# Albert Einstein

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Albert Einstein (Ulm, March 14, 1879 – Princeton, April 18, 1955) was a German-born theoretical physicist. Popularly regarded as the most important scientist of the 20th century, he formulated the special and general theories of relativity, and made important contributions to both quantum theory and statistical mechanics. While best known for the Theory of Relativity (and specifically mass-energy equivalence, E = mc²), he was awarded the 1921 Nobel Prize for Physics for his explanation of the photoelectric effect in 1905 (his "wonderful year" or "miraculous year") and "for his services to Theoretical Physics".

His world fame in physics began in the early 20th century when indisputable evidence supporting his ideas became available. Analysis of the May-1919 British solar-eclipse expeditions confirmed that light rays from distant stars were deflected by the Sun's gravitation, just as predicted by the field equations of general relativity. Once the results of the analysis were accepted, The London Times ran the headline (on November 7, 1919): "Revolution in science – New theory of the Universe – Newtonian ideas overthrown" and Albert Einstein became a global celebrity, an unusual designation for a scientist. In popular culture, the name "Einstein" has become synonymous with great intelligence and genius.

## Biography

Einstein was born on March 14, 1879 in the city of Ulm in Württemberg, Germany, about 100 km east of Stuttgart. His father was Hermann Einstein, a salesman who later ran an electrochemical works, and his mother was Pauline, née Koch. They were married in Stuttgart-Bad Cannstatt. Albert's family members were all non-observant Jews and he attended a Catholic elementary school. At the insistence of his mother, he was given violin lessons. Though he initially disliked the lessons, and eventually discontinued them, he would later take great solace in Mozart's violin sonatas.

When Einstein was five, his father showed him a small pocket compass, and Einstein realized that something in "empty" space acted upon the needle; he would later describe the experience as one of the most revelatory events of his life. He built models and mechanical devices for fun and showed great mathematical ability early on.

In 1889, a medical student named Max Talmud (later: Talmey), who visited the Einsteins on Thursday nights for 6 years,[1] introduced Einstein to key science and philosophy texts, including Kant's Critique of Pure Reason. Two of his uncles would further foster his intellectual interests during his late childhood and early adolescence by recommending and providing books on science, mathematics and philosophy.

Einstein attended the Luitpold Gymnasium, where he received a relatively progressive education. With the help of Max Talmey he began to learn mathematics around age twelve; in 1891, he taught himself Euclidean plane geometry from a school booklet and began to study calculus soon afterwards.[2] Einstein realized the power of axiomatic deductive reasoning from the book of Euclid's Elements, which he called the "holy little geometry book" [1] (given by Talmey [Talmud]). While at the Gymnasium, Einstein clashed with authority and resented the school regimen, believing that the spirit of learning and creative thought were lost in such endeavors as strict memorization.

In 1894, following the failure of Hermann Einstein's electrochemical business, the Einsteins moved from Munich to Pavia, a city in Italy near Milan. Einstein's first scientific work, called "The Investigation of the State of Aether in Magnetic Fields", was written contemporaneously. Albert remained behind in Munich lodgings to finish school, completing only one term before leaving the gymnasium in the spring of 1895 to rejoin his family in Pavia. He quit a year and a half prior to final examinations without telling his parents, convincing the school to let him go with a medical note from a friendly doctor, but this meant that he had no secondary-school certificate.[3] That year, at the age of 16, he conceived the thought experiment known as "Albert Einstein's mirror". After gazing into a mirror, he examined what would happen to his image if he were moving at the speed of light; his conclusion, that the speed of light is independent of the observer, would later become one of the two postulates of special relativity.

Despite being some two years below the normal age of entry, in 1895 Einstein was granted special dispensation to take the entrance examinations for the Federal Polytechnic Institute in Zurich, today the ETH Zurich. He excelled in the mathematics and science part of examinations, but failed to achieve the required level in other subjects.[4] In 1895-1896 he attended the cantonal school in Aarau, Switzerland to finish his secondary education, and it became clear that he was not going to be an electrical engineer as his father intended for him. There, he studied the seldom-taught Maxwell's electromagnetic theory and received his diploma in September 1896. During this time, he lodged with Professor Jost Winteler's family and became enamoured with Marie, their daughter and his first sweetheart. Einstein's sister, Maja, who was perhaps his closest confidant, was to later marry their son, Paul, and his friend, Michele Besso, married their other daughter, Anna.[5] Einstein subsequently enrolled at the Federal Polytechnic Institute for the mathematics and physics teaching course in October 1900 and moved to Zurich, while Marie moved to Olsberg, Switzerland for a teaching post. The same year, he renounced his Württemberg citizenship and became stateless.

In the spring of 1896, the Serbian Mileva Marić started initially as a medical student at the University of Zurich, but after a term switched to the Federal Polytechnic Institute to study, as the only woman that year, for the same teaching diploma as Einstein. Marić's relationship with Einstein developed into romance over the next few years.

In 1900, Einstein was granted a teaching diploma by the Federal Polytechnic Institute, while Marić failed the final examination, with a very low grade in the mathematics component, theory of functions.[6] The following year, while pregnant with their out-of-wedlock daughter Liserl, she failed a second time without improving her grade.[7] Lieserl was born in January 1902. Her fate is unknown; some think she died in infancy, while others think she was given out for adoption. Einstein and Marić were married in January 1903.

Meanwhile, in 1901, Einstein published his first paper, on capillary forces, titled "Folgerungen aus den Capillaritätserscheinungen", which translated is "Consequences of the observations of capillarity phenomena" (found in "Annalen der Physik" volume 4, page 513). In it, he tried to unify the laws of physics, an attempt he would continually make throughout his life. Through his friend Michele Besso, an engineer, Einstein was presented with the works of Ernst Mach, and would later consider him "the best sounding board in Europe" for physical ideas. During this time, Einstein discussed his scientific interests with a group of close friends, including Besso and Marić. The men referred to themselves as the "Olympia Academy".

### Works and doctorate

Einstein could not find a teaching post upon graduation, mostly because his brashness as a young man had apparently irritated most of his professors. The father of a classmate helped him obtain employment as a technical assistant examiner at the Swiss Patent Office[8] in 1902. There, Einstein judged the worth of inventors' patent applications for devices that required a knowledge of physics to understand — in particular he was chiefly charged to evaluate patents relating to electromagnetic devices.[9] He also learned how to discern the essence of applications despite sometimes poor descriptions, and was taught by the director how "to express [him]self correctly". He occasionally rectified their design errors while evaluating the practicality of their work.

Einstein's marriage to Marić was initially successful, and a second child, Hans Albert, was born on May 14, 1904. Marić's support and encouragement was of invaluable help during the early period of Einstein's scientific career, but historians of physics remain sceptical of claims that she made substantial contributions to his work.[10]

Abram Joffe, a Soviet physicist who had met Einstein, wrote in an obituary of him: "For physics, and especially for the physics of my generation... Einstein's entrance into the arena of science was unforgettable... The author of [the papers of 1905] was... a bureaucrat at the Patent Office in Bern, Einstein-Marity...".[11] This has recently been taken as evidence of a collaborative relationship. However, according to Alberto A. Martínez,[12] now at the University of Texas, Joffe only ascribed authorship to Einstein, as he believed that it was a Swiss custom at the time to append the spouse's last name to the husband's name.[13]

In 1903, Einstein's position at the Swiss Patent Office had been made permanent, though he was passed over for promotion until he had "fully mastered machine technology".[14] He obtained his doctorate under Alfred Kleiner at the University of Zurich after submitting his thesis "A new determination of molecular dimensions" ("Eine neue Bestimmung der Moleküldimensionen") in 1905.

#### Annus Mirabilis papers

During 1905, in his spare time, he wrote four articles that participated in the foundation of modern physics, without much scientific literature to which he could refer or many scientific colleagues with whom he could discuss the theories. Most physicists agree that three of those papers (on Brownian motion, the photoelectric effect, and special relativity) deserved Nobel Prizes. Only the paper on the photoelectric effect would be mentioned by the Nobel committee in the award; at the time of the award, it had the most unchallenged experimental evidence behind it, although the Nobel committee expressed the opinion that Einstein's other work would be confirmed in due course.

Some might regard the award for the photoelectric effect ironic, not only because Einstein is far better-known for relativity, but also because the photoelectric effect is a quantum phenomenon, and Einstein became somewhat disenchanted with the path quantum theory would take.

Einstein submitted this series of papers to the "Annalen der Physik". They are commonly referred to as the "Annus Mirabilis Papers" (from Annus mirabilis, Latin for 'year of wonders'). The International Union of Pure and Applied Physics (IUPAP) commemorated the 100th year of the publication of Einstein's extensive work in 1905 as the 'World Year of Physics 2005'.

The first paper, named "On a Heuristic Viewpoint Concerning the Production and Transformation of Light", ("Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt") was specifically cited for his Nobel Prize. In this paper, Einstein extends Planck's hypothesis (${\displaystyle E=h\nu }$) of discrete energy elements to his own hypothesis that electromagnetic energy is absorbed or emitted by matter in quanta of ${\displaystyle h\nu }$ (where h is Planck's constant and ${\displaystyle \nu }$ is the frequency of the light), proposing a new law

${\displaystyle E_{\max }=h\nu -P\,}$

to account for the photoelectric effect, as well as other properties of photoluminescence and photoionization. In later papers, Einstein used this law to describe the Volta effect (1906), the production of secondary cathode rays (1909) and the high-frequency limit of Bremsstrahlung (1911). Einstein's key contribution is his assertion that energy quantization is a general, intrinsic property of light, rather than a particular constraint of the interaction between matter and light, as Planck believed. Another, often overlooked result of this paper was Einstein's excellent estimate (6.17 ${\displaystyle \times }$ 1023) of Avogadro's number (6.02 ${\displaystyle \times }$ 1023). However, Einstein does not propose that light is a particle in this paper; the "photon" concept was not proposed until 1909 (see below).

His second article in 1905, named "On the Motion—Required by the Molecular Kinetic Theory of Heat—of Small Particles Suspended in a Stationary Liquid", ("Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen") covered his study of Brownian motion, and provided empirical evidence for the existence of atoms. Before this paper, atoms were recognized as a useful concept, but physicists and chemists hotly debated whether atoms were real entities. Einstein's statistical discussion of atomic behavior gave experimentalists a way to count atoms by looking through an ordinary microscope. Wilhelm Ostwald, one of the leaders of the anti-atom school, later told Arnold Sommerfeld that he had been converted to a belief in atoms by Einstein's complete explanation of Brownian motion.[15] Brownian motion was also explained by Louis Bachelier in 1900.

Einstein's third paper that year, "On the Electrodynamics of Moving Bodies" ("Zur Elektrodynamik bewegter Körper"), was published in June 1905. This paper introduced the special theory of relativity, a theory of time, distance, mass and energy which was consistent with electromagnetism, but omitted the force of gravity. While developing this paper, Einstein wrote to Mileva about "our work on relative motion", and this has led some to ask whether Mileva played a part in its development.

A few historians of physics believe that Einstein was aware that the famous French mathematical physicist Henri Poincaré had already published the equations of relativity, a few weeks before Einstein submitted his paper. Most believe their work was independent and varied in many crucial ways. Similarly, it is debatable if he knew the 1904 paper of Hendrik Antoon Lorentz which contained most of the theory and to which Poincaré referred. Most historians, however, believe that Einsteinian relativity varied in many key ways from other theories of relativity which were circulating at the time, and that much of the questions about priority stem from the misleading trope of portraying Einstein as a genius working in total isolation.[16]

In a fourth paper, "Does the Inertia of a Body Depend Upon Its Energy Content?", ("Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?"), published late in 1905, he showed that from relativity's axioms, it is possible to deduce the famous equation which shows the equivalence between matter and energy. The energy equivalence (E) of some amount of mass (m) is that mass times the speed of light (c) squared: E = mc². However, it was Poincaré who in 1900 first published the "energy equation" in slightly different form, namely as: m = E / c² — see also relativity priority dispute.

### Middle years

In 1906, Einstein was promoted to technical examiner second class. In 1908, Einstein was licensed in Bern, Switzerland, as a Privatdozent (unsalaried teacher at a university). During this time, Einstein described why the sky is blue in his paper on the phenomenon of critical opalescence, which shows the cumulative effect of scattering of light by individual molecules in the atmosphere.[17] In 1911, Einstein became first associate professor at the University of Zurich, and shortly afterwards full professor at the German language-section of the Charles University of Prague. While at Prague, Einstein published a paper calling on astronomers to test two predictions of his developing theory of relativity: a bending of light in a gravitational field, measurable at a solar eclipse; and a redshift of solar spectral lines relative to spectral lines produced on Earth's surface. A young German astronomer, Erwin Freundlich, began collaborating with Einstein and alerted other astronomers around the world about Einstein's astronomical tests.[18] In 1912, Einstein returned to Zurich to become full professor at the ETH Zurich. At that time, he worked closely with the mathematician Marcel Grossmann, who introduced him to Riemannian geometry. In 1912, Einstein started to refer to time as the fourth dimension (although H.G. Wells had done this in 1895 in The Time Machine).

In 1914, just before the start of World War I, Einstein settled in Berlin as professor at the local university and became a member of the Prussian Academy of Sciences. He took Prussian citizenship. From 1914 to 1933, he served as director of the Kaiser Wilhelm Institute for Physics in Berlin. He also held the position of extraordinary professor at the University of Leiden from 1920 until 1946, where he regularly gave guest lectures.

In 1917, Einstein published "On the Quantum Mechanics of Radiation" ("Zur Quantentheorie der Strahlung," Physikalische Zeitschrift 18, 121–128). This article introduced the concept of stimulated emission, the physical principle that allows light amplification in the laser. He also published a paper that year that used the general theory of relativity to model the behavior of the entire universe, setting the stage for modern cosmology. In this work he created his self-described "worst blunder": the cosmological constant.

The Einsteins' second son, Eduard Einstein, was born on July 28, 1910. Their first son, Hans Albert Einstein, became a professor of hydraulic engineering at the University of California, Berkeley, having little interaction with his father, but sharing his love for sailing and music. Eduard, the younger brother, intended to practice as a Freudian analyst but was institutionalized for schizophrenia and died in an asylum. Einstein divorced Mileva on February 14, 1919, and married his cousin Elsa Löwenthal (born Einstein: Löwenthal was the surname of her first husband, Max) on June 2, 1919. Elsa was Albert's first cousin (maternally) and his second cousin (paternally). She was three years older than Albert, and had nursed him to health after he had suffered a partial nervous breakdown combined with a severe stomach ailment; there were no children from this marriage.

#### General relativity

In November 1915, Einstein presented a series of lectures before the Prussian Academy of Sciences in which he described a new theory of gravity, known as general relativity. The final lecture ended with his introduction of an equation that replaced Newton's law of gravity, the Einstein field equation.[19] This theory considered all observers to be equivalent, not only those moving at a uniform speed. In general relativity, gravity is no longer a force (as it is in Newton's law of gravity) but is a consequence of the curvature of space-time.

Einstein's published papers on general relativity were not available outside of Germany due to the war. News of Einstein's new theory reached English-speaking astronomers in England and America via Dutch physicists Hendrik Antoon Lorentz and Paul Ehrenfest and their colleague Willem de Sitter, Director of Leiden Observatory. Arthur Stanley Eddington in England, who was Secretary of the Royal Astronomical Society, asked de Sitter to write a series of articles in English for the benefit of astronomers. He was fascinated with the new theory and became a leading proponent and popularizer of relativity.[20] Most astronomers did not like Einstein's geometrization of gravity and believed that his light bending and gravitational redshift predictions would not be correct. In 1917, astronomers at Mt. Wilson Observatory in southern California published results of spectroscopic analysis of the solar spectrum that seemed to indicate that there was no gravitational redshift in the Sun.[21] In 1918, astronomers at Lick Observatory in northern California obtained photographs at a solar eclipse visible in the United States. After the war ended, they announced results claiming that Einstein's general relativity prediction of light bending was wrong; but they never published their results due to large probable errors.[22]

During a solar eclipse in 1919, Arthur Eddington supervised measurements of the bending of star light as it passed close to the Sun, resulting in star positions appearing further away from the Sun. This effect is called gravitational lensing and amounts to twice the Newtonian prediction. The observations were carried out in Sobral, Ceará, Brazil, as well as on the island of Principe, at the west coast of Africa. Eddington announced that the results confirmed Einstein's prediction and The Times reported that confirmation on November 7 of that year, thus cementing Einstein's fame.

Many scientists were still unconvinced for various reasons ranging from the scientific (disagreement with Einstein's interpretation of the experiments, belief in the ether or that an absolute frame of reference was necessary) to the psycho-social (conservatism, anti-Semitism). In Einstein's view, most of the objections were from experimentalists with very little understanding of the theory involved.[23] Einstein's public fame which followed the 1919 article created resentment among these scientists some of which lasted well into the 1930s.[24]

On March 30, 1921, Einstein went to New York to give a lecture on his new Theory of Relativity, the same year he was awarded the Nobel Prize. Though he is now most famous for his work on relativity, it was for his earlier work on the photoelectric effect that he was given the Prize, as his work on general relativity was still disputed. The Nobel committee decided that citing his less-contested theory in the Prize would gain more acceptance from the scientific community.

#### Copenhagen interpretation

In 1909 Einstein presented a paper [25] to a gathering of physicists on the history of aether theories and, more importantly, on the quantization of light. In this and an earlier 1909 paper, Einstein showed that the energy quanta introduced by Max Planck also carried a well-defined momentum and acted in many respects as if they were independent, point-like particles. This paper marks the introduction of the modern "photon" concept (although the term itself was introduced much later, in a 1926 paper by Gilbert N. Lewis). Even more importantly, Einstein showed that light must be simultaneously a wave and a particle, and foretold correctly that physics stood on the brink of a revolution that would require them to unite these dual natures of light. However, his own proposal for a solution — that Maxwell's equations for electromagnetic fields be modified to allow wave solutions that are bound to singularities of the field — was never developed, although it may have influenced Louis de Broglie's pilot wave hypothesis for quantum mechanics.

##### Determinism

Beginning in the mid-1920s, as the original quantum theory was replaced with a new theory of quantum mechanics, Einstein voiced his objections to the Copenhagen interpretation of the new equations. His opposition in this regard would continue all his life. The majority see the reason for his objection in terms of the view that he was a rigid determinist (see determinism). They would cite a 1926 letter to Max Born, where Einstein made the remark which history recalls the most:[26]

Quantum mechanics is certainly imposing. But an inner voice tells me it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the Old One. I, at any rate, am convinced that He does not throw dice.

To this, Bohr, who sparred with Einstein on quantum theory, retorted, "Stop telling God what He must do!" The Bohr-Einstein debates on foundational aspects of quantum mechanics happened during the Solvay Conferences. Another important part of Einstein's viewpoint is the famous 1935 paper[27] written by Einstein, Podolsky, and Rosen. Some physicists see this work as further supporting the notion that Einstein was a determinist.

There is a case to be made, however, for a quite different view of Einstein's objections to quantum orthodoxy. Einstein himself made further statements beyond that just given, and an emphatic comment on the matter was made by his contemporary Wolfgang Pauli. The above 'God does not play dice' quotation was something stated quite early, and Einstein's later statements were concerned with other issues. The Wolfgang Pauli quotation is as follows:[28]

…I was unable to recognize Einstein whenever you talked about him in either your letter or your manuscript. It seemed to me as if you had erected some dummy Einstein for yourself, which you then knocked down with great pomp. In particular Einstein does not consider the concept of `determinism' to be as fundamental as it is frequently held to be (as he told me emphatically many times) …he disputes that he uses as a criterion for the admissibility of a theory the question "Is it rigorously deterministic?"… he was not at all annoyed with you, but only said that you were a person who will not listen.
(emphasis due to Pauli)

##### Incompleteness and realism

Many of Einstein's comments indicate his belief that quantum mechanics is 'incomplete'. This was first asserted in the famous 1935 Einstein, Podolsky, Rosen (EPR paradox) paper,[29] and it appears again in the 1949 book Albert Einstein, Philosopher-Scientist.[30] The "EPR" paper — entitled "Can Quantum Mechanical Description of Physical Reality Be Considered Complete?" — has Einstein concluding: "While we have thus shown that the wave function does not provide a complete description of the physical reality, we left open the question of whether or not such a description exists. We believe, however, that such a theory is possible."

In the Schilpp book,[31] Einstein sets up a fascinating experimental proposal somewhat similar to Schroedinger's cat. He begins by addressing of the problem of the radioactive decay of an atom. If one begins with an undecayed atom and one waits a certain time interval, then quantum theory gives the probability that the atom has undergone the transformation of radioactive decay. Einstein then imagines the following system as a means to detect the decay:

Rather than considering a system which comprises only a radioactive atom (and its process of transformation), one considers a system which includes also the means for ascertaining the radioactive transformation — for example, a Geiger-counter with automatic registration mechanism. Let this include a registration-strip, moved by a clockwork, upon which a mark is made by tripping the counter. True, from the point of view of quantum mechanics this total system is very complex and its configuration space is of very high dimension. But there is in principle no objection to treating this entire system from the standpoint of quantum mechanics. Here too the theory determines the probability of each configuration of all coordinates for every time instant. If one considers all configurations of the coordinates, for a time large compared with the average decay time of the radioactive atom, there will be (at most) one such registration-mark on the paper strip. To each co-ordinate- configuration must correspond a definite position of the mark on the paper strip. But, inasmuch as the theory yields only the relative probability of the thinkable coordinate-configurations, it also offers only relative probabilities for the positions of the mark on the paperstrip, but no definite location for this mark.

Einstein continues:

…If we attempt [to work with] the interpretation that the quantum-theoretical description is to be understood as a complete description of the individual system, we are forced to the interpretation that the location of the mark on the strip is nothing which belongs to the system per se, but that the existence of that location is essentially dependent upon the carrying out of an observation made on the registration-strip. Such an interpretation is certainly by no means absurd from a purely logical point of standpoint; yet there is hardly anyone who would be inclined to consider it seriously. For, in the macroscopic sphere it simply is considered certain that one must adhere to the program of a realistic description in space and time; whereas in the sphere of microscopic situations, one is more readily inclined to give up, or at least to modify, this program."
(emphasis due to Einstein)

Einstein never rejected probabilistic techniques and thinking, in and of themselves. Einstein himself was a great statistician,[32] using statistical analysis in his works on Brownian motion and photoelectricity and in papers published before 1905; Einstein had even discovered Gibbs ensembles. According to the majority of physicists, however, he believed that indeterminism constituted a criterion for strong objection to a physical theory. Pauli's testimony contradicts this, and Einstein's own statements indicate a focus on incompleteness, as his major concern.

More recent times have given us another twist to this business. John Stewart Bell discovered further interesting results (Bell's Theorem and Bell's inequality) in his researches on the Einstein, Podolsky, and Rosen paper. There is a divergence in thinking as to the conclusions derivable from this, in conjunction with the EPR analysis. According to Bell, quantum nonlocality has been established, while others see the death of determinism.

##### Summary

Einstein agreed that the quantum theory was the best available, but he looked for a more "complete" explanation, i.e., either more deterministic or one that could more fundamentally explain the reason for probabilities in a logical way. He could not abandon the belief that physics described the laws that govern "real things", nor could he abandon the belief that there are no explanations that contain contradictions, which had driven him to his successes explaining photons, relativity, atoms, and gravity.

#### Bose-Einstein statistics

In 1924, Einstein received a short paper from a young Indian physicist named Satyendra Nath Bose describing light as a gas of photons and asking for Einstein's assistance in publication. Einstein realized that the same statistics could be applied to atoms, and published an article in German (then the lingua franca of physics) which described Bose's model and explained its implications. Bose-Einstein statistics now describe any assembly of these indistinguishable particles known as bosons. The Bose-Einstein condensate phenomenon was predicted in the 1920s by Bose and Einstein, based on Bose's work on the statistical mechanics of photons, which was then formalized and generalized by Einstein. The first such condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of Colorado at Boulder. Einstein's original sketches on this theory were recovered in August 2005 in the library of Leiden University.[33]

Einstein also assisted Erwin Schrödinger in the development of the quantum Boltzmann distribution, a mixed classical and quantum mechanical gas model although he realized that this was less significant than the Bose-Einstein model and declined to have his name included on the paper.

#### Einstein refrigerator

In 1926, Einstein and former student Leó Szilárd co-invented the Einstein refrigerator.[34] On November 11, 1930, US patent 1,781,541 was awarded to Albert Einstein and Leó Szilárd for the refrigerator. The patent covered a thermodynamic refrigeration cycle providing cooling with no moving parts, at a constant pressure, with only heat as an input. The refrigeration cycle used ammonia, butane, and water.

#### World War II

When Adolf Hitler came to power in January 1933, Einstein was a guest professor at Princeton University, a position which he took in December 1932, after an invitation from the American educator, Abraham Flexner. In 1933, the Nazis passed "The Law of the Restoration of the Civil Service" which forced all Jewish university professors out of their jobs, and throughout the 1930s a campaign to label Einstein's work as "Jewish physics"—in contrast with "German" or "Aryan physics"—was led by Nobel laureates Philipp Lenard and Johannes Stark. With the assistance of the SS, the Deutsche Physik supporters worked to publish pamphlets and textbooks denigrating Einstein's theories and attempted to politically blacklist German physicists who taught them, notably Werner Heisenberg. Einstein renounced his Prussian citizenship and stayed in the United States, where he was given permanent residency. He accepted a position at the newly founded Institute for Advanced Study in Princeton, NJ, where he concentrated on developing a unified field theory (see below). Einstein became an American citizen in 1940, though he still retained Swiss citizenship.

In 1939, under the encouragement of Szilárd, Einstein sent a letter to President Franklin Delano Roosevelt urging the study of nuclear fission for military purposes, under fears that the Nazi government would be first to develop nuclear weapons. Roosevelt started a small investigation into the matter which eventually became the massive Manhattan Project. Einstein himself did not work on the bomb project, however.

The International Rescue Committee was founded in 1933 at the request of Albert Einstein to assist opponents of Adolf Hitler.

#### Unified field theory

Einstein's research efforts after developing the theory of general relativity consisted primarily of a long series of attempts to generalize his theory of gravitation in order to unify and simplify the fundamental laws of physics, particularly gravitation and electromagnetism. In 1950 he described this work, which he referred to as the Unified Field Theory, in a Scientific American article. Einstein was guided by a belief in a single origin for the entire set of physical laws.

Einstein became increasingly isolated in his research on a generalized theory of gravitation and his attempts were ultimately unsuccessful. In particular, his pursuit of a unification of the fundamental forces ignored work in the physics community at large (and vice versa), most notably the discovery of the strong and weak nuclear forces, which were not understood independently until around 1970, fifteen years after Einstein's death. Einstein's goal of unifying the laws of physics under a single model survives in the current drive for unification of the forces.

### Final years

In 1948, Einstein served on the original committee which resulted in the founding of Brandeis University. A portrait of Einstein was taken by Yousuf Karsh on February 11 of that year. In 1952, the Israeli government proposed to Einstein that he take the post of second president. He declined the offer, and is believed to be the only United States citizen ever to have been offered a position as a foreign head of state. Einstein's refusal might have stemmed from his disapproval of some of the Israeli policies during the war of independence. In a letter he signed, along with other Jewish leaders in the U.S., he criticised the Freedom Party under the leadership of Menachem Begin for "Nazi and Fascist" methods and philosophy.[35]. On March 30, 1953, Einstein released a revised unified field theory.

He died at 1:15 AM[36] in Princeton hospital[37] in Princeton, New Jersey, on April 18, 1955 at the age of 76 from internal bleeding, which was caused by the rupture of an aortic aneurism, leaving the Generalized Theory of Gravitation unsolved. The only person present at his deathbed, a hospital nurse, said that just before his death he mumbled several words in German that she did not understand. He was cremated without ceremony on the same day he died at Trenton, New Jersey, in accordance with his wishes. His ashes were scattered at an undisclosed location.

An autopsy was performed on Einstein by Dr. Thomas Stoltz Harvey, who removed and preserved his brain. Harvey found nothing unusual with his brain, but in 1999 further analysis by a team at McMaster University revealed that his parietal operculum region was missing and, to compensate, his inferior parietal lobe was 15% wider than normal.[38] The inferior parietal region is responsible for mathematical thought, visuospatial cognition, and imagery of movement. Einstein's brain also contained 73% more glial cells than the average brain.

## Personality

### Religious views

Einstein was an Honorary Associate of the Rationalist Press Association beginning in 1934, and was an admirer of Ethical Culture.[39] He served on the advisory board of the First Humanist Society of New York.[40][41]

#### Quotations on religion

The religion of the future will be a cosmic religion. It should transcend personal God and avoid dogma and theology. Covering both the natural and the spiritual, it should be based on a religious sense arising from the experience of all things natural and spiritual as a meaningful unity. Buddhism answers this description. If there is any religion that could cope with modern scientific needs it would be Buddhism.[42]
I came — though the child of entirely irreligious (Jewish) parents — to a deep religiousness, which, however, reached an abrupt end at the age of twelve.[43]
I do not think that it is necessarily the case that science and religion are natural opposites. In fact, I think that there is a very close connection between the two. Further, I think that science without religion is lame and, conversely, that religion without science is blind. Both are important and should work hand-in-hand.[44]
A Jew who sheds his faith along the way, or who even picks up a different one, is still a Jew.[45]

As an adult, he called his religion a "cosmic religious sense".[46]

In The World As I See It he wrote:

You will hardly find one among the profounder sort of scientific minds without a peculiar religious feeling of his own. But it is different from the religion of the naive man.
For the latter God is a being from whose care one hopes to benefit and whose punishment one fears; a sublimation of a feeling similar to that of a child for its father, a being to whom one stands to some extent in a personal relation, however deeply it may be tinged with awe.
But the scientist is possessed by the sense of universal causation. The future, to him, is every whit as necessary and determined as the past. There is nothing divine about morality, it is a purely human affair. His religious feeling takes the form of a rapturous amazement at the harmony of natural law, which reveals an intelligence of such superiority that, compared with it, all the systematic thinking and acting of human beings is an utterly insignificant reflection.[47]

In response to the telegrammed question of New York's Rabbi Herbert S. Goldstein in 1929: "Do you believe in God? Stop. Answer paid 50 words." Einstein replied "I believe in Spinoza's God, Who reveals Himself in the lawful harmony of the world, not in a God Who concerns Himself with the fate and the doings of mankind." Note that Einstein replied in only 25 (German) words. Spinoza was a naturalistic pantheist.

### Scientific philosophy

In the "Copenhagen Interpretation" section (1.3.2) above, reference was made to the disagreement regarding Einstein's actual position regarding the quantum theory. The famous quotation "God does not play dice" is often used to support the majority view that he disliked the theory due to its indeterminism.

Others make the case for a different view. They note that the 1926 "Dice" quotation occurred when the quantum theory was just in its first year of discovery and in the subsequent 30 years of his life, one would be hard pressed to find a similar comment from the man. Instead Einstein focused on the conceptually independent subject of 'incompleteness'. This attention is shown both in his 1935 "EPR" paper, and in his 1949 Geiger counter registration strip thought-experiment (see section 1.3.2.2). Further evidence against the "Einstein-determinist" view is W. Pauli's quotation: "he (Einstein) disputes that he uses as a criterion for the admissibility of a theory the question 'Is it rigorously deterministic?'".

In favor of the deterministic view are the following statements of Einstein:

But the scientist is possessed by the sense of universal causation. The future, to him, is every whit as necessary and determined as the past.[48]

and:

People like us, who believe in physics, know that the distinction between past, present, and future is only a stubbornly persistent illusion.[49]

His devotion to Schopenhauer can be cited:

I do not believe in freedom of the will. Schopenhauer's words: “Man can do what he wants, but he cannot will what he wills ” accompany me in all situations throughout my life and reconcile me with the actions of others even if they are rather painful to me. This awareness of the lack of freedom of will preserves me from taking too seriously myself and my fellow men as acting and deciding individuals and from losing my temper.[50]

Einstein believed that true theorists always take some position on the metaphysics behind what they do:

I believe that every true theorist is a kind of tamed metaphysicist, no matter how pure a 'positivist' he may fancy himself. The metaphysicist believes that the logically simple is also the real. The tamed metaphysicist believes that not all that is logically simple is embodied in experienced reality, but that the totality of all sensory experience can be 'comprehended' on the basis of a conceptual system built on premises of great simplicity.[51]

The following general assessment was given by his colleague Nathan Rosen:

I think that the things which impressed me most were the simplicity of his thinking and his faith in the ability of the human mind to understand the workings of nature. Throughout his life, Einstein believed the human reason was capable of leading to theories that would provide correct descriptions of physical phenomena. In building a theory, his approach had something in common with that of an artist; he would aim for simplicity and beauty (and beauty for him was, after all, essentially simplicity). The crucial question that he would ask, when weighing an element of a theory was: "Is it reasonable?" No matter how successful a theory appeared to be, if it seemed to him not to be reasonable (the German word that he used was "vernunftig"), he was convinced that the theory could not provide a really fundamental understanding of nature.[52]

### Political views

Einstein considered himself a pacifist[53] and humanitarian,[54] and in later years, a committed democratic socialist. He once said, "I believe Gandhi's views were the most enlightened of all the political men of our time. We should strive to do things in his spirit: not to use violence for fighting for our cause, but by non-participation of anything you believe is evil." Deeply influenced by Gandhi, Einstein once said of Gandhi, "Generations to come will scarce believe that such a one as this ever in flesh and blood walked upon this earth." Einstein's views were sometimes controversial. In a 1949 article entitled "Why Socialism?",[55] Albert Einstein described the "predatory phase of human development", exemplified by a chaotic capitalist society, as a source of evil to be overcome. He disapproved of the totalitarian regimes in the Soviet Union and elsewhere, and argued in favor of a democratic socialist system which would combine a planned economy with a deep respect for human rights. Einstein was a co-founder of the liberal German Democratic Party and a member of the AFL-CIO-affiliated union the American Federation of Teachers.

Einstein was very much involved in the Civil Rights movement. He was a close friend of Paul Robeson for over 20 years. Einstein was a member of several civil rights groups (including the Princeton chapter of the NAACP) many of which were headed by Paul Robeson. He served as co-chair with Paul Robeson of the American Crusade to End Lynching. When W.E.B. DuBois was frivolously charged with being a communist spy during the McCarthy era while he was in his 80s, Einstein volunteered as a character witness in the case. The case was dismissed shortly after it was announced that he was to appear in that capacity. Einstein was quoted as saying that "racism is America's greatest disease".

The U.S. FBI kept a 1,427 page file on his activities and recommended that he be barred from immigrating to the United States under the Alien Exclusion Act, alleging that Einstein "believes in, advises, advocates, or teaches a doctrine which, in a legal sense, as held by the courts in other cases, 'would allow anarchy to stalk in unmolested' and result in 'government in name only'", among other charges. They also alleged that Einstein "was a member, sponsor, or affiliated with thirty-four communist fronts between 1937 and 1954" and "also served as honorary chairman for three communist organizations".[56] It should be noted that many of the documents in the file were submitted to the FBI, mainly by civilian political groups, and not actually written by FBI officials.

Einstein opposed tyrannical forms of government, and for this reason (and his Jewish background), opposed the Nazi regime and fled Germany shortly after it came to power. At the same time, Einstein's anarchist nephew Carl Einstein, who shared many of his views, was fighting the fascists in the Spanish Civil War. Einstein initially favored construction of the atomic bomb, in order to ensure that Hitler did not do so first, and even sent a letter to President Roosevelt (dated August 2, 1939, before World War II broke out, and probably written by Leó Szilárd) encouraging him to initiate a program to create a nuclear weapon. Roosevelt responded to this by setting up a committee for the investigation of using uranium as a weapon, which in a few years was superseded by the Manhattan Project.

After the war, though, Einstein lobbied for nuclear disarmament and a world government: "I do not know how the Third World War will be fought, but World War IV will be fought with sticks and stones."[57]

While Einstein was a supporter of Zionism in the cultural sense, he often expressed reservations regarding its application in terms of nationalism. During a speech at the Commodore Hotel in New York, he told the crowd "My awareness of the essential nature of Judaism resists the idea of a Jewish state with borders, an army, and a measure of temporal power, no matter how modest. I am afraid of the inner damage Judaism will sustain."[58] He also signed an open letter published in the New York Times condemning Menachem Begin and his nationalistic Herut party, especially for the treatment of the indigenous Arabs at Deir Yassin by Herut’s predecessor Irgun.

Despite these reservations, he was active in the establishment of the Hebrew University in Jerusalem, which published (1930) a volume titled About Zionism: Speeches and Lectures by Professor Albert Einstein, and to which Einstein bequeathed his papers. In later life, in 1952, he was offered the post of second president of the newly created state of Israel, but declined the offer, saying that he lacked the necessary people skills. However, Einstein was deeply committed to the welfare of Israel and the Jewish people for the rest of his life.

Albert Einstein was closely associated with plans for what the press called "a Jewish-sponsored non-quota university," from August 19, 1946, with the announcement of the formation of the Albert Einstein Foundation for Higher Learning, Inc. until June 22, 1947, when he withdrew support and barred the use of his name by the foundation. The university opened in 1948 as Brandeis University.

Einstein, along with Albert Schweitzer and Bertrand Russell, fought against nuclear tests and bombs. As his last public act, and just days before his death, he signed the Russell-Einstein Manifesto, which led to the Pugwash Conferences on Science and World Affairs. His letter to Russell read:

Dear Bertrand Russell,
Thank you for your letter of April 5. I am gladly willing to sign your excellent statement. I also agree with your choice of the prospective signers.
With kind regards, A. Einstein

## Citizenship

Einstein was born a German citizen. At the age of 17, on January 28, 1896, he was released from his German citizenship by his own request and with the approval of his father. He remained stateless for five years. On February 21, 1901 he gained Swiss citizenship, which he never revoked. Einstein obtained Prussian citizenship in April 1914 when he entered the Prussian civil service, but due to the political situation and the persecution of Jewish people in Nazi Germany, he left civil service in March 1933 and thus also lost the Prussian citizenship. On October 1, 1940, Einstein became an American citizen. He remained both an American and a Swiss citizen until his death on April 18, 1955.

## Popularity and cultural impact

According to "A Ranking of the Most Influential Persons in History", he is "the greatest scientist of the twentieth century and one of the supreme intellects of all time".[59] Einstein's popularity has also led to widespread use of Einstein's image in advertising and merchandising, including the registration of "Albert Einstein" as a trademark.

### Entertainment

Albert Einstein has become the subject of a number of novels, films and plays, including Jean-Claude Carrier's 2005 French novel, Einstein S'il Vous Plait (Please Mr Einstein), Nicolas Roeg's film Insignificance, Fred Schepisi's film I.Q. (where he was portrayed by Walter Matthau), Alan Lightman's novel Einstein's Dreams, and Steve Martin's comedic play Picasso at the Lapin Agile. He was the subject of Philip Glass's groundbreaking 1976 opera Einstein on the Beach. His humorous side is also the subject of Ed Metzger's one-man play Albert Einstein: The Practical Bohemian.

He is often used as a model for depictions of mad scientists and absent-minded professors in works of fiction; his own character and distinctive hairstyle suggest eccentricity, or even lunacy, and are widely copied or exaggerated. TIME magazine writer Frederic Golden referred to Einstein as "a cartoonist's dream come true."[60]

On Einstein's 72nd birthday in 1951, the UPI photographer Arthur Sasse was trying to coax him into smiling for the camera. Having done this for the photographer many times that day, Einstein stuck out his tongue instead.[61] The image has become an icon in pop culture for its contrast of the genius scientist displaying a moment of levity. Yahoo Serious, an Australian film maker, used the photo as an inspiration for the intentionally anachronistic movie Young Einstein. The image is also used in a poster used in the UK as part of dyslexia education, which has a string of posters showing great scientists, thinkers and artists and talks about the unfounded (not specified within the posters) claims that they had/have dyslexia.

### Speculation and controversy

There are innumerable speculations which suggest that Einstein was a poor student, a slow learner, or had a form of autism (such as High-functioning autism, or Asperger syndrome), dyslexia, and/or attention-deficit hyperactivity disorder. According to the authoritative biography by Pais (page 36, among others), such speculations are unfounded. Some researchers have periodically claimed otherwise,[62] but most historians and doctors are skeptical of retrospective medical diagnoses, especially for complex and, in the case of ADHD, diagnostically-controversial conditions. Examinations of Albert Einstein's brain after his death have not produced any conclusive evidence of any particular condition.

The recurring rumor that Einstein failed in mathematics during his education is untrue. On the contrary, Einstein has always shown great talent at mathematics. The grades system of Switzerland where 6 is the best achievable mark may have stirred confusion amongst those with the German grades system in mind, 1 being the best achievable mark there. By age 15 however, Albert Einstein received poor grades in history, languages and geography[63].

### Personal relations

Letters written by Einstein to his relatives and kept at the Hebrew University of Jerusalem, have revealed that during the course of his life, he had a dozen lovers, two of whom he married.[64] Barbara Wolff of the Hebrew University's Albert Einstein Archives has made public about 3,500 pages of correspondence including letters to his first and second wives and children between the years 1912–1955. In letters to his second wife Elsa and her daughter Margot he claimed that he had been showered with unwanted attention from women. One of his lovers, a Berlin socialite Ethel Michanowski, "followed me [to England], and her chasing me is getting out of control." His son Eduard's schizophrenia troubled Einstein greatly, and he often expressed the idea that it would have been better if Eduard had not been born. He adored his stepdaughter and in a letter to Elsa in 1924, he writes: "I love her [Margot] as much as if she were my own daughter, perhaps even more so, since who knows what kind of brat she would have become [had I fathered her]." The letters have been claimed as evidence to dispel myths that Einstein was cold towards his family.

### Licensing

Einstein bequeathed his estate, as well as the use of his image (see personality rights), to the Hebrew University of Jerusalem.[65] Einstein actively supported the university during his life and this support continues with the royalties received from licensing activities. The Roger Richman Agency licences the commercial use of the name "Albert Einstein" and associated imagery and likenesses of Einstein, as agent for the Hebrew University of Jerusalem. As head licensee the agency can control commercial usage of Einstein's name which does not comply with certain standards (e.g., when Einstein's name is used as a trademark, the ™ symbol must be used).[66] As of May, 2005, the Roger Richman Agency was acquired by Corbis.

### Honors

Einstein received a number of posthumous honors. For example:

Among Einstein's many namesakes are:

## Works by Einstein

Einstein published over fifty scientific papers during his lifetime. He also published several non-scientific works, including About Zionism (1930), Why War? (1933), The World As I See It (1934), and Out of My Later Years (1950).

## Notes

1. Dudley Herschbach, "Einstein as a Student," Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA, page 3, web: HarvardChem-Einstein-PDF: about Max Talmud visited on Thursdays for 6 years.
2. Talmey, M., The Relativity Theory Simplified and the Formative Years of its Inventor, Falcon Press, 1932.
3. Highfield.
4. Fölsing, A., Albert Einstein, Penguin Books, 1997, p. 37.
5. Ibid.
6. Albert Einstein Collected Papers, vol. 1, doc. 67
7. Stachel, J. Einstein from B to Z, Birkhäuser, 2002, p. 41
8. The institute / IPI / Federal Institute of Intellectual Property. Retrieved on November 21, 2005.
9. Peter Galison, "Einstein's Clocks: The Question of Time" Critical Inquiry 26, no. 2 (Winter 2000): 355–389, on 368.
10. Pais, A., Einstein Was Here, Oxford University Press, 1994, pp. 1-29; Holton, G., Einstein, History, and Other Passions, 1996, Harvard University Press, pp. 177-193; Stachel, J., Einstein from B to Z, Birkhäuser, 2002, pp. 26-38; 39-55; Martinez, A. A., "Handling Evidence in History", 2005: https://webspace.utexas.edu/aam829/1/m/Maric_files/EvidenceMaric.pdf
11. Stachel, J. (ed) Einstein's Miraculous Year: Five Papers that Changed the Face of Physics , 1905 edition, Princeton University Press, [pp. liv-lxiii http://www.esterson.org/Stachel_Joffe.htm]
12. https://webspace.utexas.edu/aam829/1/m/Maric_files/EvidenceMaric.pdf
13. Arguing about Einstein's wife (April 2004) - Physics World - PhysicsWeb (See above). Retrieved on November 21, 2005.
14. Peter Galison, "Einstein's Clocks: The Question of Time" Critical Inquiry 26, no. 2 (Winter 2000): 355–389, on 370.
15. Smoluchowski worked on Brownian motion at the same time as Einstein. He published in 1906 the same formula as Einstein (arrived at by a different method), except for a mistaken factor. See Paul Langevin’s 1908 paper ‘‘On the Theory of Brownian Motion’’. Retrieved on March 17, 2006. for details.
16. See, for example, Helge Kragh, "Einstein's Relativity, and Others'" in Quantum Generations: A History of Physics in the Twentieth Century (Princeton, NJ: Princeton University Press, 1999): 87-104. On Einstein's lack of total isolation, and differences between his an Poincaré's relativity theories, see Peter Galison, Einstein's clocks, Poincarés maps: empires of time (New York: W.W. Norton, 2003).
17. PBS - NOVA - Einstein's Big Idea - "Genius Among Geniuses", by Thomas Levenson
18. [Crelinsten, Jeffrey, "Einstein's Jury: The Race to Test Relativity," Princeton University Press, 2006]
19. David Hilbert actually published the field equation in an article that was dated five days before Einstein's lecture. But according to Thorne (pp. 117–118), Hilbert had discovered the correct derivation after "mulling over things he had learned" on a recent visit by Einstein to Gottingen. Thorne goes on to say "Quite naturally, and in accord with Hilbert's view of things, the resulting law of warpage was quickly given the name the Einstein field equation rather than being named after Hilbert. In fact without Einstein, the general relativistic laws of gravity might not have been discovered until several decades later." See Relativity priority disputes for more details.
20. Crelinsten, Einstein's Jury, pp. 94–98.
21. Crelinsten, pp. 103–108.
22. Crelinsten, pp. 114–119, 126–140.
23. See esp. Albert Einstein, "My Reply. On the Anti-Relativity Theoretical Co., Ltd. [August 27, 1920," in Klaus Hentschel, ed. Physics and National Socialism: An anthology of primary sources (Basel: Birkhaeuser, 1996), pp.1-5.
24. There is a good discussion of resentment towards Einstein's fame, especially among those German physicists who would later start the Deutsche Physik anti-Einsteinian movement, in the Introduction to Klaus Hentschel, ed. Physics and National Socialism: An anthology of primary sources (Basel: Birkhaeuser, 1996), on p.lxxi. For a discussion of astronomers' attitudes and debates about relativity, see Jeffrey Crelinsten, Einstein's Jury: The Race to Test Relativity (Princeton University Press, 2006), esp. chpts. 6, 9, 10 and 11.
25. Über die Entwicklung unserer Anschauungen über das Wesen und die Konstitution der Strahlung, available in its English translation The Development of Our Views on the Composition and Essence of Radiation
26. Letter from A. Einstein to M. Born dated December 12, 1926, as reproduced in Born, M., 1969. Physics in my generation. Springer-Verlag: p. 113. Because Einstein has been often misquoted, we give the two last original German sentences: "Die Theorie liefert viel, aber dem Geheimnis des Alten bringt sie uns kaum näher. Jedenfalls bin ich überzeugt, daß der nicht würfelt." Born's own translation: "The theory yields much, but it hardly brings us nearer to the secret of the Old One. In any case, I am convinced that he does not throw dice."
27. A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777 (1935)
28. M. Born (editor), The Born-Einstein-Letters, p. 221 (Macmillan, London (1971)).
29. A. Einstein, B. Podolsky, N. Rosen, Phys. Rev. 47:777 (1935)
30. P.A. Schilpp, Ed. Albert Einstein, Philosopher-Scientist, Tudor, N.Y. (1949).
31. p. 671
32. The Economist - Miraculous visions - 100 years of Einstein
33. Einstein archive at the Instituut-Lorentz. Retrieved on November 21, 2005.
34. Einstein's Refrigerator. Retrieved on November 21, 2005.
35. [1]
36. Neuroscience for Kids - "What Became of Albert Einstein's Brain?"
37. Historical Society of Princeton - "Einstein in Princeton"
38. BBC News : Sci/Tech : Why size mattered for Einstein. Retrieved on November 21, 2005.
39. The Humanist Way: An Introduction to Ethical Humanist Religion. Retrieved on February 25, 2006.
40. Charles Francis Potter. Retrieved on May 14, 2006.
41. Genesis of a Humanist Manifesto. Retrieved on May 14, 2006.
42. Error on call to Template:cite web: Parameters url and title must be specified.
43. Peter A. Bucky, et. al., The Private Albert Einstein (Kansas City, 1992), p. 85.
44. Peter A. Bucky, et. al., The Private Albert Einstein (Kansas City, 1992), p. 87.
45. Nathan Rosen p. 649 in Einstein: The Life and Times Avon Books, New York 1971.
46. Einstein : American Museum of Natural History. Retrieved on November 21, 2005.
47. Ibid.
48. Einstein, Albert. Why Socialism?, Monthly Review, May 1949. Retrieved on 2006-01-16.
49. Federal Bureau of Investigation - Freedom of Information Privacy Act. Retrieved on November 21, 2005.
50. Calaprice p. 173. Other versions of the quote exist.
51. Algemeiner.com - "The Death of Modern Zionism?", by Simon Jacobson
52. e.g. Hart, Michael H. [1978] (1992). The 100: A Ranking of the Most Influential Persons in History. Citadel Press. ISBN 0-8065-1350-0.  p. 52, "Albert Einstein, the greatest scientist of the twentieth century and one of the supreme intellects of all time..."
53. TIME 100: Person of the Century - Albert Einstein
54. mental_floss library. Retrieved on November 21, 2005.
55. See, i.e., Einstein and Newton 'had autism' Page accessed 16 September 2006. See also: People speculated to have been autistic
56. Encyclopaedia Britannica. 15th edition. Volume 18. "Albert Einstein". Page 155
57. Letters reveal Einstein love life, BBC News (11 July 2006).
58. http://aip.org/history/esva/einuse.htm. Retrieved on November 21, 2005.
59. ALBRT EINSTEIN BRAND LOGO. Retrieved on November 21, 2005.
60. the Albert Einstein College of Medicine of Yeshiva University. Retrieved on November 21, 2005.
61. Albert Einstein Medical Center. Retrieved on November 21, 2005.