at the Humboldt University of Berlin, which would provide a professorial salary for research without teaching obligations. This invitation was particularly attractive to him, as Berlin was the residence of his then-girlfriend, Elsa Löwenthal. He subsequently accepted the Academy membership on July 24, 1913, and relocated to an apartment in the Berlin district of Dahlem on April 1, 1914. He assumed his position at Humboldt University soon after.
The commencement of the First World War in July 1914 initiated Einstein's progressive alienation from his native country. When the "Manifesto of the Ninety-Three" was published in October 1914—a document endorsed by numerous leading German intellectuals that rationalized Germany's aggressive stance—Einstein was among the limited number of German intellectuals who disavowed it, opting instead to sign the alternative, pacifist "Manifesto to the Europeans." However, despite this articulation of his reservations regarding German policy, he was nevertheless elected to a two-year term as president of the German Physical Society in 1916. When the Kaiser Wilhelm Institute for Physics commenced operations the subsequent year, its establishment having been postponed due to the conflict, Einstein was appointed its first director, in accordance with the prior assurances from Planck and Nernst.
Einstein was appointed a Foreign Member of the Royal Netherlands Academy of Arts and Sciences in 1920 and a Foreign Member of the Royal Society in 1921. In 1922, he was conferred the 1921 Nobel Prize in Physics "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect." At this juncture, certain physicists maintained skepticism regarding the general theory of relativity, and the Nobel citation evinced a measure of reservation even concerning the acknowledged work on photoelectricity: it did not endorse Einstein's concept of the particulate nature of light, a concept that gained universal scientific acceptance only after S. N. Bose's derivation of the Planck spectrum in 1924. In the same year, Einstein received election as an International Honorary Member of the American Academy of Arts and Sciences. The Copley Medal of the Royal Society, considered Britain's most analogous award to the Nobel Prize, was not bestowed upon Einstein until 1925. He was subsequently elected an International Member of the American Philosophical Society in 1930.
Einstein tendered his resignation from the Prussian Academy in March 1933. His notable achievements during his tenure in Berlin encompassed the completion of the general theory of relativity, the demonstration of the Einstein–de Haas effect, significant contributions to the quantum theory of radiation, and the pioneering development of Bose–Einstein statistics.
Experimental Verification of General Relativity (1919)
In 1907, Albert Einstein achieved a significant breakthrough in his progression from the special theory of relativity to a novel gravitational concept, formulating the equivalence principle. This principle posited that an observer within a freely falling enclosure in a gravitational field would detect no evidence of that field's presence. By 1911, he applied this principle to calculate the deflection of light rays from distant stars due to the Sun's gravitational influence as they traversed near its photosphere, or apparent surface. His calculations were refined in 1913, incorporating a method to model gravitation using the Riemann curvature tensor within a non-Euclidean, four-dimensional spacetime. By late 1915, his comprehensive re-conceptualization of gravitational mathematics through Riemannian geometry was finalized. He then applied this new theory to explain not only the Sun's function as a gravitational lens but also the precession of Mercury's perihelion—a gradual shift in the point of its elliptical orbit closest to the Sun. A total solar eclipse on May 29, 1919, offered a crucial opportunity to empirically validate his gravitational lensing theory. Observations conducted by Sir Arthur Eddington subsequently confirmed Einstein's predictions. Eddington's findings garnered extensive global media attention. For instance, on November 7, 1919, the prominent British newspaper, The Times, featured a prominent headline proclaiming: "Revolution in Science– New Theory of the Universe– Newtonian Ideas Overthrown".
Navigating Public Acclaim (1921–1923)
The extensive dissemination of Eddington's eclipse observations, both in scholarly publications and popular media, propelled Einstein to an unprecedented level of public recognition, establishing him as "perhaps the world's first celebrity scientist." His groundbreaking work was lauded for fundamentally disrupting a scientific paradigm that had underpinned physicists' comprehension of the cosmos since the seventeenth century.
Einstein commenced his role as an intellectual luminary in the United States, arriving on April 2, 1921. His reception in New York City included a welcome from Mayor John Francis Hylan, followed by a three-week itinerary of lectures and formal receptions. He delivered multiple addresses at Columbia University and Princeton, and in Washington, D.C., he visited the White House alongside delegates from the National Academy of Sciences. His return journey to Europe included a stop in London, where he was hosted by the distinguished philosopher and statesman Viscount Haldane. During his stay in the British capital, Einstein engaged with several prominent figures across British scientific, political, and intellectual spheres, and presented a lecture at King's College. In July 1921, he authored an essay titled "My First Impression of the U.S.A.," aiming to delineate the American national character, a endeavor reminiscent of Alexis de Tocqueville's observations in Democracy in America (1835). He expressed considerable admiration for his American hosts, remarking: "What strikes a visitor is the joyous, positive attitude to life ... The American is friendly, self-confident, optimistic, and without envy."
In 1922, Einstein's travels focused on the Eastern Hemisphere instead of the Western. He embarked on a six-month tour of Asia, delivering lectures in Japan, Singapore, and Ceylon (now Sri Lanka). Following his initial public lecture in Tokyo, he was received by Emperor Yoshihito and his wife at the Imperial Palace, while thousands of onlookers gathered in the streets, hoping to see him. While he noted in a letter to his sons that Japanese people appeared modest, intelligent, considerate, and appreciative of art, his private diary entries offered a less favorable perspective, questioning whether their intellectual needs were weaker than their artistic ones. His journal also contained critical observations regarding Chinese and Indian populations, including a remark about Chinese children appearing "spiritless and obtuse" and expressing a concern about the potential for Chinese people to "supplant all other races," which he found "unspeakably dreary." The final segment of his tour, a twelve-day Sir Herbert Samuel, the British High Commissioner, extended a welcome typically reserved for a visiting head of state, complete with a cannon salute. During a reception in his honor, a crowd eager to hear him speak overwhelmed the event; he addressed them by expressing his satisfaction that Jewish people were gaining recognition as a global influence.
On April 6, 1922, while in Paris, Einstein participated in a debate concerning relativity with the philosopher Henri Bergson. This intellectual disagreement significantly impacted the humanities and was considered an academic cause célèbre during that period.
Einstein's choice to undertake an Eastern Hemisphere tour in 1922 precluded his attendance at the Nobel Prize ceremony in Stockholm that December. A German diplomat represented him at the customary Nobel banquet, delivering a speech that lauded Einstein not only for his contributions to physics but also for his advocacy for peace. A subsequent two-week During his Spanish journey, he also had the opportunity to meet Santiago Ramón y Cajal, a fellow Nobel laureate and neuroanatomist.
Service with the League of Nations (1922–1932)
From 1922 to 1932, with brief interruptions in 1923 and 1924, Einstein served on the International Committee on Intellectual Cooperation of the League of Nations, based in Geneva. This committee was established by the League to foster closer collaboration among scientists, artists, scholars, educators, and other intellectuals across national borders. His appointment was as a German delegate, not a Swiss representative, a result of maneuvers by two Catholic activists, Oskar Halecki and Giuseppe Motta. They influenced Secretary General Eric Drummond to withhold the committee position designated for a Swiss intellectual from Einstein, thereby creating an opportunity for Gonzague de Reynold, who subsequently utilized his League of Nations role to advocate for traditional Catholic doctrine. Hendrik Lorentz, Einstein's former physics professor, and the Polish chemist Marie Curie were also members of this committee.
South American Tour (1925)
During March and April 1925, Einstein and his wife undertook a tour of South America, spending approximately one week in Brazil, one week in Uruguay, and one month in Argentina. The tour was proposed by Jorge Duclout (1856–1927) and Mauricio Nirenstein (1877–1935), with backing from Argentine scholars such as Julio Rey Pastor, Jakob Laub, and Leopoldo Lugones. Funding was primarily provided by the Council of the University of Buenos Aires and the Asociación Hebraica Argentina (Argentine Hebraic Association), supplemented by a smaller contribution from the Argentine-Germanic Cultural Institution.
United States Tour (1930–1931)
In December 1930, Albert Einstein commenced another notable Caltech accommodated his preference to avoid the extensive media attention he had encountered during his 1921 S., leading him to decline numerous invitations for awards and speeches from his admirers. Nevertheless, he remained willing to allocate some time to meet with his fans upon request.
Following his arrival in New York City, Einstein participated in various engagements, including a In the subsequent days, Mayor Jimmy Walker presented him with the keys to the city, and he met Nicholas Murray Butler, the president of Columbia University, who characterized Einstein as "the ruling monarch of the mind." Harry Emerson Fosdick, pastor of New York's Riverside Church, conducted a tour for Einstein, showcasing a life-size statue of him positioned at the church's entrance. During his New York stay, Einstein also joined approximately 15,000 individuals at Madison Square Garden for a Hanukkah celebration.
Einstein subsequently traveled to California, where he met Robert A. Millikan, the president of Caltech and a Nobel laureate. Their friendship was described as "awkward" due to Millikan's "penchant for patriotic militarism," which contrasted sharply with Einstein's pronounced pacifism. During an address to Caltech students, Einstein remarked that science frequently tended to cause more harm than good.
This strong aversion to warfare also fostered Einstein's friendships with author Upton Sinclair and film star Charlie Chaplin, both recognized for their pacifist stances. Carl Laemmle, the head of Universal Studios, provided Einstein with a studio tour and introduced him to Chaplin. They developed an immediate rapport, leading Chaplin to invite Einstein and his wife, Elsa, to his residence for dinner. Chaplin observed that Einstein's outwardly calm and gentle demeanor appeared to conceal a "highly emotional temperament," which he believed fueled his "extraordinary intellectual energy."
Chaplin's film City Lights was scheduled to premiere in Hollywood a few days later, and Chaplin extended an invitation to Einstein and Elsa to attend as his special guests. Walter Isaacson, Einstein's biographer, characterized this event as "one of the most memorable scenes in the new era of celebrity." On a subsequent trip to Berlin, Chaplin visited Einstein at his home, recalling his "modest little flat" and the piano where Einstein had commenced writing his theory. Chaplin speculated that the piano was "possibly used as kindling wood by the Nazis." At the film's premiere, both Einstein and Chaplin received enthusiastic cheers. Chaplin famously remarked to Einstein, "They cheer me because they understand me, and they cheer you because no one understands you."
Emigration to the United States (1933)
In February 1933, while on a
During his time at American universities in early 1933, Einstein undertook his third two-month visiting professorship at the California Institute of Technology in Pasadena. In February and March 1933, the Gestapo conducted repeated raids on his family's apartment in Berlin. He and his wife, Elsa, returned to Europe in March, and during their journey, they learned that the German Reichstag had passed the Enabling Act on March 23, effectively transforming Hitler's government into a de facto legal dictatorship, thereby precluding their return to Berlin. Subsequently, they received news that their cottage had been raided by the Nazis and Einstein's personal sailboat confiscated. Upon disembarking in Antwerp, Belgium, on March 28, Einstein immediately proceeded to the German consulate to surrender his passport, formally renouncing his German citizenship. The Nazis later sold his boat and converted his cottage into a Hitler Youth camp.
Refugee Status
In April 1933, Albert Einstein became aware of new German legislation prohibiting Jews from holding public offices, including academic positions at universities. Historian Gerald Holton documented that thousands of Jewish scientists were abruptly dismissed from their university roles and expunged from institutional records, with "virtually no audible protest being raised by their colleagues."
The following month, Einstein's publications were among those targeted by the German Student Union during the Nazi book burnings, a period when Joseph Goebbels, the Nazi propaganda minister, declared, "Jewish intellectualism is dead." Concurrently, a German periodical listed Einstein among the regime's adversaries, stating "not yet hanged" and offering a $5,000 reward for his capture. In a subsequent correspondence with his friend and fellow physicist Max Born, who had already relocated from Germany to England, Einstein admitted, "I must confess that the degree of their brutality and cowardice came as something of a surprise." Following his relocation to the United States, Einstein characterized the book burnings as a "spontaneous emotional outburst" by individuals who "shun popular enlightenment" and, "more than anything else in the world, fear the influence of men of intellectual independence."
Einstein found himself without a permanent residence, uncertain of his future living and working arrangements, and deeply concerned for the numerous scientists remaining in Germany. He received assistance from the Academic Assistance Council, an organization established in April 1933 by British Liberal politician William Beveridge to facilitate the escape of academics from Nazi persecution, enabling him to depart Germany. He subsequently rented a house in De Haan, Belgium, for several months. In late July 1933, he accepted an invitation from British Member of Parliament Commander Oliver Locker-Lampson, with whom he had developed a friendship in previous years, to Locker-Lampson arranged for Einstein to reside in a secluded wooden cabin on Roughton Heath, within the Parish of Roughton, Norfolk, near his Cromer home. To ensure Einstein's safety, Locker-Lampson assigned two bodyguards to him; a photograph depicting them armed with shotguns and protecting Einstein appeared in the Daily Herald on July 24, 1933.
Locker-Lampson facilitated Einstein's meetings with prominent British figures, including Winston Churchill at his residence, followed by Austen Chamberlain and former Prime Minister Lloyd George. During these encounters, Einstein appealed for assistance in relocating Jewish scientists from Germany. British historian Martin Gilbert documented Churchill's prompt action, noting that he dispatched his associate, physicist Frederick Lindemann, to Germany to identify Jewish scientists for placement in British universities. Churchill subsequently remarked that Germany's expulsion of its Jewish population had inadvertently diminished its "technical standards," thereby granting the Allies a technological advantage.
Einstein subsequently extended his outreach to leaders of other nations, including İsmet İnönü, the Prime Minister of Turkey, to whom he wrote in September 1933. His letter sought the placement of unemployed German-Jewish scientists. Consequently, over "1,000 saved individuals" were eventually invited to Turkey as a direct result of Einstein's intervention.
Concurrently, Locker-Lampson presented a parliamentary bill proposing British citizenship for Einstein. During this period, Einstein delivered several public addresses detailing the escalating crisis in Europe. In one such speech, Einstein condemned Germany's persecution of Jews and advocated for Jewish citizenship in Palestine, given their widespread denial of citizenship elsewhere. In support of his legislative proposal, Locker-Lampson characterized Einstein as a "citizen of the world" deserving of temporary asylum in the United Kingdom. Both legislative initiatives ultimately failed. Consequently, Einstein accepted a prior invitation from the Institute for Advanced Study in Princeton, New Jersey, USA, to assume a position as a resident scholar.
Resident Scholar at the Institute for Advanced Study
On October 3, 1933, Einstein delivered a significant address on the imperative of academic freedom to a capacity audience at the Royal Albert Hall in London, a speech that The Times reported was met with enthusiastic applause throughout. Four days later, he returned to the United States to commence his appointment at the Institute for Advanced Study, an institution recognized for serving as a sanctuary for scientists escaping Nazi Germany. It is noteworthy that during this era, the majority of American universities, including prestigious institutions such as Harvard, Princeton, and Yale, maintained minimal or no Jewish faculty or student populations due to restrictive quotas that persisted until the late 1940s.
Einstein's future trajectory remained uncertain. He received multiple offers from European academic institutions, notably a five-year research fellowship (termed a "studentship" within the institution) from Christ Church, Oxford, where he resided for three brief intervals between May 1931 and June 1933. However, by 1935, he resolved to establish permanent residency in the United States and pursue citizenship.
Einstein maintained his association with the Institute for Advanced Study until his demise in 1955. He was among the initial four scholars chosen for the newly established Institute, alongside John von Neumann, Kurt Gödel, and Hermann Weyl. A profound friendship quickly formed between Einstein and Gödel, characterized by their frequent collaborative discussions during walks. His assistant, Bruria Kaufman, subsequently pursued a career as a physicist. Throughout this era, Einstein unsuccessfully endeavored to formulate a unified field theory and to challenge the prevailing interpretation of quantum physics. From 1935, he resided in his Princeton home. In 1976, the Albert Einstein House was designated a National Historic Landmark.
World War II and the Manhattan Project
During 1939, a contingent of Hungarian scientists, including the émigré physicist Leó Szilárd, sought to apprise Washington, D.C., of the ongoing Nazi atomic bomb research. Initially, these warnings were disregarded. Einstein, Szilárd, and other refugees, including Edward Teller and Eugene Wigner, perceived it as their duty to inform Americans about the potential for German scientists to develop an atomic bomb and to caution that Hitler would readily employ such a weapon. To ensure the United States recognized this imminent threat, in July 1939, several months prior to the commencement of World War II in Europe, Szilárd and Wigner met with Einstein to elucidate the concept of atomic bombs, a possibility Einstein, a committed pacifist, admitted he had never contemplated. He was subsequently requested to endorse a letter, co-authored with Szilárd, addressed to President Franklin D. Roosevelt, advocating for U.S. attention to and engagement in its own nuclear weapons research.
This correspondence is widely considered to be "arguably the key stimulus for the U.S. adoption of serious investigations into nuclear weapons on the eve of the U.S. entry into World War II". Beyond the letter, Einstein leveraged his connections with the Belgian royal family and the Belgian queen mother to secure access for a personal envoy to the Oval Office at the White House. It is posited by some that Einstein's letter and subsequent meetings with Roosevelt prompted the United States to join the "race" for atomic bomb development, thereby mobilizing its "immense material, financial, and scientific resources" to launch the Manhattan Project.
Einstein viewed "war as a disease," advocating for resistance against it. His endorsement of the letter to Roosevelt is contended by some as a departure from his pacifist convictions. In 1954, a year prior to his passing, Einstein confided in his long-time friend, Linus Pauling, stating, "I made one great mistake in my life—when I signed the letter to President Roosevelt recommending that atom bombs be made; but there was some justification—the danger that the Germans would make them." During 1955, Einstein, alongside ten other prominent intellectuals and scientists, notably British philosopher Bertrand Russell, co-signed a manifesto emphasizing the existential threat posed by nuclear weaponry. Posthumously, in 1960, Einstein was inducted as a charter member of the World Academy of Art and Science (WAAS), an institution established by eminent scientists and intellectuals dedicated to promoting the responsible and ethical progression of science, especially considering the advent of nuclear weapons.
US Citizenship
Einstein acquired American citizenship in 1940. Shortly after commencing his tenure at the Institute for Advanced Study in Princeton, New Jersey, he articulated his admiration for the meritocratic aspects of American culture, contrasting them with European norms. He acknowledged the "right of individuals to say and think what they pleased," unhindered by societal constraints. Consequently, he observed that individuals were fostered to exhibit greater creativity, a characteristic he had esteemed since his formative educational experiences.
Albert Einstein became a member of the National Association for the Advancement of Colored People (NAACP) in Princeton, actively advocating for the civil rights of African Americans. He characterized racism as America's "worst disease," perceiving it as a phenomenon "handed down from one generation to the next." His engagement included corresponding with civil rights activist W. E. B. Du Bois and expressing readiness to testify on Du Bois's behalf during his 1951 trial, where Du Bois was accused of being a foreign agent. Following Einstein's offer to serve as a character witness, the presiding judge dismissed the case.
In 1946, Einstein received an honorary degree during a Notably, Lincoln University holds the distinction of being the first university in the United States to confer college degrees upon African Americans, with prominent alumni such as Langston Hughes and Thurgood Marshall. During his visit, Einstein delivered a speech addressing racism in America, asserting, "I do not intend to be quiet about it." A Princeton resident recounted that Einstein had previously covered the college tuition for an African American student. Einstein articulated his perspective, stating, "Being a Jew myself, perhaps I can understand and empathize with how black people feel as victims of discrimination." Isaacson documents a significant incident: "When Marian Anderson, the black contralto, came to Princeton for a concert in 1937, the Nassau Inn refused her a room. So Einstein invited her to stay at his house on Main Street, in what was a deeply personal as well as symbolic gesture ... Whenever she returned to Princeton, she stayed with Einstein, her last "
Personal Views
Political Views
In 1918, Einstein was among the initial signatories of the founding proclamation for the German Democratic Party, a liberal political organization. Subsequently, Einstein's political philosophy evolved towards an endorsement of socialism and a critique of capitalism, themes he explored in essays such as "Why Socialism?". His perspectives on the Bolsheviks also underwent a transformation over time. In 1925, he criticized their governance for lacking a "well-regulated system of government" and characterized their rule as a "regime of terror and a tragedy in human history." Later, he adopted a more nuanced stance, acknowledging their methods critically while still offering praise, as evidenced by his 1929 commentary on Vladimir Lenin:
In Lenin I honor a man, who in total sacrifice of his own person has committed his entire energy to realizing social justice. I do not find his methods advisable. One thing is certain, however: men like him are the guardians and renewers of mankind's conscience.
Einstein frequently provided assessments and viewpoints on subjects extending beyond the domains of theoretical physics or mathematics. He was a fervent proponent of a democratic global government designed to constrain the authority of nation-states within a world federation framework. He articulated this conviction, stating, "I advocate world government because I am convinced that there is no other possible way of eliminating the most terrible danger in which man has ever found himself." The Federal Bureau of Investigation (FBI) initiated a confidential dossier on Einstein in 1932, which had expanded to 1,427 pages by the time of his passing.
Mahatma Gandhi profoundly impressed Einstein, leading to their correspondence. Einstein characterized Gandhi as "a role model for the generations to come." Their initial connection was forged on September 27, 1931, when Wilfrid Israel facilitated a meeting between his Indian guest, V. A. Sundaram, and Einstein at his summer residence in Caputh. Sundaram, a disciple and special envoy of Gandhi, had previously met Wilfrid Israel during Israel's 1925 During the Caputh visit, Einstein composed a brief letter to Gandhi, which was conveyed via Sundaram, and Gandhi promptly reciprocated with his own correspondence. Despite their eventual inability to meet in person as desired, Wilfrid Israel was instrumental in establishing this direct communication link between Einstein and Gandhi.
Relationship with Zionism
As a Jewish individual, Einstein played a prominent role in the establishment of the Hebrew University of Jerusalem, which commenced operations in 1925. In 1921, Chaim Weizmann, a biochemist and president of the World Zionist Organization, requested Einstein's assistance in fundraising for the proposed university. Einstein proposed the establishment of an Institute of Agriculture, a Chemical Institute, and an Institute of Microbiology. These institutes were intended to combat prevalent epidemics like malaria, which he characterized as an "evil" impeding a third of the nation's progress. Additionally, he advocated for an Oriental Studies Institute, which would offer language instruction in both Hebrew and Arabic.
Einstein, who was not a nationalist, opposed the formation of an independent Jewish state. He believed that Jewish immigrants arriving through the Aliyah could coexist peacefully with the Arab population already present in Palestine. The State of Israel was established in 1948, a development in which Einstein played only a marginal role within the Zionist movement. Following the death of Israeli President Weizmann in November 1952, Prime Minister David Ben-Gurion, prompted by Ezriel Carlebach, extended an offer to Einstein for the largely ceremonial role of President of Israel. Israel's ambassador in Washington, Abba Eban, conveyed the offer, stating that it "embodies the deepest respect which the Jewish people can repose in any of its sons". Einstein expressed being "deeply moved" but simultaneously "saddened and ashamed" by his inability to accept the position. Although Einstein did not wish to hold the office, and Israel, while feeling compelled to make the offer, did not actually want him to accept it. Yitzhak Navon, who served as Ben-Gurion's political secretary and later became president, recounted Ben-Gurion's apprehension: "Tell me what to do if he says yes! I've had to offer the post to him because it's impossible not to. But if he accepts, we are in for trouble."
Religious and Philosophical Perspectives
According to Lee Smolin, Einstein's significant achievements were primarily attributable to a moral quality: "He simply cared far more than most of his colleagues that the laws of physics have to explain everything in nature coherently and consistently." Einstein articulated his spiritual perspective across numerous writings and interviews. He expressed affinity for the impersonal, pantheistic God described in Baruch Spinoza's philosophy. He rejected the concept of a personal God involved in human destinies and actions, characterizing this view as naive. However, he clarified, "I am not an atheist," preferring to identify as an agnostic or a "deeply religious nonbeliever." He further wrote that "A spirit is manifest in the laws of the universe—a spirit vastly superior to that of man, and one in the face of which we with our modest powers must feel humble. In this way the pursuit of science leads to a religious feeling of a special sort."
Einstein maintained primary affiliations with non-religious humanist and Ethical Culture organizations in both the United Kingdom and the United States. He served on the advisory board of the First Humanist Society of New York and was an honorary associate of the Rationalist Association, which publishes New Humanist in Britain. On the occasion of the 75th anniversary of the New York Society for Ethical Culture, he affirmed that the principles of Ethical Culture encapsulated his personal understanding of the most valuable and enduring aspects of religious idealism. He remarked, "Without 'ethical culture' there is no salvation for humanity."
In a letter written in German to philosopher Eric Gutkind, dated January 3, 1954, Einstein articulated:
The word God is for me nothing more than the expression and product of human weaknesses, the Bible a collection of honorable, but still primitive legends which are nevertheless pretty childish. No interpretation no matter how subtle can (for me) change this. ... For me the Jewish religion like all other religions is an incarnation of the most childish superstitions. And the Jewish people to whom I gladly belong and with whose mentality I have a deep affinity have no different quality for me than all other people. ... I cannot see anything 'chosen' about them.
Einstein had long held sympathetic views toward vegetarianism. In a 1930 letter addressed to Hermann Huth, vice-president of the German Vegetarian Federation (Deutsche Vegetarier-Bund), he stated:
Despite external constraints that precluded a strictly vegetarian diet, I have consistently supported the principle of vegetarianism. Beyond the aesthetic and moral justifications for its objectives, I believe that a vegetarian lifestyle, through its physiological impact on human disposition, would profoundly enhance the welfare of humanity.
Einstein adopted a vegetarian diet only in the latter period of his life. In a letter dated March 1954, he remarked: "Consequently, I am subsisting without fats, meat, or fish, yet I feel quite well. It almost appears to me that humans were not inherently designed to be carnivores."
Musical Affinities
Einstein cultivated an early appreciation for music, as evidenced by entries in his later journals:
Were I not a physicist, I would likely be a musician. I frequently engage in musical thought, and my daydreams are often set to music. I perceive my life through a musical lens... Music is the primary source of joy in my life.
His mother, a competent pianist, desired for her son to learn the violin, aiming both to cultivate his musical appreciation and to facilitate his integration into German society. Conductor Leon Botstein notes that Einstein commenced playing the violin at age five, though he did not find enjoyment in it at that time.
Upon reaching the age of 13, Einstein encountered Mozart's violin sonatas, which sparked his profound admiration for Mozart's works and fostered a more enthusiastic approach to musical study. He was self-taught, reportedly without "ever practicing systematically," asserting that "love is a better teacher than a sense of duty." At 17, a school examiner in Aarau observed his performance of Beethoven's violin sonatas, subsequently describing his playing as "remarkable and revealing of 'great insight'." Botstein highlights that the examiner was particularly impressed by Einstein's "deep love of the music, a quality that was and remains in short supply," noting that "Music possessed an unusual meaning for this student."
From that point forward, music assumed a pivotal and enduring significance in Einstein's life. While he never contemplated a career as a professional musician, he engaged in chamber music with several professionals, including Kurt Appelbaum, and performed for private gatherings and acquaintances. Chamber music also became an integral component of his social engagements during his residences in Bern, Zurich, and Berlin, where he played alongside figures such as Max Planck and his son. It is occasionally misattributed that he edited the 1937 edition of the Köchel catalog of Mozart's compositions; that particular edition was compiled by Alfred Einstein, who might have been a distant relative. Mozart held a special place in his affections, with Einstein remarking that "Mozart's music is so pure it seems to have been ever-present in the universe." Nevertheless, he expressed a preference for Bach over Beethoven, once stating: "Give me Bach, rather, and then more Bach."
In 1931, during his research tenure at the California Institute of Technology, Einstein visited the Zoellner family conservatory in Los Angeles, where he performed selections from Beethoven and Mozart with members of the Zoellner Quartet. Towards the end of his life, upon a "
Death
On April 17, 1955, Einstein suffered an internal hemorrhage resulting from the rupture of an abdominal aortic aneurysm, a condition that Rudolph Nissen had surgically reinforced in 1948. He brought with him to the hospital a draft of a speech intended for a television broadcast commemorating the seventh anniversary of the state of Israel, but he passed away before its completion.
Einstein declined surgical intervention, stating: "I want to go when I want. It is tasteless to prolong life artificially. I have done my share; it is time to go. I will do it elegantly." He passed away at Princeton Hospital early the following morning at the age of 76, having maintained his work until shortly before his death.
During the subsequent autopsy, pathologist Thomas Stoltz Harvey controversially extracted Einstein's brain for preservation, without familial consent, driven by the aspiration that future neuroscientific advancements might elucidate the biological underpinnings of Einstein's exceptional intellect. Einstein's remains were cremated in Trenton, New Jersey, and his ashes were dispersed at an undisclosed site.
On December 13, 1965, during a memorial lecture at UNESCO headquarters, nuclear physicist J. Robert Oppenheimer characterized Albert Einstein's personality, stating: "He was almost wholly without sophistication and wholly without worldliness... There was always with him a wonderful purity at once childlike and profoundly stubborn."
Einstein bequeathed his personal archives, library, and intellectual assets to the Hebrew University of Jerusalem in Israel.
Scientific Career
Throughout his lifetime, Einstein authored hundreds of publications, including over 300 scientific papers and 150 non-scientific articles. On December 5, 2014, universities and archives jointly announced the release of Einstein's collected papers, which encompass more than 30,000 unique documents. Beyond his individual contributions, he also engaged in collaborations with other scientists on various projects, such as the Bose–Einstein statistics and the Einstein refrigerator.
Statistical Mechanics
Thermodynamic Fluctuations and Statistical Physics
Einstein's inaugural paper, submitted in 1900 to Annalen der Physik, focused on capillary attraction and was published in 1901 under the title "Folgerungen aus den Capillaritätserscheinungen" (Conclusions from the capillarity phenomena). Subsequently, two papers published in 1902–1903 explored thermodynamic principles, aiming to interpret atomic phenomena from a statistical perspective. These foundational works paved the way for his 1905 paper on Brownian motion, which demonstrated that Brownian movement provides compelling evidence for the existence of molecules. His investigations during 1903 and 1904 primarily addressed the influence of finite atomic size on diffusion phenomena.
Theory of Critical Opalescence
Einstein revisited the issue of thermodynamic fluctuations, providing an analysis of density variations within a fluid at its critical point. Typically, density fluctuations are governed by the second derivative of the free energy concerning density. However, at the critical point, this derivative becomes zero, resulting in substantial fluctuations. These density fluctuations cause light across all wavelengths to scatter, imparting a milky white appearance to the fluid. Einstein connected this phenomenon to Rayleigh scattering, which occurs when fluctuation sizes are significantly smaller than the wavelength and accounts for the blue color of the sky. He quantitatively derived critical opalescence through an examination of density fluctuations, thereby demonstrating that both this effect and Rayleigh scattering stem from the atomistic composition of matter.
1905 – Annus Mirabilis Papers
The Annus Mirabilis papers comprise four articles published by Einstein in the scientific journal Annalen der Physik during 1905. These seminal works addressed the photoelectric effect (which initiated quantum theory), Brownian motion, the special theory of relativity, and the mass-energy equivalence formula E = mc§1011§. Collectively, these four papers significantly contributed to the bedrock of modern physics and fundamentally altered perspectives on space, time, and matter. The four papers are:
Special Relativity
Einstein's seminal paper, "On the electrodynamics of moving bodies" ("On the Electrodynamics of Moving Bodies"), was submitted on June 30, 1905, and subsequently published on September 26 of the same year. This work resolved inconsistencies between Maxwell's equations (governing electricity and magnetism) and the principles of Newtonian mechanics by proposing modifications to the laws of mechanics. Empirically, the ramifications of these alterations become most evident at relativistic speeds, where objects approach the speed of light. The theoretical framework established in this paper subsequently evolved into Einstein's special theory of relativity.
This publication posited that, from the perspective of a relatively moving observer, a clock affixed to a moving body would exhibit time dilation, and the body itself would undergo length contraction in its direction of motion. Furthermore, the paper contended that the concept of a luminiferous aether—a prominent theoretical construct in physics during that era—was unnecessary.
In his treatise on mass–energy equivalence, Einstein derived the formula E=mc§89§ as a direct consequence of his special relativity equations. Although Einstein's 1905 work on relativity initially faced considerable debate for several years, it eventually gained acceptance among prominent physicists, notably beginning with Max Planck.
Einstein initially formulated special relativity using kinematics, which is the study of moving bodies. In 1908, Hermann Minkowski reconceptualized special relativity geometrically as a theory of spacetime. Einstein subsequently integrated Minkowski's formalism into his 1915 general theory of relativity.
General Relativity
General Relativity and the Equivalence Principle
General Relativity (GR) is a theory of gravitation formulated by Einstein from 1907 to 1915. This theory posits that the gravitational attraction observed between masses arises from the distortion of spacetime induced by these masses. General Relativity has become a fundamental instrument in modern astrophysics, underpinning contemporary comprehension of black holes, which are regions of space where gravitational attraction is so intense that even light cannot escape.
Einstein later articulated that the impetus for developing general relativity stemmed from the unsatisfactory preference for inertial motions within special relativity, suggesting that a theory inherently impartial to any state of motion, including accelerated ones, would be more satisfactory. Accordingly, in 1907, he published an article addressing acceleration within the framework of special relativity. Within this article, titled "On the Relativity Principle and the Conclusions Drawn from It," he posited that free fall constitutes genuine inertial motion, and consequently, the principles of special relativity must be applicable to an observer in free fall. This proposition is known as the equivalence principle. Furthermore, in the same publication, Einstein predicted the phenomena of gravitational time dilation, gravitational redshift, and gravitational lensing.
In 1911, Einstein published a subsequent article, "On the Influence of Gravitation on the Propagation of Light," which elaborated upon the 1907 publication. In this work, he calculated the magnitude of light deflection caused by massive celestial bodies. Consequently, this marked the initial opportunity for experimental verification of a theoretical prediction from general relativity.
Gravitational Waves
In 1916, Einstein postulated the existence of gravitational waves, which are ripples in the curvature of spacetime that propagate outward from their source, carrying energy as gravitational radiation. General relativity permits the existence of gravitational waves because its Lorentz invariance implies a finite speed of propagation for gravitational interactions. Conversely, gravitational waves are incompatible with Newtonian theory, which posits an instantaneous propagation of gravitational interactions.
The initial, indirect detection of gravitational waves occurred in the 1970s, stemming from observations of the closely orbiting neutron star binary system, PSR B1913+16. The observed decay in their orbital period was attributed to the emission of gravitational waves. Einstein's prediction received direct confirmation on February 11, 2016, when LIGO researchers announced the first direct observation of gravitational waves, detected on Earth on September 14, 2015, almost a century after their theoretical postulation.
Hole Argument and Entwurf Theory
During the development of general relativity, Einstein encountered conceptual difficulties regarding the theory's gauge invariance. He developed an argument that led him to infer the impossibility of a generally relativistic field theory. Consequently, he ceased seeking fully generally covariant tensor equations, instead pursuing equations invariant solely under general linear transformations.
In June 1913, these investigations culminated in the Entwurf ('draft') theory. True to its designation, it represented a preliminary theoretical outline, characterized by less elegance and greater complexity than general relativity, with its equations of motion requiring supplementary gauge-fixing conditions. Following over two years of intensive research, Einstein recognized the flaw in the hole argument and subsequently abandoned the Entwurf theory in November 1915.
Physical Cosmology
In 1917, Einstein extended the general theory of relativity to encompass the overall structure of the cosmos. His findings indicated that the general field equations inherently predicted a dynamic universe, characterized by either contraction or expansion. Given the contemporary absence of empirical support for a dynamic cosmos, Einstein incorporated a novel term, the cosmological constant, into the field equations to enable the theory to forecast a static universe. These adjusted field equations consequently projected a static universe with closed curvature, aligning with Einstein's interpretation of Mach's principle during that period. This conceptualization subsequently became known as the Einstein World or Einstein's static universe. The publication of this paper is broadly recognized as a pivotal moment in the genesis of modern theoretical cosmology.
Subsequent to Edwin Hubble's 1929 discovery of galactic recession, Einstein renounced his static cosmological model and instead posited two dynamic cosmic models: the Friedmann–Einstein universe in 1931 and the Einstein–de Sitter universe in 1932. Within both of these frameworks, Einstein eliminated the cosmological constant, asserting its inherent theoretical inadequacy.
Numerous biographical accounts of Einstein assert that he later characterized the cosmological constant as his "biggest blunder," a claim purportedly based on a letter George Gamow stated he received from Einstein. However, astrophysicist Mario Livio has expressed skepticism regarding the veracity of this assertion.
In late 2013, a research group spearheaded by Irish physicist Cormac O'Raifeartaigh uncovered indications that Einstein had contemplated a steady-state cosmological model shortly after becoming aware of Hubble's observations concerning galactic recession. Within a previously unexamined manuscript, seemingly composed in early 1931, Einstein investigated an expanding universe model where matter density persisted as constant through continuous matter creation, a mechanism he linked to the cosmological constant. As articulated in the paper, he wrote: "In what follows, I would like to draw attention to a solution to equation (1) that can account for Hubbel's [sic] facts, and in which the density is constant over time [...] If one considers a physically bounded volume, particles of matter will be continually leaving it. For the density to remain constant, new particles of matter must be continually formed in the volume from space."
Consequently, it seems Einstein had conceptualized a steady-state model of the expanding universe several years prior to the work of Hoyle, Bondi, and Gold. Nevertheless, Einstein's steady-state model exhibited a fundamental deficiency, leading to its prompt abandonment.
Energy-Momentum Pseudotensor
Given that general relativity incorporates a dynamic spacetime, precisely identifying conserved energy and momentum presents a significant challenge. While Noether's theorem permits the derivation of these quantities from a Lagrangian exhibiting translational invariance, the principle of general covariance transforms translational invariance into a form of gauge symmetry. Consequently, the energy and momentum derived in general relativity using Noether's prescriptions do not constitute a true tensor.
Einstein contended that this phenomenon arises from a fundamental principle: the gravitational field can be locally eliminated through an appropriate selection of coordinates. He asserted that the non-covariant energy-momentum pseudotensor offered the most accurate representation of energy-momentum distribution within a gravitational field. Although the application of non-covariant entities such as pseudotensors drew criticism from figures like Erwin Schrödinger, Einstein's methodology has found resonance among physicists, notably Lev Landau and Evgeny Lifshitz.
Wormholes
In 1935, Einstein collaborated with Nathan Rosen to develop a wormhole model, frequently referred to as Einstein–Rosen bridges. Their objective was to conceptualize charged elementary particles as solutions to gravitational field equations, consistent with the research agenda presented in their paper, "Do Gravitational Fields Play an Important Role in the Constitution of the Elementary Particles?". These solutions involved connecting Schwarzschild black holes to form a bridge between distinct spacetime regions. Given that these solutions incorporated spacetime curvature absent a physical mass, Einstein and Rosen posited that they might offer a foundational framework for a theory circumventing the concept of point particles. Nevertheless, subsequent investigations revealed the inherent instability of Einstein–Rosen bridges.
Einstein–Cartan Theory
To integrate spinning point particles into general relativity, the affine connection required generalization to incorporate an antisymmetric component, known as torsion. Einstein and Cartan implemented this modification during the 1920s.
Equations of Motion
General relativity reconceptualizes gravitational force as the curvature of spacetime. Consequently, a curved trajectory, such as an orbit, does not arise from a force deflecting an object from a straight path. Instead, it represents the object's free fall through a background intrinsically curved by the presence of other masses. John Archibald Wheeler's widely cited aphorism encapsulates the theory: "Spacetime tells matter how to move; matter tells spacetime how to curve." The Einstein field equations address the latter aspect, establishing the relationship between spacetime curvature and the distribution of matter and energy. Conversely, the geodesic equation describes the former, asserting that objects in free fall traverse paths that are maximally straight within a curved spacetime. Einstein considered this a "fundamental independent assumption" requiring postulation alongside the field equations to complete the theory. Perceiving this as a deficiency in the initial formulation of general relativity, he sought to derive the geodesic equation directly from the field equations. Given the non-linear nature of general relativity's equations, a concentration of pure gravitational fields, such as a black hole, would follow a trajectory determined inherently by the Einstein field equations, rather than by an additional law. Therefore, Einstein posited that the field equations would dictate the geodesic path of a singular solution, like a black hole. While physicists and philosophers frequently reiterate the assertion that the geodesic equation can be derived by applying the field equations to the motion of a gravitational singularity, this proposition continues to be debated.
Old Quantum Theory
Photons and Energy Quanta
In a 1905 publication, Einstein hypothesized that light comprises localized particles, termed quanta. Initially, Einstein's concept of light quanta faced widespread rejection from the physics community, including prominent figures such as Max Planck and Niels Bohr. Universal acceptance of this idea was achieved only in 1919, following Robert Millikan's comprehensive experiments on the photoelectric effect and the subsequent measurement of Compton scattering.
Einstein deduced that every wave with frequency f corresponds to a collection of photons, each possessing energy hf, where h represents the Planck constant. He offered limited further elaboration due to uncertainty regarding the precise relationship between these particles and the wave. Nevertheless, he proposed that this concept could elucidate specific experimental outcomes, particularly the photoelectric effect. Gilbert N. Lewis coined the term photons for light quanta in 1926.
Quantized Atomic Vibrations
In 1907, Einstein introduced a model of matter positing that each atom within a lattice structure functions as an independent harmonic oscillator. According to the Einstein model, individual atoms oscillate autonomously, exhibiting a sequence of equally spaced quantized states for each oscillator. While acknowledging the challenge of determining the precise frequency of actual oscillations, Einstein advanced this theory as a notably lucid illustration of quantum mechanics' capacity to resolve the specific heat anomaly prevalent in classical mechanics. Peter Debye subsequently refined this model.
Bose–Einstein Statistics
In 1924, Einstein received a description of a statistical model from Indian physicist Satyendra Nath Bose, which posited that light could be conceptualized as a gas composed of indistinguishable particles, utilizing a specific counting methodology. Einstein observed that Bose's statistical framework was applicable not only to the hypothesized light particles but also to certain atomic structures, and he subsequently submitted his translation of Bose's manuscript to the journal Journal of Physics. Furthermore, Einstein authored several papers detailing this model and its ramifications, including the prediction of the Bose–Einstein condensate, a state where certain particles manifest at extremely low temperatures. The experimental realization of this condensate did not occur until 1995, when Eric Allin Cornell and Carl Wieman successfully created it using ultra-cooling apparatus developed at the NIST–JILA laboratory, situated at the University of Colorado at Boulder. Currently, Bose–Einstein statistics serve as the descriptive framework for the collective behaviors of any boson assembly. Drafts and preliminary sketches related to this project by Einstein are preserved within the Einstein Archive, housed at the Leiden University library.
Wave–particle duality
Despite his promotion to Technical Examiner Second Class at the patent office in 1906, Einstein maintained his engagement with academic pursuits. By 1908, he had secured a position as a Privatdozent at the University of Bern. In his seminal work, "On the development of our views on the nature and constitution of radiation" ("The Development of our Views on the Composition and Essence of Radiation"), which addressed the quantization of light, and in a preceding paper from 1909, Einstein demonstrated that Max Planck's energy quanta possess distinct momenta and exhibit characteristics akin to independent, point-like particles. This particular publication not only introduced the photon concept but also served as a catalyst for the development of the wave–particle duality principle within quantum mechanics. Einstein interpreted this wave–particle duality inherent in radiation as compelling evidence supporting his belief that physics necessitated a novel, unified theoretical framework.
Zero-point energy
Between 1911 and 1913, Planck undertook a reformulation of his initial 1900 quantum theory, incorporating the concept of zero-point energy into what he termed his "second quantum theory." This concept quickly garnered the interest of Einstein and his collaborator, Otto Stern. Postulating that the energy of rotating diatomic molecules included zero-point energy, they subsequently compared the theoretically derived specific heat of hydrogen gas against empirical data. The theoretical predictions aligned well with the experimental observations. Nevertheless, following the publication of their findings, they swiftly retracted their endorsement, having lost confidence in the validity of the zero-point energy hypothesis.
Stimulated emission
During 1917, while intensely engaged with his research on relativity, Einstein published a pivotal article in Physikalische Zeitschrift. This publication introduced the concept of stimulated emission, a fundamental physical process enabling the operation of masers and lasers. The article demonstrated that the statistical properties governing the absorption and emission of light could only align with Planck's distribution law if the emission of light into a mode containing 'n' photons was statistically augmented relative to emission into an unoccupied mode. This work proved profoundly influential in the subsequent evolution of quantum mechanics, as it represented the inaugural demonstration that the statistics governing atomic transitions adhered to straightforward principles.
Matter waves
Einstein encountered and subsequently endorsed Louis de Broglie's theories, which initially met with considerable skepticism. In a significant publication from the same period, Einstein noted that de Broglie waves possessed the explanatory power for the quantization rules established by Bohr and Sommerfeld. This particular paper subsequently served as an inspiration for Schrödinger's research conducted in 1926.
Quantum mechanics
Einstein's objections to quantum mechanics
Einstein significantly contributed to the advancement of quantum theory, commencing with his seminal 1905 publication on the photoelectric effect. Nevertheless, he expressed dissatisfaction with the trajectory of modern quantum mechanics following 1925, notwithstanding its widespread acceptance among his peers. He harbored skepticism regarding the intrinsic randomness of quantum mechanics, positing instead that it might be a manifestation of underlying determinism, famously asserting that God "is not playing at dice." Throughout the remainder of his life, he consistently contended that quantum mechanics remained an incomplete theory.
Bohr versus Einstein
The Bohr–Einstein debates comprised a series of public disagreements concerning quantum mechanics, primarily between its co-founders, Albert Einstein and Niels Bohr. These discussions are historically significant due to their profound impact on the philosophy of science and subsequently influenced various interpretations of quantum mechanics.
Einstein–Podolsky–Rosen Paradox
Albert Einstein never fully embraced the tenets of quantum mechanics. Although he acknowledged its predictive accuracy, Einstein maintained that a more fundamental description of natural phenomena was attainable. He advanced numerous arguments to support this perspective over time, with his preferred one originating from a 1930 debate with Bohr. Einstein proposed a thought experiment involving two objects that interact and subsequently separate by a considerable distance. In quantum mechanics, these two objects are described by a mathematical entity termed a wavefunction. Given the initial wavefunction describing the two objects prior to their interaction, the Schrödinger equation determines their wavefunction following the interaction. However, due to the phenomenon later designated as quantum entanglement, a measurement performed on one object would instantaneously alter the wavefunction of the other, irrespective of their spatial separation. Furthermore, the specific type of measurement chosen for the first object would influence the resulting wavefunction for the second. Einstein contended that no influence could propagate instantaneously between the first and second objects. He argued that the foundational principle of physics, distinguishing one entity from another, would be undermined by such instantaneous influences. Consequently, Einstein concluded that since the genuine "physical condition" of the second object could not be instantly modified by an action on the first, the wavefunction must represent merely an incomplete description, rather than the true physical state.
A more widely recognized iteration of this argument emerged in 1935, when Einstein, in collaboration with Boris Podolsky and Nathan Rosen, published a seminal paper outlining what subsequently became known as the EPR paradox. This thought experiment posits two particles interacting to produce an entangled wavefunction. Subsequently, regardless of the spatial separation between these particles, a precise measurement of one particle's position would enable a perfect prediction of the other particle's position. Similarly, an accurate momentum measurement of one particle would yield an equally precise prediction for the momentum of the other, without any disturbance to the latter. The authors contended that no action on the first particle could instantaneously influence the second, as this would necessitate superluminal information transfer, a phenomenon prohibited by the theory of relativity. They introduced a principle, subsequently termed the "EPR criterion of reality," which asserts: "If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of a physical quantity, then there exists an element of reality corresponding to that quantity." Based on this criterion, they inferred that the second particle must possess definite values for both position and momentum even before either quantity is measured. However, quantum mechanics regards these two observables as incompatible, thereby precluding the assignment of simultaneous values for both to any given system. Consequently, Einstein, Podolsky, and Rosen concluded that quantum theory offers an incomplete description of reality.
In 1964, John Stewart Bell significantly advanced the analysis of quantum entanglement. He posited that independent measurements on two spatially separated entangled particles, under the premise that outcomes are determined by hidden variables inherent to each particle, would impose a specific mathematical constraint on the correlation between these measurement results. This constraint subsequently became known as a Bell inequality. Bell further demonstrated that quantum physics predicts correlations that contravene this inequality. Therefore, for hidden variables to account for quantum physics' predictions, they must exhibit "nonlocality," implying an instantaneous interaction between the two particles regardless of their spatial separation. Bell contended that since a hidden-variable explanation of quantum phenomena necessitates nonlocality, the Einstein-Podolsky-Rosen (EPR) paradox was "resolved in the way which Einstein would have liked least."
Notwithstanding this, and despite Einstein's personal assessment of the EPR paper's argument as excessively complex, it emerged as one of the most influential articles published in Physical Review. It is regarded as a foundational element in the evolution of quantum information theory.
Unified Field Theory
Building upon the success of his general theory of relativity, Einstein pursued a more ambitious geometrical framework aiming to integrate gravitation and electromagnetism as manifestations of a singular underlying entity. In 1950, he articulated his unified field theory within a Scientific American article titled "On the Generalized Theory of Gravitation." While his endeavor to uncover the fundamental laws of nature garnered acclaim, it did not achieve success; a notable deficiency of his model was its inability to incorporate the strong and weak nuclear forces, both of which remained poorly understood until decades after his demise. Although the prevailing scientific consensus now suggests that Einstein's methodology for unifying physics was flawed, the overarching objective of a theory of everything continues to inspire subsequent generations of physicists.
Other Investigations
Einstein undertook additional investigations that ultimately proved unsuccessful and were subsequently discontinued. These inquiries encompassed topics such as force, superconductivity, and various other research areas.
Collaboration with Other Scientists
Beyond his long-term collaborators such as Leopold Infeld, Nathan Rosen, and Peter Bergmann, Einstein also engaged in singular collaborative efforts with diverse scientists.
Einstein–de Haas Experiment
In 1908, Owen Willans Richardson theorized that an alteration in the magnetic moment of a free body would induce its rotation. This phenomenon, stemming from the conservation of angular momentum, is sufficiently pronounced to be detectable in ferromagnetic substances. Einstein and Wander Johannes de Haas co-authored two papers in 1915, asserting the initial experimental observation of this effect. Such measurements illustrate that magnetization arises from the alignment (polarization) of electron angular momenta within the material along the magnetization axis. Furthermore, these measurements enable the differentiation between the two components contributing to magnetization: those linked to electron spin and those associated with orbital motion. The Einstein-de Haas experiment stands as the sole experimental endeavor conceptualized, executed, and published personally by Albert Einstein.
A complete original set of the Einstein-de Haas experimental apparatus was bequeathed by Geertruida de Haas-Lorentz, de Haas's wife and Lorentz's daughter, to the Ampère Museum in Lyon, France, in 1961, where it is presently exhibited. It had been misplaced within the museum's collection and was subsequently rediscovered in 2023.
Einstein as an Inventor
In 1926, Einstein and his former student Leó Szilárd jointly invented, and subsequently patented in 1930, the Einstein refrigerator. This absorption refrigerator was considered groundbreaking at the time due to its lack of moving components and its reliance solely on heat as an energy input. On November 11, 1930, U.S. patent 1,781,541 was granted to Einstein and Leó Szilárd for this refrigeration device. Although their invention did not immediately enter commercial production, the most promising of their patents were acquired by the Swedish corporation Electrolux.
Einstein also devised an electromagnetic pump, a sound reproduction apparatus, and various other domestic appliances.
Legacy
Non-scientific
During his travels, Einstein maintained daily correspondence with his wife, Elsa, and his adopted stepdaughters, Margot and Ilse. This collection of letters was subsequently bequeathed to the Hebrew University of Jerusalem as part of his papers. Margot Einstein authorized the public release of these personal letters, stipulating that access be granted only two decades after her passing in 1986. According to Barbara Wolff from the Hebrew University's Albert Einstein Archives, approximately 3,500 pages of private correspondence, dating from 1912 to 1955, exist within the collection.
During the last four years of his life, Einstein actively participated in the founding of the Albert Einstein College of Medicine, located in New York City.
The Albert Einstein Memorial was inaugurated in 1979, coinciding with the centenary of Einstein's birth, and is situated outside the National Academy of Sciences building in Washington, D.C. Robert Berks was the sculptor responsible for its creation. The sculpture depicts Einstein holding a document inscribed with three of his seminal equations: those pertaining to the photoelectric effect, general relativity, and mass-energy equivalence.
In 2015, Einstein's right of publicity became the subject of litigation within a federal district court in California. While the court initially determined that this right had lapsed, the ruling faced an immediate appeal, leading to the subsequent vacating of the decision in its entirety. The fundamental claims between the involved parties in the aforementioned lawsuit were eventually resolved through settlement. Consequently, the right remains enforceable, with the Hebrew University of Jerusalem serving as its sole authorized representative. Corbis, which succeeded The Roger Richman Agency, manages the licensing of Einstein's name and related imagery on behalf of the university.
Mount Einstein, located in Alaska's Chugach Mountains, received its designation in 1955. A separate peak, also named Mount Einstein, situated in New Zealand's Paparoa Range, was named in his honor in 1970 by the Department of Scientific and Industrial Research.
In 1999, Time magazine designated Einstein as its Person of the Century.
Scientific Recognition
A 1999 survey among the top 100 physicists identified Einstein as the "greatest physicist ever"; however, a concurrent survey of general physicists ranked Isaac Newton first, with Einstein placing second.
Physicist Lev Landau developed a logarithmic scale, ranging from 0 to 5, to assess productivity and genius among physicists. On this scale, Newton achieved the highest possible ranking of 0, followed by Einstein at 0.5. Prominent figures in quantum mechanics, including Paul Dirac, Niels Bohr, and Werner Heisenberg, were assigned a ranking of 1, while Landau himself was rated a 2.
In his work The Scientific 100, science writer John G. Simmons positioned Einstein as second only to Newton. This qualitative assessment prioritized scientists based on their cumulative influence, with Simmons asserting that Einstein's contributions "forms the source of twentieth-century physics."
Physicist Eugene Wigner observed that although John von Neumann possessed the most rapid and incisive intellect he had encountered, Einstein's mind was demonstrably more profound and innovative, as articulated by Wigner:
But Einstein's understanding was deeper than even Jancsi von Neumann's. His mind was both more penetrating and more original than von Neumann's. And that is a very remarkable statement. Einstein took an extraordinary pleasure in invention. Two of his greatest inventions are the Special and General Theories of Relativity; and for all of Jancsi's brilliance, he never produced anything so original. No modern physicist has.
The International Union of Pure and Applied Physics designated 2005 as the "World Year of Physics," also referred to as "Einstein Year," commemorating Einstein's "miracle year" of 1905. Concurrently, the United Nations proclaimed 2005 the "International Year of Physics."
In Popular Culture
Following the empirical confirmation of his general theory of relativity in 1919, Einstein rapidly ascended to the status of a prominent scientific celebrity. Despite a general lack of public comprehension regarding his scientific contributions, he garnered widespread recognition and admiration. A pre-World War II vignette in The New Yorker's "The Talk of the Town" feature illustrated Einstein's pervasive fame in America, noting that he was frequently approached in public by individuals requesting explanations of "that theory." To manage these unsolicited inquiries, he eventually adopted a strategy of feigning mistaken identity, responding with phrases such as, "Pardon me, sorry! Always I am mistaken for Professor Einstein."
Einstein has served as the subject or inspiration for numerous novels, films, plays, and musical compositions. He is frequently portrayed as an absent-minded professor, with his distinctive expressive face and hairstyle widely imitated and exaggerated. Frederic Golden of Time magazine characterized Einstein as "a cartoonist's dream come true." His intellectual accomplishments and originality have rendered Einstein broadly synonymous with genius.
Many popular quotations are frequently misattributed to him.
Awards and Honors
Einstein received numerous awards and honors, notably the 1921 Nobel Prize in Physics, awarded in 1922 "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect." As none of the 1921 nominations fulfilled Alfred Nobel's criteria, the prize for that year was deferred and subsequently presented to Einstein in 1922.
Einsteinium, a synthetic chemical element, was named in his honor in 1955, several months after his death.
Publications
Scientific
- Popular
Popular
Political
- Einstein, Albert; et al. (December 4, 1948). "To the editors of The New York Times". The New York Times.Einstein, Albert (May 1949). Sweezy, Paul; Huberman, Leo (eds.). "Why Socialism?". Monthly Review. §34§ (1): 9–15. doi:10.14452/MR-001-01-1949-05_3.—————— (May 2009) [May 1949]. "Why Socialism? (Reprise)". Monthly Review. New York: Monthly Review Foundation.Notes
Notes
References
Works Cited
- Works by Albert Einstein at Project Gutenberg
- Works by Albert Einstein at LibriVox (public domain audiobooks)
- Archival materials collections
- Archival materials collections
- Albert Einstein Historical Letters, Documents & Papers from Shapell Manuscript Foundation
- The Albert Einstein Archives at The Hebrew University of Jerusalem
- Digital collections
- Newspaper clippings about Albert Einstein in the 20th Century Press Archives of the ZBW
- Albert – The Digital Repository of the IAS, which contains many digitized original documents and photographs