Albert Einstein

Albert Einstein
Born	Albert Einstein 14 3, 1879
Birthplace	Ulm, Kingdom of Württemberg, German Empire
Died	Template:Death date and age Princeton, New Jersey, United States
Nationality	German (until 1896), Swiss (from 1901), American (from 1940)
Occupation	Theoretical physicist
Known for	General relativity, special relativity, photoelectric effect, mass–energy equivalence (E = mc²)
Education	University of Zurich (PhD, 1905)
Spouse(s)	Template:Plainlist
Awards	Nobel Prize in Physics (1921), Matteucci Medal (1921), Copley Medal (1925)

Albert Einstein (14 March 1879 – 18 April 1955) was a German-born theoretical physicist who fundamentally reshaped humanity's understanding of space, time, energy, and gravity. Born in Ulm, in the Kingdom of Württemberg within the German Empire, Einstein spent his formative years in Munich and later Switzerland before embarking on a career that would produce some of the most consequential ideas in the history of science. He is best known for developing the special and general theories of relativity, for his mass–energy equivalence formula E = mc², and for his explanation of the photoelectric effect, for which he received the 1921 Nobel Prize in Physics. Beyond relativity, Einstein made foundational contributions to quantum mechanics, statistical mechanics, and cosmology, introducing concepts such as stimulated emission, which later became the theoretical basis for the laser. A man of deep moral convictions, he fled Nazi Germany in 1933, settled permanently in the United States, and spent his final decades at the Institute for Advanced Study in Princeton, New Jersey, where he continued to pursue a unified field theory until his death in 1955. His name has become synonymous with scientific genius, and his work continues to be tested and validated by modern experiments, including recent efforts using advanced atomic clocks to probe the predictions of general relativity with unprecedented accuracy.

Early Life

Albert Einstein was born on 14 March 1879 in Ulm, in the Kingdom of Württemberg, part of the German Empire. His father, Hermann Einstein, was a salesman and engineer, and his mother was Pauline Einstein (née Koch). The family was Ashkenazi Jewish. In 1880, the family moved to Munich, where Hermann Einstein and his brother Jakob founded Elektrotechnische Fabrik J. Einstein & Cie, a company that manufactured electrical equipment based on direct current.

Einstein showed an early aptitude for mathematics and science. According to accounts of his childhood, a compass given to him by his father at the age of five made a lasting impression; the invisible forces that directed the needle sparked a sense of wonder that would persist throughout his life. He attended a Catholic elementary school in Munich from age five to eight, and then transferred to the Luitpold Gymnasium (later renamed the Albert Einstein Gymnasium), where he received advanced primary and secondary education. Einstein excelled in mathematics and physics but reportedly chafed at the rote-learning style of instruction prevalent in German schools at the time.

In 1894, when the family business failed, the Einsteins moved to Italy—first to Milan and then to Pavia. Albert, then fifteen, was left behind to finish his education in Munich, but he soon left the gymnasium, either by his own initiative or by expulsion (accounts vary), and joined his family in Italy. He renounced his German citizenship in 1896 to avoid military service and remained stateless for several years.

In 1895, at the age of sixteen, Einstein sat the entrance examination for the Swiss Federal Polytechnic School (later known as ETH Zurich) in Zurich. Although he performed exceptionally in mathematics and physics, he did not pass the general portion of the exam, and the polytechnic's principal recommended that he complete his secondary education first. Einstein enrolled in the Argovian cantonal school (Gymnasium) in Aarau, Switzerland, from which he graduated in 1896. During his time in Aarau, Einstein reportedly wrote his first scientific essay, an exploration of the state of the ether in a magnetic field.

Education

In 1897, at the age of seventeen, Einstein enrolled in the four-year mathematics and physics teaching diploma program at the Swiss Federal Polytechnic School in Zurich. His classmates included Marcel Grossmann, who would later become an important mathematical collaborator, and Mileva Marić, a Serbian physics student who would become his first wife. Einstein was known for attending lectures irregularly, preferring instead to study independently, often from the latest works in physics. He relied on Grossmann's meticulous lecture notes to pass his examinations.

Einstein graduated in 1900 with a diploma in mathematics and physics. He acquired Swiss citizenship in 1901, which he retained for the remainder of his life. Unable to secure an academic position immediately after graduation, he took on temporary teaching and tutoring posts. In 1902, with the help of Marcel Grossmann's father, Einstein obtained a position as a technical assistant examiner at the Swiss Patent Office in Bern, where he evaluated patent applications for electromagnetic devices.

While working at the patent office, Einstein pursued his doctoral research. In 1905, he submitted his doctoral dissertation, "A New Determination of Molecular Dimensions," to the University of Zurich, which accepted it and awarded him a PhD.

Career

Annus Mirabilis (1905)

The year 1905 is often described as Einstein's annus mirabilis—his miracle year. While still employed as a patent examiner in Bern, he published four groundbreaking papers in the journal Annalen der Physik that transformed modern physics.

The first paper, on the photoelectric effect, proposed that light is composed of discrete energy quanta (later called photons). This was a radical departure from the classical wave theory of light and provided key evidence for the emerging quantum theory. Einstein postulated that when light strikes a metal surface, the energy of individual light quanta is transferred to electrons, which are ejected if the energy exceeds a certain threshold. This work was the primary basis for his receiving the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect."

The second paper provided an explanation for Brownian motion—the apparently random movement of particles suspended in a fluid. Einstein demonstrated that this motion could be explained by the kinetic molecular theory, providing strong empirical evidence for the existence of atoms and molecules at a time when their reality was still debated by some scientists.

The third paper introduced the special theory of relativity, which reconciled Maxwell's equations of electromagnetism with the laws of mechanics by proposing two postulates: that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum is constant regardless of the motion of the observer or the light source. This theory dispensed with the concept of the luminiferous ether and introduced radical new ideas about the nature of space and time, including the concept that simultaneity is relative.

The fourth paper, a consequence of special relativity, demonstrated the equivalence of mass and energy, encapsulated in the equation E = mc². This formula showed that a small amount of mass could be converted into a large amount of energy, a principle that would later underpin nuclear energy and nuclear weapons.

General Relativity (1907–1915)

After his breakthrough in 1905, Einstein gradually rose through the academic ranks. He was appointed lecturer at the University of Bern in 1908, became an associate professor at the University of Zurich in 1909, and then moved to the German Charles-Ferdinand University in Prague in 1911 as a full professor. He returned to the Swiss Federal Polytechnic in Zurich in 1912 before being appointed to the Prussian Academy of Sciences and the Humboldt University of Berlin in 1914. In Berlin, he also became director of the Kaiser Wilhelm Institute for Physics in 1917.

Throughout this period, Einstein was working toward a generalization of his special theory of relativity to include gravity. Beginning around 1907, he developed the equivalence principle—the idea that gravitational acceleration and the acceleration of a reference frame are physically indistinguishable. This insight led him, after eight years of intensive mathematical work (often in collaboration with Marcel Grossmann, who introduced him to the Riemannian geometry and tensor calculus necessary for the task), to the general theory of relativity, which he completed in November 1915.

General relativity replaced Newton's law of universal gravitation with a geometric theory in which gravity is described as the curvature of spacetime caused by mass and energy. The field equations Einstein published predicted several phenomena that were subsequently confirmed by observation, including the precession of the perihelion of Mercury, the deflection of light by massive objects (confirmed during the solar eclipse of 1919), and gravitational redshift.

In 1916, Einstein published a paper laying out the broader implications of general relativity for cosmology, introducing the cosmological constant in an attempt to model a static universe. This paper is regarded as the first step in the field of modern theoretical cosmology. Einstein later called the cosmological constant his "greatest mistake" after Edwin Hubble's observations in 1929 demonstrated that the universe was expanding, though the constant was revived in the late 20th century in the context of dark energy.

Quantum Theory and Statistical Mechanics

In addition to his work on relativity, Einstein made major contributions to quantum theory and statistical mechanics during the middle part of his career. In 1917, he published a paper introducing the concepts of spontaneous emission and stimulated emission of radiation. The concept of stimulated emission—whereby an incoming photon causes an excited atom to emit an additional photon of the same frequency and phase—later became the core mechanism behind the laser and maser, technologies that would not be developed until decades after Einstein's theoretical groundwork.

Einstein's work on the quantum physics of radiation, including his development of Bose–Einstein statistics in collaboration with Indian physicist Satyendra Nath Bose in the mid-1920s, predicted the existence of Bose–Einstein condensates—a state of matter in which particles cooled to near absolute zero begin to occupy the same quantum state. This prediction was experimentally confirmed in 1995.

Despite his foundational contributions to quantum theory, Einstein became increasingly skeptical of its interpretation, particularly the Copenhagen interpretation championed by Niels Bohr and others. He objected to the probabilistic nature of quantum mechanics, famously declaring (in a letter to Max Born) that "God does not play dice." The Bohr–Einstein debates, which took place primarily at the Solvay Conferences in the late 1920s and early 1930s, became one of the most significant intellectual exchanges in the history of physics. Einstein proposed several thought experiments, including the EPR paradox (1935, with Boris Podolsky and Nathan Rosen), to argue that quantum mechanics was incomplete. This debate continued to influence the development of quantum physics long after Einstein's death, notably through Bell's theorem and subsequent experimental tests of quantum entanglement.

Move to the United States (1933–1955)

In 1933, while Einstein was visiting the United States, Adolf Hitler came to power in Germany. The Nazi regime's persecution of Jews and its broader assault on academic freedom made a return impossible. Einstein's property in Germany was confiscated, and he was stripped of his German citizenship. He settled in the United States and accepted a position at the newly established Institute for Advanced Study in Princeton, New Jersey, where he would remain for the rest of his life.

Einstein was granted American citizenship in 1940. On the eve of World War II, in August 1939, he signed a letter—drafted primarily by physicist Leó Szilárd—addressed to President Franklin D. Roosevelt alerting him to the possibility that Germany might develop nuclear weapons and recommending that the United States begin its own nuclear research. This letter is widely credited with catalyzing the creation of the Manhattan Project, although Einstein himself did not participate directly in the project due to security concerns about his pacifist and left-leaning political associations.

During his years in Princeton, Einstein focused primarily on his search for a unified field theory—an attempt to unify the gravitational and electromagnetic forces within a single theoretical framework. Despite decades of effort, he did not succeed in this goal, and the work was considered by many contemporaries to be a blind alley. Nevertheless, the pursuit of unification remains a central objective of theoretical physics, with modern approaches such as string theory and loop quantum gravity continuing in the spirit of Einstein's quest.

Einstein also remained politically active during his American years. He was an outspoken advocate for civil rights, befriending prominent African American leaders. He supported Zionism and was offered the presidency of Israel in 1952 following the death of Chaim Weizmann, but declined the offer, stating that he lacked the natural aptitude and experience for dealing with people. He also wrote on political and social topics, including a 1949 essay titled "Why Socialism?" published in the inaugural issue of Monthly Review.

Personal Life

Einstein married Mileva Marić, a fellow physics student whom he had met at the Swiss Federal Polytechnic, in January 1903. The couple had a daughter, Lieserl (born in 1902, whose fate remains uncertain—she may have been given up for adoption or may have died in infancy), and two sons: Hans Albert (born 1904) and Eduard (born 1910). The marriage was strained for many years, partly due to Einstein's frequent absences and his relationship with his cousin Elsa Löwenthal. Albert and Mileva divorced in February 1919, with a settlement that included the Nobel Prize money Einstein anticipated receiving.

Einstein married Elsa Löwenthal (née Einstein) in June 1919. Elsa had two daughters from a previous marriage. The couple lived together in Berlin until their emigration to the United States in 1933. Elsa died in December 1936 in Princeton.

Einstein was known for his unconventional appearance and personal habits. He often eschewed socks, and in later years adopted a deliberately simple wardrobe. He was an accomplished amateur violinist with a lifelong love of music, particularly the works of Mozart and Bach. He also enjoyed sailing, though by his own admission he was not particularly skilled at it.

Einstein's political views leaned toward socialism and pacifism. He was a member of several peace organizations and spoke publicly against the development of nuclear weapons after World War II, most notably as a co-signatory of the Russell–Einstein Manifesto in 1955, which called for the reduction of nuclear arsenals.

Einstein died on 18 April 1955 at Princeton Hospital from an abdominal aortic aneurysm. He had refused surgery, reportedly saying, "I want to go when I want. It is tasteless to prolong life artificially." His body was cremated and his ashes scattered at an undisclosed location, although his brain was removed during autopsy by pathologist Thomas Stoltz Harvey for scientific study.

Recognition

Einstein received 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." The prize recognized his 1905 paper rather than his work on relativity, which remained controversial among some members of the Nobel Committee at the time.

Beyond the Nobel Prize, Einstein received numerous other honors during his lifetime. He was awarded the Matteucci Medal in 1921, the Copley Medal of the Royal Society in 1925, the Max Planck Medal of the German Physical Society in 1929, and the Franklin Medal of the Franklin Institute in 1935. He was elected a foreign member of the Royal Society in 1921 and a member of numerous other national academies of science.

In 1999, Time magazine named Einstein the "Person of the Century," reflecting his stature not only within the scientific community but in the broader culture. The element einsteinium, discovered in 1952, was named in his honor, as was the unit of measurement called the einstein, used in photochemistry. The Albert Einstein Medal has been awarded by the Albert Einstein Society in Bern since 1979 for outstanding scientific achievements related to Einstein's work.

His name and legacy also persist through educational programs. The Albert Einstein Distinguished Educator Fellowship Program, sponsored by the United States Department of Energy, places STEM teachers in federal agencies, including the Library of Congress.

Legacy

Einstein's contributions to physics reshaped the scientific understanding of the universe. The general theory of relativity provided the framework for modern cosmology, including the study of black holes, gravitational waves, and the expansion of the universe. In 2016, the LIGO collaboration announced the first direct detection of gravitational waves—ripples in spacetime predicted by Einstein a century earlier—generated by the merger of two black holes. This discovery, which earned the 2017 Nobel Prize in Physics for LIGO's principal investigators, represented a dramatic confirmation of general relativity.

The theoretical concept of Einstein–Rosen bridges (wormholes), derived from the equations of general relativity, continues to be a subject of active research. Recent theoretical work has explored whether such structures may reflect a two-directional structure of time and provide insights into information preservation and pre–Big Bang cosmology.

Einstein's predictions continue to be tested with increasing precision. In 2026, scientists at the National Institute of Standards and Technology (NIST) reported using the world's most accurate atomic clocks to probe the predictions of general relativity regarding the relationship between gravity and the passage of time, with potential applications in geodesy, navigation, and fundamental physics.

Beyond physics, Einstein's cultural impact has been profound. His image—the wild white hair, the expressive face—has become an icon of intellectual achievement. His aphorisms on imagination, curiosity, and perseverance are frequently cited in educational and motivational contexts. His political activism, including his advocacy for civil rights, pacifism, and international cooperation, established a model for the scientist as a public intellectual.

Einstein's involvement in the founding of the Hebrew University of Jerusalem in 1925, to which he bequeathed his personal archives and intellectual property, ensured that his legacy would be preserved and studied by future generations. A century after his involvement, the university continues to maintain and expand upon his scholarly heritage.

His quest for a unified field theory, though unfulfilled in his lifetime, foreshadowed the direction of much of late 20th- and early 21st-century theoretical physics. The ongoing search for a theory of everything—a framework that unites general relativity with quantum mechanics—continues to be shaped by the questions Einstein first posed.