Appendix C. Select Annotated Bibliography
This chronological list of papers provides brief descriptions of the majority of Einstein’s publications throughout his life. We did not include items we thought added little to our discussions of their themes in the relevant sections of the volume. In addition, we omitted Einstein’s reviews of books and articles written by others—Einstein wrote many of these between 1902 and 1905 especially—as well as his brief comments on other scientists’ articles and replies to comments about his own articles. The two best known of these are undoubtedly Einstein’s objections, later withdrawn, to the two seminal papers on expanding-universe cosmologies by Willem de Sitter (1918) and Alexander Friedmann (1922). We also omit the various remembrances about fellow scientists and other intellectuals, unless they are particularly memorable. Only a few of his published letters to journals are listed.
Einstein wrote many papers on unified field theories (UFTs) from the mid-1920s on, but only a representative sample of these are included. The inclusion of all of his UFT papers would weight this bibliography too heavily toward this one aspect of his career that was relatively unsuccessful. His UFT program is summarized in Part II, and some of his lesser-known papers on other topics are mentioned in the section on Scientific Sidelights, also in Part II.
During his early career, Einstein wrote carefully crafted papers that were the last word on the topics they addressed. Later in life, he was more likely to publish updates of work in progress.
1901
1. “Conclusions Drawn from the Phenomena of Capillarity” (Folgerungen aus den Capillaritätserscheinungen). Annalen der Physik 4 (1901): 513–523. Einstein’s first publication, dated December 13, 1900, but not published until the following March, discusses the phenomenon of capillarity in neutral liquids in studying the nature of intermolecular forces. The paper combines the use of both thermodynamic and molecular-theoretical methods.
1902
2. “On the Thermodynamic Theory of the Difference in Potentials between Metals and Fully Dissociated Solutions of Their Salts and on an Electrical Method for Investigating Molecular Forces” (Ueber die thermodynamische Theorie der Potentialdifferenz zwischen Metallen und vollständig dissociirten Lösungen ihrer Salze und über eine elektrische Methode zur Erforschung der Molekularkräfte). Annalen der Physik 8 (1902): 798–814. In this paper, Einstein discusses the conditions for the validity of the second law of thermodynamics, which became significant for his later work.
3. “Kinetic Theory of Thermal Equilibrium and of the Second Law of Thermodynamics” (Kinetische Theorie des Wärmegleichgewichtes und des zweiten Hauptsatzes der Thermodynamik). Annalen der Physik 9 (1902): 417–433. Einstein fills the gap in the mechanical foundations of the “general theory of heat,” demonstrating the validity of the equipartition theorem for any mechanical system. His mastery of this theorem would be a hallmark of his later approach to the quantum problem.
1903
4. “A Theory of the Foundations of Thermodynamics” (Eine Theorie der Grundlagen der Thermodynamik). Annalen der Physik 11 (1903): 170–187. Einstein shows that the concepts of temperature and entropy follow from the assumption of the energy principle and atomistic theory, assuming only the foundations of atomic physics and no other physical hypotheses. Among other results, he shows that the second law of thermodynamics is valid for systems that are not in equilibrium, thus addressing many real-world systems that are not well described by conventional kinetic theory.
1904
5. “On the General Molecular Theory of Heat” (Zur allgemeinen molekularen Theorie der Wärme). Annalen der Physik 14 (1904): 354–362. This paper is the culmination of Einstein’s efforts to generalize and extend the foundations of statistical physics and is his last paper devoted exclusively to the subject. Unknown to him, many of the ideas in these early papers had been anticipated by the reclusive American theorist Josiah Willard Gibbs. Einstein later remarked, “Had I been familiar with Gibbs’s book at that time, I would not have published those papers at all, but would have limited myself to the discussion of just a few points” (CPAE, Vol. 3, Doc. 10).
1905
6. “On a Heuristic Point of View concerning the Production and Transformation of Light” (Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt). Annalen der Physik 17 (1905): 132–148. Here Einstein expounds on the peculiar discrepancy existing between material bodies and radiation. He introduces the concept of light quanta and provides the basis for much further work in quantum theory, especially Bohr’s theory of the atom. He challenges the wave theory of light and shows that electromagnetic radiation interacts with matter as if the radiation has a granular structure, in describing the photoelectric effect. Einstein determined that a massless quantum of light, now called the photon, would have to impart the required energy according to Planck’s radiation law, in order to break the attractive forces holding the electrons in the metal. This theory was one of the milestones in the development of quantum mechanics, making Einstein the foremost pioneer in the field and opening the world of quantum physics. The first of the five great papers he published in 1905, it was largely responsible for earning him the Nobel Prize in physics sixteen years later.
7. A New Determination of Molecular Dimensions (Eine neue Bestimmung der Moleküldimensionen). Bern: Buchdruckerei Wyss, 1906. Also slightly revised in Annalen der Physik 19 (1906): 289–305, which has an appended supplement on pp. 305–306, and an erratum in 34 (1911): 591–592. Here we have Einstein’s doctoral dissertation, which he submitted to the University of Zurich in the spring of 1905 after withdrawing his first submission on a different topic in 1902. He combines the techniques of classical thermodynamics with those of the theory of diffusion to create a new method for determining molecular sizes. In proposing this work, he wanted to discover facts that would finally establish the existence of atoms of a precise finite size, since at the turn of the century the atom’s existence was still in contention. The approval of this thesis earned Einstein his doctorate. Although overshadowed in fame by his other papers of 1905, this important work is still one of his more frequently cited papers.
8. “On the Movement of Small Particles Suspended in Stationary Liquids Required by the Molecular-Kinetic Theory of Heat” (Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen). Annalen der Physik 17 (1905): 549–560. Einstein discusses Brownian motion, the irregular movement of microscopic particles suspended in a liquid, named after the eighteenth-century Scottish botanist who first observed it. As Einstein explained in a letter to his friend Conrad Habicht, in this paper he proved that microscopic particles carry out an observable random movement, when suspended in a liquid, that is generated by the thermal motion of atoms in the fluid. By inverting Boltzmann’s formula, Einstein describes its mathematics, deriving the probability of a macroscopic state for the distribution of gas molecules. This paper led to experiments validating the kinetic-molecular theory of heat. This is still one of Einstein’s most-cited papers and is often considered to be the most convincing demonstration of the reality of atoms.
9. “On the Electrodynamics of Moving Bodies” (Zur Elektrodynamik bewegter Körper). Annalen der Physik 17 (1905): 901–921. This important landmark in the development of physics is the first of Einstein’s two papers that founded the theory of special relativity (the second is no. 10). Here he employs a modification of the theory of space and time. By assuming that the speed of light is the same to every observer who moves at a constant velocity, he showed that space and time are not independent, and spacetime was born. According to Hermann Weyl in 1918, this theory “led to the discovery that time is associated as a fourth coordinate on an equal footing with the other three coordinates of space, and that the scene of material events, the world, is therefore a four-dimensional, metrical continuum.” It is arguably the most influential paper in all of twentieth-century physics, as its reformulation of kinematics has implications for essentially all fields of physics. Although the ideas developed in the paper were slowly emerging from the body of work on electromagnetic field theory, other theorists, even Henri Poincaré, failed to achieve Einstein’s insight: that the results of the theory were not mere effects of the electromagnetic field, but rather limitations imposed on our ability to measure space and time because there was a finite speed by which information about distant events could reach us.
10. “Does the Inertia of a Body Depend upon Its Energy Content?” (Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?). Annalen der Physik 18 (1905): 639–641. Einstein uses the postulates of the special theory of relativity to show that energy radiated is equivalent to mass lost, which is expressed in the famous equation E = mc2. He considers the conservation of energy of a radiating body in a system at rest and in a system in uniform motion relative to it. He concludes, for the first time, that “the mass of a body is a measure of its energy content.” This work ultimately helped solve the vexing question of the source of the Sun’s enormous energy output. The special theory of relativity paved the way for a deeper appreciation of symmetry criteria in physics and introduced new perceptions of space and time. Yet twenty-five years passed before experimental evidence in its favor emerged. Einstein credited Galileo, Newton, Maxwell, and Lorentz for laying the foundation for the theory.
1906
11. “On the Theory of Brownian Motion” (Zur Theorie der Brownschen Bewegung). Annalen der Physik 19 (1906): 371–381. Here Einstein presents his earlier ideas on Brownian motion in more elegant form, adding two new applications: the vertical distribution of a suspension under the influence of gravitation, and a calculation for a Brownian rotational movement for a rotating solid sphere.
12. “On the Theory of Light Production and Light Absorption” (Zur Theorie der Lichterzeugung und Lichtabsorption). Annalen der Physik 20 (1906): 199–206. Einstein argues that the fundamental concepts of mechanics and electrodynamics require drastic modification by quantum considerations, though in 1909 he reiterates that they should not be completely abandoned.
13. “The Principle of Conservation of Motion of the Center of Gravity and the Inertia of Energy” (Das Prinzip von der Erhaltung der Schwerpunktsbewegung und die Trägheit der Energie). Annalen der Physik 20 (1906): 627–633. In an ingenious thought experiment involving energy transport in a hollow cylinder, Einstein returns to the relationship between inertial mass and energy, giving general arguments for their complete equivalence. He shows that if light is transmitted from one end of the cylinder to the other, it could move the cylinder from the inside (in violation of our intuition based on Newton’s third law) unless the light carries mass with it, and thus its change of position affects the location of the cylinder’s center of mass.
14. “On the Method for the Determination of the Ratio of the Transverse and Longitudinal Mass of the Electron” (Über eine Methode zur Bestimmung des Verhältnisses der transversalen und longitudinalen Masse des Elektrons). Annalen der Physik 21 (1906): 583–586. Einstein suggests an experimental test of the equations of motion of the electron using cathode rays.
15. “Planck’s Theory of Radiation and the Theory of Specific Heat” (Die Plancksche Theorie der Strahlung und die Theorie der spezifischen Wärme). Annalen der Physik 22 (1907): 180–190. He published a short erratum on p. 800 of the same journal. This is Einstein’s first paper on the quantum theory of solids. In it, he makes a deduction of Planck’s radiation formula, and it is the first systematic introduction of probability factors in the mathematics of quantum theory. A classic paper, it offered a complete explanation for the specific heat of solids from absolute zero to above room temperature. According to this theory, solids lose the ability to absorb heat altogether as their temperature approaches absolute zero. This influential paper would encourage the development of the third law of thermodynamics.
16. “On the Limit of Validity of the Law of Thermodynamic Equilibrium and on the Possibility of a New Determination of the Elementary Quanta” (Über die Gültigkeitsgrenze des Satzes vom thermodynamischen Gleichgewicht und über die Möglichkeit einer neuen Bestimming der Elementarquanta). Annalen der Physik 22 (1907): 569–572. Einstein uses the thermodynamic approach to fluctuations in Brownian motion to predict voltage fluctuations in condensers. To test his theory, he needed a new, highly sensitive instrument—more sensitive than the available electrometers, which could measure only to a few thousandths of a volt. Einstein designed it, had it built, and famously called it his Maschinchen (little machine). He toyed with the idea of patenting it, but then dismissed the notion when manufacturers showed little interest. Instead, he decided to publish a paper on the basic features of the machine the following year.
17. “Theoretical Remarks on Brownian Motion” (Theoretische Bemerkungen über die Brownsche Bewegung). Zeitschrift für Elektrochemie und angewandte physikalische Chemie 13 (1907): 41–42. Einstein attempts to make the fundamental features of his theory accessible to readers with a moderate background in mathematics. He discusses some peculiarities of the statistical motion of suspended particles in a fluid that can hamper experimental verification.
18. “On the Possibility of a New Test of the Relativity Principle” (Über die Möglichkeit einer neuen Prüfung des Relativitätsprinzips). Annalen der Physik 23 (1907): 197–198. Einstein proposes a test of what has become known as the transverse Doppler effect, which is a direct measure of special relativistic time dilation. He shows that a particle moving transverse to the line of sight will still appear redshifted, but in an amount proportional to the square of its velocity, as opposed to the linear effect in the conventional Doppler shift observed when a body is moving along the line of sight.
19. “On the Inertia of Energy Required by the Relativity Principle” (Über die vom Relativitätsprinzip geforderte Trägheit der Energie). Annalen der Physik 23 (1907): 371–384. As in no. 13, Einstein discusses the relationship between inertial mass and energy, arguing for their complete equivalence, namely, every mass has an equivalent energy just as every form of energy has an equivalent mass. This relation maintains that a photon can convert into matter with the appropriate mass, and vice versa. He deduces the exact expression for the equivalence of mass and energy, that is, his celebrated equation E = mc2. He also returns to the question of the impossibility of superluminal velocities.
20. “On the Relativity Principle and the Conclusions Drawn from It” (Über das Relativitätsprinzip und die aus demselben gezogenen Folgerungen). Jahrbuch der Radioaktivität und Elektronik 4 (1907): 411–462. Einstein published some corrections to the paper the following year in vol. 5 (1908): 98–99. In this review article on relativity, Einstein summarizes the results of some of his earlier papers on the theory of relativity, sometimes simplifying his earlier proofs. It covers relativistic kinematics, optics, electromagnetic theory, and the relativistic dynamics of a particle and of an extended system. He proves that a body’s inertial and gravitational masses are equal to the same quantity E/c2 and therefore should be considered precisely equal to each other, the basis of the equivalence principle. This result would be the chief steppingstone to the 1915 theory on general relativity.
1908
21. “A New Electrostatic Method for the Measurement of Small Quantities of Electricity” (Eine neue elektrostatische Methode zur Messung kleiner Elektrizitätsmengen). Physikalische Zeitschrift 9 (1908): 216–217. Einstein published the basic features of his method for constructing the Maschinchen that he used in his work on no. 16.
22. “Elementary Theory of Brownian Motion” (Elementare Theorie der Brownschen Bewegung). Zeitschrift für Elektrochemie und angewandte physikalische Chemie 14 (1908): 235–239. An elementary account of Einstein’s theory of Brownian motion was needed, particularly by chemists who were trying to provide experimental support for it and often misunderstood it. Einstein elaborates especially on the relation between diffusion and osmotic pressure, and calculates the diffusion coefficient from the frictional resistance of the solvent fluid to the dissolved molecules.
23. “On the Fundamental Electromagnetic Equations for Moving Bodies” (Über die elektromagnetischen Grundgleichungen für bewegte Körper) (with Jakob Laub). Annalen der Physik 26 (1908): 532–540. A correction to this paper was published later in the year in vol. 27 (1908): 232, and a supplement the following year in vol. 28 (1909): 445–447. Elaborating on the relativistic transformation of Maxwell’s vacuum equations discussed in no. 8, Einstein and Laub also consider the displacement vector D and the magnetic induction B. See also no. 24.
24. “On the Ponderomotive Forces Exerted on Bodies at Rest in the Electromagnetic Field” (Über die im elektromagnetischen Felde auf ruhende Körper ausgeübten ponderomotorischen Kräfte) (with Jakob Laub). Annalen der Physik 26 (1908): 541–550. Einstein wrote nos. 23 and 24 in a three-week period with Jakob Laub, his first scientific collaborator, to address the problems of formulating relativistically invari ant equations for electromagnetic fields in moving media, first raised by Hermann Minkowski the year before.
1909
25. “On the Present Status of the Radiation Problem” (Zum gegenwärtigen Stand des Strahlungsproblems). Physikalische Zeitschrift 10 (1909): 185–193. In another article of the same title, written with Walter Ritz and published in the same volume, pp. 323–324, Einstein and Ritz summarize their differences on the radiation problem (Einstein advocates in that note the viewpoint that the preference for retarded electromagnetic potentials exhibited by physical systems is a consequence of the large number of charge particles in our universe. This viewpoint was later defined more concretely by the absorber theory of John Wheeler and Richard Feynman).
Responding to papers published by H. A. Lorentz, James Jeans, and Walter Ritz the preceding year in which they discussed their respective opinions on the radiation problem, Einstein elaborates the concept of the “statistical probability of a state” first introduced in no. 6. The new material includes the two arguments for the existence of light quanta based on the analysis of fluctuations in blackbody radiation. After making his first known attempt to find a field theory that would explain the structure of both matter and radiation, Einstein here admitted that he had not yet succeeded in finding a system of equations for both. This attempt was a forerunner of his later search for a unified field theory.
26. “On the Development of Our Views concerning the Nature and Constitution of Radiation” (Über die Entwickelung unserer Anschauungen über das Wesen und die Konstitution der Strahlung). Deutsche Physikalische Gesellschaft, Verhandlungen 7 (1909): 482–500. Also published the following month in Physikalische Zeitschrift 10 (1909): 817–825. Einstein had presented this lecture on September 21 at the 81st meeting of the Society of German Natural Scientists and Physicians held in Salzburg, Austria, the first such conference he attended. He summarized his views on radiation and for the first time publicly linked his work on relativity and the quantum hypothesis. This is the first synthesis showing the profound changes in the concept of light ushered in by the theory of relativity and of the important implications of this change on the development of physics. He reiterates that light, like matter, has an independent existence.
1910
27. “The Principle of Relativity and Its Consequences in Modern Physics” (Le principe de relativité et ses conséquences dans la physique moderne). Archives des sciences physiques et naturelles 29 (1910): 5–28, and 125–144. Published as two separate papers in the same journal and translated from German to French by Edouard Guillaume, this work is a general survey of the history and essence of the theory of relativity, along with its applications. In a letter to Jakob Laub dated August 27, Einstein stated that the paper did not contain any new insights, that it “merely comprises a rather general discussion of the epistemological foundations of the theory of relativity, no new views whatsoever, and almost nothing that is quantitative.”
28. “On the Theory of Light Quanta and the Question of the Localization of Electromagnetic Energy” (Sur la théorie des quantités lumineuses et la question de la localisation de l’énergie électromagnétique). Archives des sciences physiques et naturelles 29 (1910): 525–528. Einstein presented this paper in May at a meeting of the Swiss Physical Society in Neuchâtel. Much of it is based on his earlier work on the quantum hypothesis, which could not be reconciled with the accepted theory of radiation.
29. “On the Ponderomotive Forces Acting on Ferromagnetic Conductors Carrying a Current in a Magnetic Field” (Sur les forces pondéromotrices qui agissent sur des conducteurs ferromagnétiques disposés dans un champ magnétique et parcourus par un courant). Archives des sciences physiques et naturelles 30 (1910): 323–324. Einstein presented this paper to a meeting of the Swiss Society for Natural Sciences in Basel on September 6, 1910. He discusses the question of a force exerted on a ferromagnetic substance in the presence of an external magnetic field, coming up with the only expression that satisfies the principle of action equals reaction.
30. “On a Theorem of the Probability Calculus and Its Application in the Theory of Radiation” (Über einen Satz der Wahrscheinlichkeitsrechnung und seine Anwendung in der Strahlungstheorie) (with Ludwig Hopf). Annalen der Physik 33 (1910): 1096–1104. Einstein and Hopf wrote this paper to show that the failure of statistical mechanics vis-à-vis the radiation law cannot be ameliorated by proposing that individual statistical events in the emission of light from different points on the surface of a luminous body are not actually independent but instead are interdependent with each other. Even if one assumes a failure to be statistically independent, one derives the same usual form of the radiation law as Fourier sum.
31. “Statistical Investigation of a Resonator’s Motion in a Radiation Field” (Statistische Untersuchung der Bewegung eines Resonators in einem Strahlungsfeld) (with Ludwig Hopf). Annalen der Physik 33 (1910): 1105–1115. The authors make use of the results in no. 30, demonstrating that the Rayleigh-Jeans law of radiation is an unavoidable consequence of statistics, even if we avoid assumptions that we may think need correction. In other words, we cannot blame statistics for a faulty result.
32. “The Theory of the Opalescence of Homogeneous Fluids and Liquid Mixtures near the Critical State” (Theorie der Opaleszenz von homogenen Flüssigkeiten und Flüssigkeitsgemischen in der Nähe des kritischen Zustandes). Annalen der Physik 33 (1910): 1275–1298. Einstein explains the optical effects that occur near the critical point of a fluid (at which liquid and gas phases can coexist) and of a binary mixture of liquids that can also explain the blue color of the sky. It adds to earlier studies that provided evidence for the atomistic constitution of matter and is one of his most difficult papers to understand.
33. “A Relationship between Elastic Behavior and Specific Heat in Solids with a Monatomic Molecule” (Eine Beziehung zwischen dem elastischen Verhalten und der spezifischen Wärme bei festen Körpern mit einatomigem Molekül). Annalen der Physik 34 (1911): 170–174. Einstein adds a comment on p. 590 of the same journal. To supplement Sutherland’s observation that infrared eigenfrequencies of solid bodies possibly originate in the elastic vibrations of these bodies, Einstein adds that electrically charged ions are the source of optical vibrations while the mutual motions of the entire molecule cause elastic vibrations.
34. “Elementary Observations on Thermal Molecular Motion in Solids” (Elementare Betrachtungen über die thermische Molekularbewegung in festen Körpern). Annalen der Physik 35 (1911): 679–694. Here Einstein continues the work he had begun in 1907 on the specific heat of solids, where the heat agitation of solids was reduced to a monochromatic oscillation of the atom, and the specific heat was determined based on the quantum treatment of an oscillator in a radiation field. He explains the discrepancies between his formula and the measurements at low temperatures.
35. “On the Influence of Gravitation on the Propagation of Light” (Über den Einfluß der Schwerkraft auf die Ausbreitung des Lichtes). Annalen der Physik 35 (1911): 898–908. Einstein returns to his thoughts on gravitation and discusses his ideas on the static gravitational field, advancing the “half-shift” prediction of the deflection of light by a massive body such as the Sun. In his early papers on the subject (see also nos. 37 to 39), he used two important features: the principle of equivalence, and the role of the speed of light. In this paper he takes a broader perspective, saying that if a light beam is bent in an accelerating frame of reference, then (if the theory is correct) it must also be bent by gravity by exactly the equivalent amount.
36. “The Theory of Relativity” (Die Relativitätstheorie). Naturforschende Gesellschaft in Zürich. Vierteljahrsschrift 56 (1911): 1–14. A statement on the light quantum hypothesis was added in part 2 of the Gesellschaft’s Sitzungsberichte of 1911, p. xvi. Einstein presented this paper at a meeting of the Zurich Society for Natural Sciences in January as a farewell lecture after resigning from the University of Zurich to go to Prague. For the first time, he used the term “relativity theory” in a paper, having felt earlier that “relativity principle” was a more accurate description. In the exposition of the concepts and principles of special relativity, this paper is similar to no. 27, though it is less technical.
1912
37. “Thermodynamic Proof of the Law of Photochemical Equivalence” (Thermodynamische Begründung des photochemischen Äquivalentgesetzes). Annalen der Physik 37 (1912): 832–838. A supplement was published in vol. 38 (1912): 881–884. Einstein presents a continuation of his earlier work on the interaction between light and matter and on photochemical processes. It contrasts with earlier work in that it makes no use of the quantum hypothesis. He demonstrates how what he calls “the law of photochemical equivalence” is deducible by purely thermodynamical arguments if one makes certain plausible assumptions. He wrote a supplement to the paper five months later in the same journal.
38. “The Speed of Light and the Statics of the Gravitational Field” (Lichtgeschwindigkeit und Statik des Gravitationsfeldes). Annalen der Physik 38 (1912): 355–369. Further exploring his studies of gravitation, based on the equivalence principle, Einstein sees with growing clarity that gravitation is intimately linked with the problem of the measurement of space and time.
39. “On the Theory of the Static Gravitational Field” (Zur Theorie des statischen Gravitationsfeldes). Annalen der Physik 38 (1912): 443–458. Einstein more closely analyzes the equations of motion stated in no. 38, concluding that those equations cannot be reconciled with the given field equations for c (the speed of light, which played the role of the gravitational potential in this theory) because the principle of “action equals reaction” is violated. He modifies the field equation for c. The paper has the first rudimentary statement of the “law of the geodesics,” which became important for the final formulation of the gravitation theory.
40. “Is There a Gravitational Effect Which Is Analogous to Electrodynamic Induction?” (Gibt es eine Gravitationswirkung, die der elektrodynamischen Induktionswirkung analog ist?). Vierteljahrsschrift für gerichtliche Medizin und öffentliches Sanitätswesen 44 (1912): 37–40. This paper shows Einstein’s first steps in going beyond his static theory as he proceeded systematically from the special to the more general theory of relativity. In discussing the possibilities of effects of a gravito-magnetic nature, he introduced Mach’s principle—that the inertia of matter is the result of the gravitational interactions between particles—into his program for general relativity. The paper appeared in a journal of forensic medicine because it was intended for a Festschrift celebrating the founding of an institute of forensic medicine at the University of Zurich to which his friend Heinrich Zangger had been appointed director.
1913
41. “Thermodynamic Deduction of the Law of Photochemical Equivalence” (Déduction thermodynamique de la loi de l’équivalence photochimique). Journal de physique 3 (1913): 277–282. This is a published version of a lecture Einstein gave to the French Physics Society at the end of March, dealing with the topics covered in the supplement to the 1912 paper, “Thermodynamic Proof of the Law of Photochemical Equivalence.”
42. “Some Arguments for the Assumption of Molecular Agitation at Absolute Zero” (Einige Argumente für die Annahme einer molekularen Agitation beim absoluten Nullpunkt” (with Otto Stern). Annalen der Physik 40 (1913): 551–60). In this paper, Einstein and Stern show that the quantum theory of solids, to give the best agreement with experiments at normal temperatures, seems to demand that at absolute zero a residual energy would remain in the solids, which they term “zero-point energy.” They thus introduced this important concept to physics.
43. “Max Planck als Forscher” (Max Planck as Scientist). Die Naturwissenschaften 1 (1913): 1077–1079. Einstein wrote of German physicist Planck as an artist as well as a scientist, explaining that his scientific achievements show artistic creativity. He would speak about Planck again in 1918 on Planck’s sixtieth birthday, and upon his death in 1948.
44. “On the Present State of the Problem of Gravitation” (Zum gegenwärtigen Stande des Gravitationsproblems). Physikalische Zeitschrift 14 (1913): 1249–1262. Einstein gave this lecture at the 85th meeting of the Society of German Natural Scientists and Physicians in Vienna on September 23, 1913. In addition to discussing his own work, he covers Nordström’s scalar theory, a serious competitor to Einstein’s theory. He concluded that only experience could show which of the two was correct. Further discussion by participants followed the talk.
45. Outline of a Generalized Theory of Relativity and of a Theory of Gravitation (Entwurf einer verallgemeinerten Relativitätstheorie und einer Theorie der Gravitation) (with Marcel Grossmann). Leipzig: Teubner, 1913. In this book, Einstein and Grossmann investigate curved space and curved time as they relate to a theory of gravity. They present virtually all the elements of the general theory of relativity with one striking and crucial omission: their gravitational field equations are not generally covariant. Einstein soon reconciled himself to this lack of general covariance through the hole argument, which tried to establish that generally covariant gravitational field equations would be physically uninteresting. Einstein did not adopt the correct gravitational field equations until late in 1915 in his final formulations of the general theory. In this book, Einstein contributed the part on physics, and Grossmann the part on mathematics.
1914
46. “Physical Foundations of a Theory of Gravitation” (Physikalische Grundlagen einer Gravitationstheorie). Based on a lecture given on September 9, 1913, to the 96th annual meeting of the Swiss Society for Natural Sciences in Frauenfeld. Published the following year in Naturforschende Gesellschaft in Zürich. Vierteljahrsschrift 58 (1914): 284–290. Einstein reviews the theoretical aspects of gravitation theory, using more mathematics than in the actual lecture, in which he emphasized the physical content and omitted the mathematical details.
47. “On the Present State of the Problem of Specific Heats” (Zum gegenwärtigen Stande des Problems der spezifischen Wärme). Paper presented at the first Solvay Conference, November 3, 1911. Published in 1914 in Arnold Eucken, ed., Die Theorie der Strahlung und der Quanten, 330–352. Halle, Germany: Knapp, 1914. In this report to an international congress, Einstein elaborated in detail his multifaceted ideas involving the theory of quanta.
48. “On the Foundations of the Generalized Theory of Relativity and the Theory of Gravitation” (Prinzipielles zur verallgemeinerten Relativitästheorie und Gravitationstheorie). Physikalische Zeitschrift 15 (1914): 176–180. This detailed exposition of the “hole argument” implies that the metric tensor gμυ” cannot be uniquely determined by generally covariant field equations. This argument is important in reconstructing Einstein’s early understanding of the relationship between the coordinate description of a spacetime manifold and its physical properties.
49. “On the Relativity Problem” (Zum Relativitäts-Problem). Scientia 15 (1914): 337–348. Einstein makes general references to the unsuccessful search for effects of the Earth’s motion.
50. “Contributions to Quantum Theory” (Beiträge zur Quantentheorie). Deutsche Physikalische Gesellschaft. Verhandlungen 16 (1914): 820–828. Einstein attempts to derive Planck’s radiation law and Nernst’s third law of thermodynamics in a novel manner, based entirely on thermodynamics. The proofs introduce the quantum hypothesis.
51. “The Formal Foundation of the General Theory of Relativity” (Die formale Grundlage der allgemeinen Relativitätstheorie). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1914): 1030–1085. According to John Norton (“How Einstein Found His Field Equations”), this major review article is intended to convey the full content of the 1913 “Entwurf” theory (no. 45). “The principal novelty lies in the mathematical formulation of the theory. Drawing on earlier work with Grossmann, Einstein formulated his gravitational field equations using a variation principle. Using this richer mathematical structure, Einstein offered a proof purporting to demonstrate that his theory had the maximum covariance compatible with the hole argument; that is, covariance under ‘justified’ transformations between the ‘adapted coordinate systems’ he had introduced with Grossmann.”
52. “Covariance Properties of the Field Equations of the Theory of Gravitation Based on the Generalized Theory of Relativity” (Kovarianzeigenschaften der Feldgleichungen der auf die verallgemeinerte Relativitätstheorie gegründeten Gravitationstheorie) (with Marcel Grossmann). Zeitschrift für Mathematik und Physik 63 (1914): 215–225. To increase the inner consistency of the theory expounded in nos. 45 and 51, the authors apply an action principle for the derivation of the field equations for the metric tensor gμυ”.
53. “Inaugural Lecture of Mr. Einstein” (Antrittsrede des Hrn. Einstein). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1914): 732–742. In this speech before the Prussian Academy of Sciences, Einstein thanks the members for welcoming him into an academy where he can devote himself exclusively to research. He also discusses how a theoretician conducts his work, giving relativity theory as an example.
54. “Nordström’s Theory of Gravitation from the Point of View of the Absolute Differential Calculus” (Die Nordströmsche Gravitationstheorie vom Standpunkt des absoluten Differentialkalküls) (with A. D. Fokker). Annalen der Physik 44 (1914): 321–328. Einstein and Fokker reformulate the theory of gravity proposed by Gunnar Nordström using tensor calculus. The version of Nordström’s theory presented here is thus the very first covariant metric theory to appear in the scientific literature, before the completed form of general relativity the next year.
1915
55. “Experimental Proof of the Existence of Ampère’s Molecular Currents” (with Wander J. de Haas) (in English). Koninklijke Akademie van Wetenschappen te Amsterdam. Proceedings 18 (1915–16). A German version was published earlier in Deutsche Physikalische Gesellschaft. Verhandlungen 17 (1915): 152–170. A correction to it was published on p. 203 and a comment on p. 420. Considering that Ampère hypothesized that magnetism is caused by the microscopic circular motions of electric charges, the authors propose a design to test the Dutch physicist H. A. Lorentz’s theory that the rotating particles are electrons. The aim of the experiment is to measure the torque generated by a reversal of the magnetization of an iron cylinder. Einstein wrote three papers with Wander J. de Haas on experimental work they did together on Ampère’s molecular currents known as the Einstein-De Haas effect. He immediately wrote a correction when Lorentz pointed out an error in the original paper.
56. “On the General Theory of Relativity” (Zur allgemeinen Relativitätstheorie). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1915): 778–786. An addendum was added a week later in the same journal. This important paper on general relativity, written after Einstein had abandoned his “hole argument” and was closing in again on generally covariant field equations, begins by recounting Einstein’s three-year search for the correct field equations of gravitation. He concludes that “the magic of this theory will hardly fail to impose itself on anybody who has truly undestood it; it represents a genuine triumph of the method of absolute differential calculus founded by Gauss, Riemann, Christoffel, Ricci, and Levi-Civita.”
57. “Explanation of the Perihelion Motion of Mercury from the General Theory of Relativity” (Erklärung der Perihelbewegung des Merkur aus der allgemeinen Relativitätstheorie). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1915): 831–839. Einstein gives an astronomical confirmation of general relativity by using as an example the perihelion advance of Mercury. This result convinced Einstein, and many others, that the new theory was probably correct and could supersede Newton’s long-standing theory of gravity.
58. “The Field Equations of Gravitation” (Die Feldgleichungen der Gravitation). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1915): 844–847. Dropping a previous restriction, Einstein rewrites his field equations of gravitation. In the three papers (nos. 56, 57, and this one), all published in November 1915, Einstein gave expositions of his new theory of gravitation and the mathematical generalization of the theory of relativity. He concluded that while spacetime in the special theory is geometrically flat, in the general theory it is curved and includes gravity as a determinant. The seminal paper, however, was not published until 1916 (no. 62). No. 58, however, solved a long-standing problem in astronomy and was one of the main triumphs of the general theory of relativity. It also contains the first statement of what are now known as the Einstein equations, the governing equations of the gravitational field.
1916
59. “My Opinion on the War” (Meine Meinung über den Krieg). Written in October–November 1915 but not published until the following year in Das Land Goethes 1914–1916, with two paragraphs from the manuscript omitted. Stuttgart and Berlin: Deutsche Verlags-Anstalt, 1916. Einstein wrote this statement for a volume of “patriotic commemoration” to be published by the Goethebund of Berlin in which Germans were called on to defend German culture in the midst of war. In it, Einstein declared that war was rooted in the “biologically determined aggressive tendencies of the male.” He upheld pacifism and rejected war under any circumstances.
60. “A New Formal Interpretation of Maxwell’s Field Equations of Electrodynamics” (Eine neue formale Deutung der Maxwellschen Feldgleichungen der Elektrodynamik). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1916): 184–188. Einstein reformulates Maxwell’s equations in the language of tensor calculus and in light of his recent discovery of the field equations of general relativity. Later in the year (see no. 62), he would show how, in the weak-field limit, his own field equations of gravity would bear a close resemblance to this formulation of Maxwell’s theory.
61. “Ernst Mach.” Physikalische Zeitschrift 17 (1916): 101–104. In this long eulogy for Ernst Mach, the natural philosopher who had greatly influenced him, Einstein praises him as an original thinker who has had the greatest influence on the epistemological orientation of natural scientists. His “philosophical studies sprang from his desire to find a point of view from which the various branches of science … can be seen as an integrated endeavor.”
62. “The Foundation of the General Theory of Relativity” (Die Grundlage der allgemeinen Relativitätstheorie). Annalen der Physik 49 (1916): 769–822. Published as a book in Leipzig: Barth, 1916. This long and seminal paper is the earliest complete exposition of Einstein’s general theory of relativity, giving a comprehensive account of the final version of the theory after publication of his latest revisions in the papers of November 1915. In it, he presents the tools of tensor analysis that allowed him to derive the general field equations for gravity as a property of non-Euclidean space time. For the first time, he systematically uses the term “special theory of relativity,” though he had already made reference to it in two papers of 1915 (nos. 56 and 58). In conclusion, he discusses the theory’s success in explaining phenomena such as the bending of light rays in a gravitational field, an achievement that helped to establish the superiority of general relativity over classical Newtonian theory and thereby redefined our conception of the universe.
63. “Approximative Integration of the Field Equations of Gravitation” (Näherungsweise Integration der Feldgleichungen der Gravitation). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1916): 688–696. Einstein had to retract this paper’s results on gravitational waves in 1918 because of a serious error. The paper nevertheless remains of interest because it introduces an important approximation scheme in general relativity, the linearized approximation. In this scheme, instead of pursuing the obvious comparison between the theory and Newtonian gravity, Einstein explores the analogy between his new field theory of gravity and its other model, Maxwell’s field theory of electromagnetism.
64. “Emission and Absorption of Radiation in Quantum Theory” (Strahlungs-Emission und -Absorption nach der Quantentheorie). Deutsche Physikalische Gesellschaft. Verhandlungen 19 (1916): 318–323. This work represents a major step forward in quantum theory. Here Einstein proposes to replace electromagneto-mechanical considerations with quantum-theoretical contemplations on the interaction between matter and radiation.
65. “On the Quantum Theory of Radiation” (Zur Quantentheorie der Strahlung). Physikalische Gesellschaft Zürich. Mitteilungen 18 (1916): 47–62. Also published the following year in Physikalische Zeitschrift 18 (1917): 121–128. In this paper, Einstein states that one arrives at a theory that is free of contradictions only if the elementary processes are interpreted as completely directed processes. He wrote to his friend Michele Besso on August 24, 1916, that “the derivation is purely quantized and yields Planck’s formula. In connection with this, it can be demonstrated convincingly that the elementary processes of emission and absorption are directed processes. One just has to analyze the (Brownian) motion of a molecule (in the sense of that derivation) within a radiation field.”
66. “Elementary Theory of Water Waves and of Flight” (Elementare Theorie der Wasserwellen und des Fluges). Die Naturwissenschaften 4 (1916): 509–510. Einstein had lectured on this topic, in which he proposes an airfoil design, at a meeting of the German Physical Society. When placed in a moving fluid, a body will experience a net upward force, enabling it to serve as an airfoil. In 1917, a Berlin aircraft firm tested the design, which failed. A few months before his death, Einstein admitted to Paul Ehrhardt, the test pilot, that “I have often been ashamed of my folly of those days.”
67. “Hamilton’s Principle and the General Theory of Relativity” (Hamiltonsches Prinzip und die allgemeine Relativitätstheorie). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1916): 1111–1116. Inspired by the work of Hil bert and Lorentz, Einstein derives the recently formulated field equations of general relativity from a single variational principle, an approach that came to be seen as characteristic of a well-formulated field theory.
1917
68. On the Special and the General Theory of Relativity: A Popular Account (Über die spezielle und die allgemeine Relativitätstheorie [Gemeinverständlich]). Braunschweig, Germany: Vieweg, 1917. [First English edition, trans. Robert W. Lawson: Relativity: The Special and the General Theory. A Popular Exposition, came later (London: Methuen, 1920; American edition: Henry Holt, 1920).] This book presents a popular account of relativity theory, both special and general. Finding it difficult to write at this level, Einstein felt he had no choice but to do so if his theories were to be understood. The book was intended “to give an exact insight into the theory of relativity to those readers who, from a general and philosophical point of view, are interested in the theory, but who are not conversant with the mathematical apparatus of theoretical physics.” Rather than writing elegantly, he repeated himself frequently “in the interest of clearness.” The book was a huge success, with fourteen editions appearing between 1917 and 1922—and it is still available today—with only minor revisions made in subsequent editions. Translations into other languages followed, making relativity theory known throughout the world.
69. “Cosmological Considerations in the General Theory of Relativity” (Kosmologische Betrachtungen zur allgemeinen Relativitätstheorie). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1917): 142–152. Einstein’s first paper on cosmology was published in the spring. He added a “cosmological constant” in an attempt to balance the field equations of general relativity. It enabled him to describe a universe that conformed to what he and everyone else assumed: a closed and static sphere that was coextensive with the Milky Way. His chief innovation was to propose a universe with positive overall curvature which closed in on itself so that it was finite in volume but with no boundary. All of modern cosmology can be traced back to this paper, in which Einstein applied general relativity to cosmological questions for the first time. He later rejected the cosmological constant altogether, but it nevertheless refused to die and made several comebacks. Today, it is once again at the center of cosmology with the discovery of the acceleration of the expansion of the universe. (The incident has often been referred to as the “biggest blunder” of his life, particularly by physicist George Gamow in an article in the September 1956 issue of Scientific American. In it, he claimed that Einstein used those words in his presence even though there is no other documented evidence that he felt this way. See atlantic.com, August 9, 2013.)
70. “On the Quantum Theory of Radiation” (Zur Quantentheorie der Strahlung). Physikalische Zeitschrift 18 (1917): 121–128. Besides being a penetrating analysis of the properties of photons, this paper also shows that Planck’s law for thermal radiation could be simply deduced from assumptions that conform to the basic ideas of the quantum theory of atomic structure, based on the concept of transition probabilities. Einstein boldly uses this probabilistic approach to characterize the spontaneous emission of radiation by atoms (controversial because it appeared to apply not only to ensembles, but even when an individual atom might suddenly decay). He also discusses how atoms may be stimulated to undergo decay by the presence of radiation of the correct frequency, an insight that would later inspire the development of lasers, which work by stimulated emission of light.
71. “On the Quantum Theorem of Sommerfeld and Epstein” (Zum Quantensatz von Sommerfeld und Epstein). Deutsche Physikalische Gesellschaft. Verhandlungen 19 (1917): 82–92. Einstein presents a coordinate invariant form of Epstein’s formal presentation of the Bohr-Sommerfeld quantization rules. This paper was influential in the development of quantum mechanics, as cited by both De Broglie and Schrödinger. Subsequently, it was forgotten for decades until it was revived for its insight into what are now called chaotic systems that do not obey these quantization rules. The difficult subject of quantum chaos is at the forefront of research today, where this semiclassical method of quantization is known as the Einstein-Brillouin-Keller method.
72. “Manifesto to the Europeans” (Aufruf an die Europäer) (October 1914) (with Georg Nicolai, Wilhelm Foerster, and Otto Buek). Not published until 1917 as the introduction to Nicolai’s Die Biologie des Krieges. Zurich: Orell Füssli, 1917; English edition: The Biology of War, trans. C. A. Grande and J. Grande. New York: Century, 1918. In Einstein’s widely circulated first public statement on a nonscientific topic, he responds to another manifesto in which ninety-three German intellectuals and artists had defended German military actions in Belgium at the beginning of the First World War. This countermanifesto was drafted by pacifist, physician, and professor of medicine and physiology Georg Nicolai, collectively emended and signed by Einstein, Nicolai, and the two others. (See this volume, Part III, Political Contexts, “The First World War—Manifesto to the Europeans.”)
73. “The Nightmare” (Der Angst-Traum). Berliner Tageblatt, December 25, 1917. In this short article, Einstein addresses the question of whether the compulsory secondary-school leaving exam should be abolished. Einstein was in favor of discontinuing the exam, maintaining that it does not succeed in testing a pupil’s knowledge and depends too much on short-term rote learning. He felt the exam was useless as well as harmful. See also no. 155. (See this volume, Part III, Education: Einstein’s Views.)
1918
74. “On Gravitational Waves” (Über Gravitationswellen). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1918): 154–167. Correcting errors from his first treatment of the subject (see no. 63), Einstein presents the first concrete and substantially correct theory of gravitational waves. These waves are re garded as one of the most remarkable predictions of general relativity, since they are completely absent from the traditional Newtonian theory. Observational evidence for their existence became available in 1979 from observations of the first binary pulsar, observations that confirmed the most famous result of this paper, the quadrupole formula, in which Einstein predicted the flux of gravitational wave energy from an emitting system. Only in recent times is it becoming technologically possible to search for such waves as they pass by the Earth. Several detectors designed for the purpose are currently under continuing development.
75. “On the Foundations of the General Theory of Relativity” (Prinzipielles zur allgemeinen Relativitätstheorie). Annalen der Physik 55 (1918): 241–244. Here we are given the first new presentation of the foundations of general relativity since the developments of March 1916, when Einstein gave his first systematic exposition.
76. “Motives for Research” (Motive des Forschens). In Zu Max Plancks sechzigstem Geburtstag (On Max Planck’s Sixtieth Birthday). Karlsruhe: C. F. Müllersche Hofbuchhandlung, 1918. Reprinted in Ideas and Opinions (1954). This paper was based on a lecture that Einstein delivered in Berlin as part of a special session of the German Physical Society in honor of German physicist Max Planck’s sixtieth birthday. Planck, a professor of theoretical physics at the University of Berlin, is best known for his quantum theory of 1900, which provided the basis for the modern development of atomic physics. Here Einstein uses Planck as a model scientist, whose daily efforts on behalf of science come from the heart and not from any other motivations.
77. “The Law of Energy Conservation in the General Theory of Relativity” (Der Energiesatz in der allgemeinen Relativitätstheorie). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1918): 448–459. Einstein answers criticisms of his conservation law in general relativity and the pseudotensor used to express it. He argues that an integral form of the law is appropriate, and shows that the integral of a closed system’s total energy is invariant and conserved and can be measured only far from the source. The pseudotensor played the key role in his analysis of gravitational waves. No. 74, where he uses it to derive the quadrupole formula, stands in testimony to Einstein’s successful use of this controversial quantity. No. 63, where his error lay in constructing an incorrect form of the pseudotensor, stands as a harsh warning to the careless use of this noninvariant quantity that is thus different for different observers (or different frames of reference).
78. “Dialogue about Objections to the Theory of Relativity” (Dialog über Einwände gegen die Relativitätstheorie). Die Naturwissenschaften 6 (1918): 697–702. This article on the paradoxes of the theory of relativity was written in dialogue form between Einstein and his critics.
1919
79. “Do Gravitational Fields Play an Essential Role in the Structure of the Elementary Particles of Matter?” (Spielen die Gravitationsfelder im Aufbau der materiellen Elementarteilchen eine wesentliche Rolle?). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1919): 349–356. In this published lecture to the Prussian Academy of Sciences, Einstein visualized the relations in spherical space and discussed the field equations in general relativity from the point of view of the cosmological problem and the problem of the constitution of matter. He particularly pursued the notion that the field equations of general relativity might provide an explanation for the “Poincaré stresses” believed at that time to be necessary to stabilize the electron.
80. “Immigration from the East” (Die Zuwanderung aus dem Osten). Berliner Tageblatt, December 30, 1919, morning edition, p. 2. In this article, Einstein speaks out against those who claim that Jews from Eastern Europe were responsible for Germany’s problems after the war.
1920
81. Ether and the Theory of Relativity (Äther und Relativitätstheorie). Berlin: Springer, 1920. Einstein’s lecture at the University of Leyden on the occasion of his appointment as a visiting professor summarizes his current views on the ether. He retrospectively looks at the development of his opinions on the physical properties of space, and acknowledges that though his theory of special relativity banished the luminiferous ether, his theory of general relativity had arguably introduced a new ether, the fabric of spacetime itself, which, though intangible, plays an essential role in that theory.
82. “Propagation of Sound in Partly Dissociated Gases” (Schallausbreitung in teilweise dissoziierten Gasen). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1920): 380–385. This paper on the determination of chemical reaction velocities in partly dissociated gases by using sound propagation may appear to be off the beaten track for Einstein, but he dabbled with problems of fluids (liquids and gases) throughout his life. At the time it was published, the paper did not garner much attention, but molecular acoustics later became a novel investigative tool in physical chemistry.
83. “To the ‘General Association for Popular Technical Education’” (newspaper report quoting a statement by Einstein). Neue Freie Presse, July 24, 1920, morning edition, p. 8. In this statement, solicited by the association, Einstein stresses the importance of showing to students and the public the practical applications of science and technology to everyday life. He states his belief that a technical education is equal in value to a humanistic one.
84. “My Response. On the Anti-Relativity Company” (Meine Antwort. Über die anti-relativitätstheoretische G.m.b.H.). Berliner Tageblatt, August 27, 1920, morning edition, pp. 1–2. In the popular Berlin newspaper, Einstein, after having resisted public responses on earlier provocations, repudiates the attacks that had been leveled against him and relativity theory since 1918. The final straw had been two lectures that were delivered on August 24 in the Berlin Philharmonic Hall. On this occasion, his accusers put aside any scientific criticisms and charged him with plagiarism, with being hungry for publicity, manipulating the press, conducting un-German science, and so on.
85. “Ein Bekenntnisbrief Einsteins” (A Letter of Confession by Einstein). Israelitisches Wochenblatt für die Schweiz, September 24, 1920, p. 10. The letter, intended as a private communication, was written a half-year earlier and made its way mysteriously into the press. Einstein refuses an invitation to address the Central Association of German Citizens of the Jewish Faith, mocking its elitism and stressing the need for solidarity with East European Jews. (See also this volume, Part III, Jewish Identity and Ties, “The Cultural Zionist Ideal.”)
86. Relativity: The Special and the General Theory. First English edition, 1920. See no. 68.
1921
87. “The Common Element in Artistic and Scientific Experience” (Das Gemeinsame am künstlerischen und wissenschaftlichen Erleben). Menschen. Zeitschrift neuer Kunst 4 (1921): 19. In this short statement, Einstein emphasizes that art and science have common elements in that both give expression to creativity: in science through logic, and in art through form. Both help one escape from the merely personal.
88. Geometry and Experience (Geometrie und Erfahrung). Berlin: Springer, 1921 (an expanded version of a lecture, held at the Prussian Academy of Sciences on January 27, 1921). (English version published in Sidelights in Relativity. London, Methuen, 1922.) Lecturing to a session of the Prussian Academy of Sciences commemorating Frederick the Great, Einstein discusses the special esteem mathematics receives. He sums up his views on the geometrization of physics and relativity and the relation of mathematics to the external world. He asks if human reasoning, even without direct experience, can lead to an understanding of the properties of real things merely through thought. Considering the puzzling question of why mathematics should be so well adapted to describing the external world, he concluded: “As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.”
89. “A Brief Outline of the Development of the Theory of Relativity.” Nature 106 (1920–21): 782–784. Trans. from the German manuscript by Robert Lawson. In a special issue of Nature devoted to relativity theory, Einstein and other European contributors write about the contemporary results and problems of the theory in the hope of restoring international scientific cooperation after the war. Einstein describes the sequence of ideas that led to his theory and concludes with prescient remarks on the questions that remain.
90. “How I Became a Zionist” (Wie ich Zionist wurde). Jüdische Rundschau, June 21, 1921, pp. 351–352. In an interview by the editor of the Jewish magazine, Einstein maintains that intellectuals are the propagators of anti-Semitism, that elites use anti-Semitic sentiments for political gain, but that hatred comes from those who are “primitive and uneducated” about those who are different from them. He also takes the opportunity to reiterate his indifference to Judaism as a religion.
91. “Een Interview met Prof. Albert Einstein” (An Interview with Prof. Albert Einstein). Nieuwe Rotterdamsche Courant, July 4, 1921. A translation of the Dutch original is provided in CPAE, Vol. 7, appendix D, pp. 623–625. The interview, conducted in Berlin by a Dutch correspondent after Einstein’s return from his fund-raising trip to America, provoked outrage in the United States. Perhaps most offensive was his claim that American men were “toy dogs for their wives, who spend the money in the most excessive fashion.” Realizing that he had gone too far, Einstein claimed subsequently that he had been misquoted.
92. “On a Jewish Palestine” (based on an address given by Einstein in Berlin on June 27, 1921). Jüdische Rundschau, July 1, 1921, p. 371. Einstein emphasizes the importance of Palestine as a symbol of Jewish cultural unity over its importance as a Jewish settlement; cultural unity was the basis of his support of Zionism at this time.
93. “On the Founding of the Hebrew University of Jerusalem” (Zur Errichtung der hebräischen Universität in Jerusalem”). Jüdische Pressezentrale Zürich, August 26, 1921, p. 1. In this article, Einstein supports the establishment of a university in Jerusalem and advocates an emphasis on the sciences and health professions. He feels that it is necessary for a Jewish homeland to have a university both for its own citizens as well as to give those Jews who were barred from attending other universities a place to study, teach, and conduct research. He also hopes that when such an institution gains a distinguished international reputation, Jews will no longer be inclined to hide their group identity as Jews wherever they might work.
94. “The Plight of German Science: A Danger for the Nation” (Die Not der deutschen Wissenschaft. Eine Gefahr für die Nation). Neue Freie Presse, December 25, 1921, morning edition, p. 1. See also no. 102. This statement was solicited by the editor of the paper to promote scientific interests between Germany and Austria. Fearing the collapse of scientific research due to the dismal economic conditions in Germany, Einstein appeals to wealthy private donors to supplement the government’s appropriation to a privately endowed emergency fund. He emphasizes that “the insights and methods created by science usually serve practical purposes only in an indirect way and often only for future generations.”
1922
95. “On an Experiment concerning the Elementary Process of Light Emission” (Über ein den Elementarprozeß der Lichtemission betreffendes Experiment). Königlich Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1921, but published January 5, 1922): 882–883. Einstein asserts his belief that light quanta are real by proposing an experiment that shows the breakdown of wave optics directly through a nonstatistical phenomenon rather than the statistical evidence for the quantization of light produced so far.
96. “Impact of Science on the Development of Pacifism.” German contribution to Kurt Lenz and Walter Fabian, eds., Die Friedensbewegung (The Peace Movement), 78–79. Berlin: Schwetschke, 1922. Because technical inventions that arise from science have international consequences, including military applications, men must create organizations dedicated to preventing wars whenever there is a possibility that such products might be used violently.
97. Four Lectures on the Theory of Relativity, Held at Princeton University in May 1921 (Vier Vorlesungen über Relativitätstheorie gehalten im Mai 1921 an der Universität Princeton). Braunschweig, Germany: Vieweg, 1922. (English version published by Methuen in London as The Meaning of Relativity, trans. Edwin P. Adams. See also 5th ed., pbk., Princeton Science Library. Princeton, NJ: Princeton University Press, 1988.) In 1921, during Einstein’s first trip to the United States, he gave a series of five lectures on relativity theory at Princeton University. This book is based on these lectures, though two of the lectures were combined into one for the book. It is still in print, with several revisions and additions made in later editions.
98. “On the Theory of Light Propagation in Dispersive Media” (Zur Theorie der Lichtfortpflanzung in dispergierenden Medien). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1922): 18–22. In this paper submitted to the Prussian Academy of Sciences, Einstein introduces a calculation on the topic and explains why an earlier proposed experiment of his had not been well considered because it could not predict a good choice between two theoretical alternatives.
99. “Quantum Theoretical Comments on the Experiment of Stern and Gerlach” (Quantentheoretische Bemerkungen zum Experiment von Stern und Gerlach) (with Paul Ehrenfest). Zeitschrift für Physik 11 (1922): 31–34. The two physicists show that the Stern-Gerlach effect, discovered in 1922, has to overcome insurmountable difficulties if it is to show the behavior of atoms in a magnetic field. It poses a problem that cannot be solved using contemporary quantum theory. The authors anticipated what would later become the quantum measurement problem.
100. “On the Present Crisis of Theoretical Physics” (Über die gegenwärtige Krise der theoretischen Physik). Kaizō 4 (December 1922), no. 12: 1–8. After reviewing how the scientific system of concepts used in theoretical physics developed and grew, Einstein writes that the foundations of physics will demand fundamental changes in order to continue advancing the field.
101. “How I Created the Theory of Relativity” (Wie ich die Relativitätstheorie entdeckte). Lecture at University of Kyoto, Japan, December 14, 1922. (Notes taken by Yun Ishiwara and translated into English by Y. A. Ono in Physics Today, August 1932, p. 45.) In this informal lecture delivered during his trip to Japan, Einstein reflects on his path to relativity theory. Japanese physicist Yun Ishiwara kept notes of the lecture and published them in 1923 in Kyoto, where they were reprinted in 1971. The 1932 translation by Ono in Physics Today refreshed Einstein’s memory later in life about this important part of his scientific journey.
102. “The Peril to German Civilisation.” New Leader 1 (1922): 11. Einstein answers questions about the German economy, posed by the editor of the bimonthly opinion magazine. He is concerned mainly about the reduction of salaries for teachers and other intellectual workers (or “brain workers,” as he refers to them) due to German war debts. He fears that the middle class is losing ground and may fail to reach its potential.
1923
103. “Musings on My Impressions in Japan.” Kaizō 5 (1923): 338–343. In this article, in which Einstein pauses to reflect on his trip to Japan, he clearly shows his enchantment with the country and the Japanese people. He observes that the land is “shrouded in a veil of mystery,” that everything that is native to Japan is “delicate and joyful” and connected to nature. He later wrote his son Hans Albert that the Japanese were “better than all the people I’ve met up to now: quiet, modest, intelligent.”
104. “On the General Theory of Relativity” (Zur allgemeinen Relativitätstheorie). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1923): 32–38 (note appended on 76–77). Written in January 1923 aboard the Haruna Maru on his return trip from Japan to Berlin, in this document Einstein searches for a unified theory of gravitation and electromagnetism, which would dominate his scientific thinking until his death.
105. “My Impressions of Palestine.” New Palestine 4 (1923): 341. Einstein recounts the experiences and feelings he encountered during his visit to the future Jewish state. He was not yet concerned about an “Arab question,” declaring that Jews and Arabs appeared to live in harmony, and that the major problems were those of sanitation, malaria, and debt. By the end of the decade, after major anti-Jewish disturbances, he became more concerned about the Arabs and their grievances.
106. “Fundamental Ideas and Problems of the Theory of Relativity” (Grundgedanken und Probleme der Relativitätstheorie). In Nobelstiftelsen: Les prix Nobel en 1921–1922. Stockholm: Imprimèrie Royale, 1923. This paper presents Einstein’s Nobel Lecture delivered in Gothenburg, Sweden, on July 11, 1923. Because he did not deliver the lecture at the time of the award, it did not discuss the major prize topic—the discovery of the photoelectric effect—and surveyed relativity theory instead.
107. “Does Field Theory Offer Possibilities for Solving the Quanta Problem?” (Bietet die Feldtheorie Möglichkeiten für die Lösung des Quantenproblems?). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1923): 359–364. Einstein writes that despite great successes in quantum theory for a quarter of a century, there is still no logical foundation for the theory, and one must question whether the remaining difficulties could be overcome by the consistent development of earlier theories.
1924
108. “The Compton Experiment” (Das Komptonsche Experiment). Berliner Tageblatt, April 20, 1924, suppl., p. 1. Einstein discusses Arthur Compton’s discovery of 1922 that an X-ray’s wavelength is increased when incident radiation is scattered by free electrons, implying that the scattered quanta have less energy than the quanta of the original beam. This effect, now known as the Compton effect, clearly illustrates the particle concept of electromagnetic radiation. Compton received the Nobel Prize in physics in 1927 for this discovery.
109. “On the One-Hundredth Anniversary of Lord Kelvin’s Birth” (Zum hundertjährigen Gedenktag von Lord Kelvins Geburt). Naturwissenschaften 12 (1924): 261–267. The work of Lord Kelvin (William Thomson) was based in its entirety on the fundamentals of Newtonian mechanics. Einstein recounts its influence on other researchers, such as James Clerk Maxwell. Instead of giving an overview of Thomson’s life, he gives a few examples of the scientist’s work that he finds particularly appealing.
110. “Quantum Theory of the Monatomic Ideal Gas” (Quantentheorie des einatomigen idealen Gases). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1924): 261–267. Other treatises on the subject were published in the same journal (1925): 3–14 and 18–25. Einstein responds to the work of the Indian physicist Satyendra Bose, whose paper he himself had submitted to the Zeitschrift für Physik, at Bose’s request, to ensure its publication. He envisions a penetrating analogy between the properties of thermal radiation (the subject of Bose’s paper, which re-derives the Planck law for thermal radiation from more elementary statistical considerations) and gases of the “degenerate state.”
1925
111. “Mission of Our University.” New Palestine 8 (1925): 294. As a new member of the governing board of the Hebrew University of Jerusalem, Einstein outlines the goals of the newly established university for which he had helped raise funds.
112. “Unified Field Theory of Gravitation and Electricity” (Einheitliche Feldtheorie von Gravitation und Elekrizität). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1925): 414–419. This was Einstein’s first paper that used the term “unified field theory” in the title. It was also the beginning of his own long series of papers on this subject, in the sense that his earlier papers on the topic had largely been investigations of the proposals of others, including Hermann Weyl, Theodor Kaluza, and Arthur Stanley Eddington. Here he proposes to base his unified field on the affine connection as well as the metric, with both entities permitted to be asymmetric (in general relativity the fundamental quantity is the metric, which must be symmetric). He saw the asymmetric part of the resulting field as being the representative of electromagnetism, but had only limited success in demonstrating his point. He eventually returned to the theory in the last decade of his life.
113. “The Electron and General Relativity” (Elektron und Allgemeine Relativitatstheorie). Physica 5 (1925): 330–334. In parallel with the unified field theory program begun in no. 112, this paper is an early example of a series of papers—which continued until his death—in which he explored, within the confines of general relativity, possible pathways in the direction of a unified field theory. Here he discusses whether it is possible to explain why electrons and protons have equal charge but unequal masses. He notes that a more natural solution to the field equations would be particles of opposite sign and equal mass, thus anticipating (but for unrelated reasons) the later prediction and discovery of the positron.
114. “Quantum Theory of the Ideal Gas” (Quantentheorie des idealen Gases). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte n.v. (1925): 18–25. Having observed that the ideas of the Indian physicist Satyendra Bose are based on the idea of a photon gas, that is, they are based on an analogy between the statistical behavior of photons and those of atoms in an ideal gas, Einstein turns the analogy around. He applies Bose’s insight about photons (that they are indistinguishable particles) to the case of monatomic ideal gases. In doing so, he is led to the famous prediction of the Bose-Einstein condensation effect and one of the earliest statements of wave properties in particles of matter.
1926
115. “On the Cause of the Formation of Meanders in the Courses of Rivers …” (Über die Ursache der Mäanderbildung der Flussläufe und des sogenannten Baerschen Gesetzes). Naturwissenschaften 14 (1926): 223–334. English translation in Ideas and Opinions (1954). Read first before the Prussian Academy of Sciences on January 7, this paper discusses why the erosion of rivers tends to take place on the right bank in the Northern Hemisphere and on the left in the Southern. Having found no one who was thoroughly familiar with the causal relations involved, Einstein decided to tackle the problem himself. He explains that Earth’s rotation produces the Coriolis force (operating with a different handedness in the two hemispheres of the world), which is reduced toward the bottom of a river and gives rise to a circular movement in the riverbed. A turbulent distribution of velocities in the bed is developed and maintained and causes erosion. See Illy, The Practical Einstein, pp. 10–14, for a discussion of research on meandering conducted before and after Einstein’s short paper.
116. “Interference Characteristics of Light Emitted by Canal Rays” (Über die Interferenzeigenschaften des durch Kanalstrahlen emittierten Lichtes). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1926): 334–340. This article appeared in conjunction with an experimental report by Emil Rupp based on the experimental design described here by Einstein. The status of Rupp’s experiments based on Einstein’s ideas was later cast into doubt when, in 1935, Rupp was forced to retract five of his recent papers after colleagues showed that Rupp did not even possess the apparatus to have carried out the experiments reported in them. It is now generally believed that all of Rupp’s experiments, including those reported to Einstein in an extensive correspondence, were fraudulent. Einstein never visited Rupp’s laboratory, as he would normally have done, to observe the experiments, because he was by then totally estranged from Rupp’s supervisor, Philipp Lenard.
117. “On Kaluza’s Theory on the Connection between Gravitation and Electricity” (Zu Kaluzas Theorie des Zusammenhanges von Gravitation und Elektrizität). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1927): 23–35. Kaluza attempted to unify Einstein’s theory of gravity with Maxwell’s theory of light by mixing them in a fifth dimension. In 1926, the theory received renewed attention when the mathematician Oskar Klein described how the apparently spurious fifth dimension could be real but unobservable because it was curled up upon itself (“compactified”) so that motion in that direction was insensible to us. The theory in this form is usually referred to as the Kaluza-Klein theory.
118. “Newton’s Mechanics and Its Influence on the Shaping of Theoretical Physics” (Newtons Mechanik und ihr Einfluß auf die Gestaltung der theoretischen Physik). Naturwissenschaften 15 (1927): 273–276. English translation in Ideas and Opinions (1954). Writing on the occasion of the two-hundredth anniversary of Newton’s death, Einstein traces the historical development of physics, from the Greeks to Galileo to Newton and the present time, especially emphasizing Newton’s contributions.
119. “Isaac Newton.” Letter to the Royal Society on the 200th anniversary of Newton’s death. Nature 119 (1927): 467. In this letter, Einstein praises the British for their traditions and for providing an atmosphere that allows the human soul “to soar.” Everything that has happened in theoretical physics since Newton’s time developed from his ideas, and only in quantum theory has Newton’s differential method been inadequate.
120. “General Theory of Relativity and the Laws of Motion” (Allgemeine Relativitätstheorie und Bewegungsgesetze). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1927): 235–245. Einstein attacks the problem of deducing the law of motion from the field equations. He repeatedly returned to this problem in his later work.
1928
121. “Riemannian Geometry with Preservation of the Concept of Distant Parallelism” (Riemanngeometrie mit Aufrechterhaltung des Begriffes des Fern-Parallelismus). Preußische Akademie der Wissenschaften (Berlin), Sitzungsberichte (1928): 217–221. See next paper.
122. “New Possibilities of a Unified Field Theory of Gravitation and Electricity” (Neue Möglichkeiten für eine einheitliche Feldtheorie von Gravitation und Elektrizität). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1928): 224–227. Nos. 121 and 122 discuss Einstein’s concept of a unified field theory based on what he referred to as distant parallelism, an idea that came to Einstein during a period of bed rest due to ill health. The mathematical formalism for this theory had, unknown to Einstein, been previously developed by the mathematician Elie Cartan and is today known as Einstein-Cartan theory or “torsion” theory. The “torsion” element of the theory, which mathematically describes an antisymmetric component of the affine connection (or distant parallelism), is considered interesting because of the possibility that it might provide an explanation of the intrinsic spin of elementary particles.
123. “H. A. Lorentz.” Mathematisch-naturwissenschaftliche Blätter 22 (1928): 24–25. Reprinted as “Address at the Grave of H. A. Lorentz” in Ideas and Opinions (1954), 73. In this eulogy at the grave of the Dutch theoretical physicist whom Einstein admired and loved, Einstein calls him the “greatest and noblest man of our time.”
1929
124. “On the Unified Field Theory” (Zur einheitlichen Feldtheorie). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1929): 2–7. This exposition of Einstein’s theory on unitary field laws for gravitation and electromagnetism (unified field theory, or UFT) focuses on his efforts to find a set of field equations for the distant parallelism approach introduced in nos. 121 and 122. The publication of this paper was immediate news. Ongoing gossip in the mass media had claimed that Einstein had solved the riddle of the universe, and this publication was highly anticipated. The first printing sold out immediately, and the publisher ordered more printings. Einstein could not understand the commotion, even though he had faith in his theory. Critics found fault with it, however, and after a few more attempts at corrections over the following couple of years, Einstein abandoned the distant parallelism approach and returned to a new variant of the Kaluza-Klein theory influenced by his experiences with the current method.
1930
125. “About Kepler” (Über Kepler). Frankfurter Zeitung, November 9, 1930. English translation in Ideas and Opinions (1954). Writing on the occasion of the three-hundredth anniversary of Johannes Kepler’s death, Einstein recounts the difficulties Kepler must have faced while working on planetary motion, and he praises the ingenious methods Kepler used. He concludes that “knowledge cannot spring from experience alone but from the comparison of the inventions of the intellect with observed fact.”
126. “Religion and Science.” New York Times, November 9, 1930. Reprinted in Ideas and Opinions (1954), 36–40. Einstein wrote this article expressly for the New York Times Magazine. In this somewhat provocative piece, he professes his belief in a “cosmic religion,” which to him is a higher level of religion than organized religion. He declares that it is a “miraculous order that manifests itself in all of nature as well as in the world of ideas,” and it is devoid of a personal God who rewards and punishes people based on their behavior. He concludes that there is no conflict between science and religion, that indeed cosmic religiosity is necessary for scientific research. (See also this volume, Part III, Religion.)
127. “Science and God: A Dialogue.” Forum and Century 83 (1930): 373–379. This article is based on a conversation with J. Murphy and J.W.N. Sullivan, touching on the relationship of science to other aspects of life, the question of Jewish racial characteristics, and other topics of interest to Einstein. Sullivan was a mathematician and science popularizer who had undertaken a “tour of great men,” interviewing as many eminent scientists as he could find for an upcoming book. James Murphy was an Irish writer, lecturer, and conversationalist.
128. “What I Believe.” Forum and Century 84 (1930): 193–194. Reprinted as “The World as I See It” in Ideas and Opinions (1954), 8–11. Here Einstein puts forth his personal beliefs and philosophy. This piece contains his well-known quotations, “I have never looked upon ease and happiness as ends in themselves—such an ethical basis I call the ideal of a pigsty…. The ideals which have guided my way … have been Kindness, Beauty, and Truth,” and “The most beautiful experience we can have is the mysterious.” See also frontmatter of this volume.
1931
129. “Science and Happiness.” Speech at California Institute of Technology. Reprinted in New York Times, February 22, 1931, sec. 9, 2:1. Also published in Science, n.s., 73, no. 1893 (April 10, 1931): 375–381. Einstein rhetorically asks why science has brought so little happiness, and answers: we have not yet learned to make sensible use of it. Scientists must not forget that concern for people’s happiness is paramount in all technical endeavors.
130. “Militant Pacifism.” World Tomorrow 14 (1931): 9. Reprinted in Ideas and Opinions (1954) as “Active Pacifism.” Einstein made these remarks in response to a peace demonstration in Flemish Belgium, calling for disarmament and hoping that future generations “will look back on war as an incomprehensible aberration of their forefathers.”
131. “The Nature of Reality.” Modern Review (Calcutta) 49 (1931): 42–43. In this conversation, Einstein and Indian musician and poet Rabindranath Tagore discuss the nonmaterial world. This first conversation between the two Nobel laureates took place on July 14, 1930, in Einstein’s summer home in Caputh, near Berlin. They discuss humankind’s place in the world, and the nature of truth, reality, religion, and beauty.
132. “Tagore Talks with Einstein.” Asia 31 (1931): 138–142. This second conversation between Einstein and Tagore took place on August 19 in the home of mutual friends, the Mendels, in Berlin. They discuss freedom, determinism, psychology, and philosophical issues but focus on the differences between Eastern and Western music.
133. “The 1932 Disarmament Conference.” Nation 133 (1931): 300. Reprinted in Ideas and Opinions (1954). After declaring that the state should be the servant of man and not vice versa, Einstein discusses the need for international disarmament, abolishment of compulsory military service, and changes in educational systems that hand down military traditions. He decries nationalism as unhealthy because it leads to aggression and war, and calls for the protection of conscientious objectors worldwide. He optimistically believes that dutiful national leaders “do, in the main, honestly desire to abolish war.”
134. “On the Cosmological Problem of the General Theory of Relativity” (Zum kosmologischen Problem der allgemeinen Relativitätstheorie). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1931): 235–237. In this paper, Einstein accepts the nonstatic character of the universe and rejects the cosmological constant as unnecessary and as compromising the simplicity of his field equations. See also the discussion under no. 69. He wrote this paper in response to the discovery of the expansion of the universe by Edwin Hubble. We now know that Einstein’s initial response to this discovery was to begin a paper in which he tried to replace his static universe with a stationary one that is similar to the steady-state universe of the postwar period. In the latter model, the universe did expand (in the sense that individual galaxies will continue to become more distant from one another) but would never change its appearance because new matter created in the space between galaxies would lead to the creation of new galaxies, preserving the density of galaxies in spite of the expansion. He abandoned this approach, however, and accepted that the expansion was not only real, but was changing the universe with time.
135. “Unified Theory of Gravitation and Electricity” (Einheitliche Theorie von Gravitation und Elektrizität), part 1 (with Walther Mayer). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1931): 541–557. See no. 138 for part 2. In this paper, Einstein once again changes tack in his search for a unified field theory, returning to the five-dimensional approach of the Kaluza-Klein theory but marrying it to an aspect of his work on distant parallelism. In those papers (see nos. 121 and 122), he had introduced a tetrad of vectors at each point in space whose properties were central to the theory. He now adds a vector to the tetrad, making five vectors instead of four.
1932
136. “To American Negroes.” Crisis 39 (1932): 45. Writing for the NAACP’s official journal, Einstein criticizes racism after he witnessed rampant racial prejudice during his visit to the United States in the winter of 1931–1932.
137. “Is There a Jewish View of Life?” Opinion 2 (September 26, 1932): 7. Reprinted in Ideas and Opinions (1954). In answer to this question, Einstein writes that in his opinion there is no specific Jewish point of view. He believes, however, that the Jewish tradition has a reverence for life and a positive attitude toward it, and contains “a sort of intoxicated joy and amazement at the beauty and grandeur of this world.”
138. “Unified Theory of Gravitation and Electricity” (Einheitliche Theorie von Gravitation und Elektrizität), part 2 (with Walther Mayer). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1932): 130–137. See no. 135 for part 1. Although this new version of the Kaluza-Klein theory had some formal success in terms of one of the goals of Einstein’s UFT program—reproducing the field equations of gravitation and electricity—it failed in terms of his other two goals. It did not seem to permit solutions to its equations that would correspond to (and provide some explanation for the existence of) observed elementary particles, such as the electron and the proton, nor did it offer any insights into the quantum problem. After attempting to address these two issues in this paper, Einstein once again drops this approach and turns to a new one.
139. “Semivectors and Spinors” (Semi-Vektoren und Spinoren) (with Walther Mayer). Preußische Akademie der Wissenschaften (Berlin). Sitzungsberichte (1932): 522–550. In this paper, Einstein and his assistant Mayer address the introduction into physics, by Paul Dirac and others, of the concept of the spinor. (The term was coined by Einstein’s friend Paul Ehrenfest, who drew Einstein’s attention to this problem.) Einstein tries to show that constructs of his own invention, called semivectors, would do the work of spinors in what he felt was a mathematically more natural way.
140. “On the Relation between the Expansion and the Mean Density of the Universe” (with Willem de Sitter). Proceedings of the National Academy of Sciences (USA) 18 (1932): 213–214. Einstein and de Sitter present a revised cosmological model that solves the Friedmann equations and takes account of Edwin Hubble’s proof of the expansion of the universe. They attempt to incorporate newly available estimates of the mean density and rate of expansion of the system of galaxies, and show that they are consistent with the hypothesis that the universe is geometrically flat. With these assumptions, they find that the cosmological constant is no longer necessary. Einstein left it to others to pursue the implications of this type of cosmology, which would lead to the Big Bang theory.
141. “Introduction and Address to Students of UCLA,” February 1932. In Builders of the Universe. Los Angeles: U.S. Library Association, 1932. In this little-known text, presented in both English and German, Einstein discusses the source of his own creative scientific work. The subject is science as a coordination of observed facts, as seen, for example, in the progression from the special theory of relativity to the unified field theory.
1933
142. Why War? Trans. Stuart Gilbert. Paris: International Institute of Intellectual Cooperation, League of Nations, 1933. This short pamphlet consists of an exchange of letters between Einstein and Sigmund Freud on the proclivity of humankind to make war, and what can be done to counter it. (See also this volume, Part III, Political Contexts, “The First World War—‘Why War?’”)
143. “Letter to the Prussian Academy of Sciences.” Science, new ser. 77 (1933): 444. In this letter of April 5, 1933, Einstein states his reasons for resigning from the Prussian Academy of Sciences (he had resigned in a letter of March 28): he does not wish to live “in a state in which individuals are not granted equal rights before the law as well as freedom of speech and teaching.” He expressed the opinion that the academy had slandered him by accusing him in America and France of “atrocity-mongering” against Germany.
144. “Victim of Misunderstanding.” The Times (London), September 16, 1933, p. 12. In this letter, Einstein explains his position on communism. He admits that he has been negligent in permitting Communist-front organizations to use his name and writes that he “would now like to state that I have never favoured Communism and do not favour it now…. Any Power must be the enemy of mankind which enslaves the individual by terror or force, whether it arises under a Fascist or Communist flag.”
145. “Civilization and Science.” Speech presented at Royal Albert Hall, London, October 4, 1933. Published as “Europe’s Danger, Europe’s Hope” in 1934 by Friends of Europe Publications, no. 4. The meeting was organized by the Refugee Assistance Fund. Einstein spoke on the interrelationship between personal freedom and collective security and concluded that “only through peril and upheaval can nations be brought to further development.”
146. “On the Method of Theoretical Physics.” Herbert Spencer Lecture at Oxford University, June 10, 1933. Oxford: Clarendon, 1933. Reprinted in Ideas and Opinions (1954). In this lecture series in honor of philosopher Herbert Spencer, Einstein speaks about the development of the theoretical system, “something ineffable about the real, something occasionally described as mysterious and awe-inspiring,” and the function of pure reason in science. He maintains that pure thought can grasp reality, using mathematical concepts to justify his confidence.
147. “The Two Percent Speech,” in Lief, ed., The Fight Against War, pp. 34–37. The speech was delivered three years earlier, at a time when Einstein still hoped that “uncompromising war resistance” by individuals might prevail against the military juggernaut. Hitler’s seizure of power at the beginning of 1933 put an end to this illusion. (See also this volume, Part III, Political Philosophy, “Pacifism.”)
148. “Notes on the Origin of the General Theory of Relativity.” George A. Gibson Foundation Lecture at Glasgow University, June 20, 1933. Glasgow University Publications, no. 20. Glasgow: Jackson, 1933. Reprinted in Ideas and Opinions (1954) as “Notes on the Origin of the General Theory of Reltivity.” The sponsors of the lecture asked Einstein to speak about the history of his own scientific work. He agreed to the invitation because “it is easier to throw light on one’s own work than on some one else’s,” and one should not neglect to do so out of modesty. He discusses the work of others who had influenced him and which eventually led to his discoveries, and outlines the obstacles he had to overcome in his own thinking.
1934
149. The World as I See It (Mein Weltbild). New York: Covici-Friede, 1934. This book is a collection of excerpts and essays on a variety of topics, the first of several future editions. Later editions were abridged and do not contain some of the material in this original version. Among other essays, it includes Einstein’s lectures at King’s College in London and at Columbia University in New York, both given in 1921, and a number of writings on science, Judaism, and politics. Many of these essays and lectures are reprinted in Ideas and Opinions (1954).
150. “Education and World Peace.” Progressive Education 11 (1934): 440. In this message, read at a New York conference of the Progressive Education Association on November 23, 1934, Einstein says that the United States is in the fortunate position of teaching pacifism in the schools because, due to “no serious danger” of a foreign invasion, it is unnecessary to inculcate a military spirit in pupils. He calls for international rather than national military means of defense and a strengthening of international solidarity.
1935
151. “Peace Must Be Waged.” Interview by R. M. Bartlett. Survey Graphic 24 (1935): 384. Einstein offers his view on war and peace in this interview, dealing mainly with Germany’s nationalism since the First World War. He advocates the following: every country should surrender a portion of its sovereignty through international cooperation; populations need to think in international terms; and, to avoid wholesale destruction, nations must sacrifice aggression. He also states his belief that humans can abolish war through education.
152. “Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?” (with B. Podolsky and N. Rosen). Physical Review, ser. 2, 47 (1935): 777–780. Here the authors bring to public attention Einstein’s critical attitude toward quantum theory. They elegantly expose the consequences of the quantum-mechanical formalism regarding the representation of a state of a system that consists of two parts that have been in interaction for a limited time interval. If the two particles are in what is now called an “entangled” quantum state, then a measurement of one will instantaneously result in a change in the quantum state of the other, in apparent violation of the relativistic prohibition against information traveling faster than the speed of light (what is sometimes referred to as “spooky action-at-a-distance”). According to the authors’ criteria, they conclude that quantum mechanics does not provide a complete description of physical reality, allowing Einstein and others to adhere to the classical framework or to continue to search for some neoclassical theory that could account for quantum phenomena (such as hidden-variable theories). This paper created contention among physicists and was the basis for many philosophical discussions. It raises issues that later became a major focus for research in the theory of quantum decoherence and lie at the heart of modern quantum computing technology. Although the article is said to have been written by Podolsky (after intense discussions with Einstein), it nevertheless articulates one of Einstein’s core beliefs about quantum mechanics: that its inability to disentangle the future behavior of particles in certain states meant that it gave, as he put it, an incomplete description of the world.
153. “Elementary Derivation of the Equivalence of Mass and Energy.” J. W. Gibbs Lecture of the American Mathematical Society delivered at Carnegie Tech, now Carnegie-Mellon University, in Pittsburgh, December 28, 1934. Bulletin of the American Mathematical Society 41 (1935): 223–230. In this highly technical lecture to mathematicians and physicists, Einstein establishes, among other things, the definition of relativistic momentum and relativistic energy without using electromagnetic theory.
154. “The Particle Problem in the General Theory of Relativity” (with Nathan Rosen). Physical Review, ser. 2, 48 (1935): 73–77. This paper explores possible representations of elementary particles within the general theory of relativity and thus forms a part of Einstein’s unified field theory program. It is notable for the introduction of the Einstein-Rosen bridge, now called a wormhole, which is a geometrical construction that connects two otherwise distant points in spacetime. Although intended by Einstein and Rosen as a particle model, it has become well known in recent times for its possible role as a rapid means of transport from one place to another, or even as a possible means of constructing time machines (known as “closed timelike curves” in the jargon of the field).
1936
155. “Some Thoughts concerning Education.” Trans. Linda Arronet. School and Society 44 (1936): 589–592. Reprinted in Ideas and Opinions (1954) as “On Education.” See also no. 73. (See this volume, Part III, Education: Einstein’s Views.) In this speech, given at a State University of New York at Albany convocation to celebrate the tercentenary of higher education in America, Einstein maintains that the aim of education must be to train independently thinking individuals. Their highest goal in life should be to serve their communities. Schools should not educate by fear, force, and arbitrary authority—all of which he had detested in the German educational system of his youth.
156. “Physics and Reality.” Journal of the Franklin Institute 221, no. 3 (March 1936): 313–347. Reprinted in Ideas and Opinions (1954). Einstein, who was awarded the Franklin Medal in 1935, argues that the quantum-mechanical description can be considered only as a way to account for the average behavior of a large number of atomic systems. He expresses his belief that it should give exhaustive descriptions of indi vidual phenomena: “To believe this [that individual elementary particles can be governed only by statistical laws, rather than deterministically] is logically possible without contradiction, but it is so very contrary to my scientific instinct that I cannot forgo the search for a more complete conception.”
157. “Two-Body Problem in General Relativity Theory” (with Nathan Rosen). Physical Review (ser. 2), 49: 404–405. This letter was written in reply to an article by Ludwik Silberstein, a prominent opponent of relativity within the physics community. Unlike many anti-relativists, Silberstein understood the theory and knew Einstein personally. He seized on Einstein and Rosen’s previous paper (no. 154) to argue that the two ends of the Einstein-Rosen bridge were two separate particles whose failure to move closer to each other represented a violation of what we know about gravity. In this reply, Einstein and Rosen observe that the system contains singularities so that it cannot be taken as a dynamical physical system for Silberstein’s purposes.
158. “Lens-like Action of a Star by Deviation of Light in the Gravitational Field.” Science 84: 506–507. This short note gives an interesting example of Einstein’s ability to recognize important insights in the work of outsiders, even amateur scientists, such as a Czech engineer named Rudi W. Mandl. Mandl came to Einstein in April 1937 to propose the germ of the idea that we call gravitational lensing today. Mandl had already fruitlessly contacted a number of scientists with his ideas—no doubt they were repelled by some of the fantastical elements, such as the notion that lensing of this type might have caused the extinction of the dinosaurs—but Einstein spent time with him. Together they realized that a foreground star will, through the gravitational deflection of the light from another star standing directly behind it, increase the apparent brightness of the more distant star, making it easier to see. Einstein, prompted by Mandl, performed calculations to estimate the size of the effect and concluded that it would never be seen in the case of stars because of the brightness of the foreground star. Nevertheless, at Mandl’s persistent urging, he eventually agreed to publish this short note. Almost immediately, a professional astronomer, Fritz Zwicky at the California Institute of Technology, took on the idea. He pointed out that the effect probably would be observable if the two stars were replaced by two galaxies. Today, gravitational lensing is a major topic in galactic astronomy and is used routinely in many other areas of astronomy, especially in the search for exoplanets—planets that orbit stars other than the Sun. The Einstein ring (see fig. 38), often seen in lensing of galaxies, takes its name in deference to Einstein’s calculation in this paper.
1937
159. “On Gravitational Waves” (with Nathan Rosen). Journal of the Franklin Institute 223: 43–54. This paper had a most unusual history, as it was first submitted to the Physical Review under the title “Do Gravitational Waves Exist?” (See also this volume, Part II, Concepts, “Gravitational Waves.”) Angered at receiving a critical referee’s report, Einstein withdrew the paper and sent it instead to the Journal of the Franklin Institute. Realizing that it was indeed flawed, he was eventually forced to alter it. The skepticism expressed in the original draft about the existence of gravitational waves nevertheless influenced the future careers of his assistants, Nathan Rosen and Leopold Infeld. Following his experience with this paper, Einstein never published in the Physical Review again, apart from a short letter.
1938
160. “Our Debt to Zionism.” Address to National Labor Committee for Palestine. New Palestine 28, no. 2 (April 29, 1938): 2–4. Reprinted in Ideas and Opinions (1954). Part of an address given in New York City, April 17, 1938. Focusing on the current troubled times for Jews, Einstein says that Zionism has renewed a sense of community among Jews, enabling many of them to escape the curse of anti-Semitism and engaging them in productive work in Palestine.
161. “Why Do They Hate the Jews?” Trans. Ruth Norden. Collier’s Weekly 102 (November 26, 1938): 9–10, 38. Reprinted in Ideas and Opinions (1954). In answer to this question, Einstein says that Jews were the object of discrimination because they are thinly scattered throughout the Diaspora and therefore unable to defend themselves against attack, usually initiated by envious antagonists. Historically, they have been charged both with trying to assimilate and with being too clannish. He maintains that societies need heterogeneous groups, both political and social, for their invigorating effect on all aspects of life.
162. “Gravitational Equations and the Problems of Motion” (with Leopold Infeld and Banesh Hoffmann), part 1 (see no. 168 for part 2). Annals of Mathematics 39, ser. 2 (1938): 65–100. Using a method based on Gauss’s theorem, the authors tackle the problem of motion of a system of particles in general relativity. Einstein was generally opposed to the use of singularities to describe massive bodies in such physical systems, but here he conceived the notion of concealing the singularity within a surface and performing all integrals only over the surface, thus avoiding the question of the precise details of the mass within. This important paper, known by the initials of the authors’ last names as EIH, was instrumental in furthering progress in the field after Einstein’s death and demonstrated conclusively an old claim of Einstein’s: that the equations of motion in general relativity follow directly from the field equations, without the necessity of a separate statement of the force law.
163. “Generalization of Kaluza’s Theory of Electricity” (with Peter Bergmann). Annals of Mathematics 39, ser. 2 (1938): 683–701. In this paper, Einstein and Bergmann explore the idea that the fifth dimension of the Kaluza-Klein theory is a real physical phenomenon. Instead of ignoring quantities that vary in the direction associated with this dimension, they assume that they exhibit a periodicity (because that dimension is “curled up on itself” or compactified on a scale too small to be seen). The mathematical difficulties this engendered were attacked by Einstein and his assistants later in no. 171.
164. The Evolution of Physics: The Growth of Ideas from Early Concepts to Relativity and Quanta (with Leopold Infeld). New York: Simon & Schuster, 1938. In this popular book, Einstein and Infeld present the ideas behind relativity and trace the development of physics since the time of Galileo. They do so without the use of mathematics, making this a useful guide for laypeople and physicists alike.
1939
165. “Our Goal.” Address at a conference at Princeton Theological Seminary, May 19, 1939. Mimeograph. Reprinted as part 1 of “Science and Religion” in Ideas and Opinions, 41–44. See no. 170 for part 2. See also nos. 126 and 186 on the same topic. According to Einstein, scientific and rational means cannot fully serve to influence a person’s convictions and beliefs—they have their limits. Therefore, the most important function of religion in our social life is to make clear a society’s values and goals—the powerful traditions that have built a foundation for aspirations and values. Traditions do not need to be justified because they have already worked well in a healthy society.
166. “On a Stationary System with Spherical Symmetry Consisting of Many Gravitating Masses.” Annals of Mathematics, ser. 2, 40 (1939): 922–936. In this paper, Einstein attempts to show that what we now call black holes cannot exist in nature. His argument is that a stellar cluster, as it contracted, would accelerate the constituent stars more and more until they were moving at almost the velocity of light. He then concludes that it would be impossible to further compress the system because one would have to add more and more energy in order to compress it more (because of relativistic effects associated with ultrarelativistic particles). Modern studies of gravitational collapse state the reverse: at this extreme concentration, it would be impossible to find the energy to prevent gravitational collapse, and such a condensed cluster of stars would collapse to form a black hole no matter how hard one tried to prevent it.
1940
167. “Freedom and Science.” Trans. James Gutmann. In Freedom: Its Meaning, ed. Ruth N. Anshen, 381–383. New York: Harcourt, Brace. After stating that most people can agree on two goals—to satisfy their basic physical needs through the least amount of work possible, and to be spiritually content, for which they must have the chance to develop their intellectual and artistic gifts—Einstein says that the freedom to express oneself is paramount. People should limit their work time so they will have the time and strength to express themselves creatively or with independent ideas.
168. “Gravitational Equations and the Problems of Motion” (with Leopold Infeld), part 2 (see no. 162 for part 1). Annals of Mathematics 41, ser. 2 (1940): 455–464. In this fol low-up paper, the authors generalize their earlier work so that it is coordinate-independent.
169. “Considerations concerning the Fundamentals of Theoretical Physics.” Address to the 8th American Scientific Congress, Washington, DC, May 24, 1940. Science 91, new ser. (1940): 487–492. Reprinted in Ideas and Opinions (1954) as “The Fundaments of Theoretical Physics.” Einstein traces the development of theoretical scientific thinking and the attempt to find a unifying theoretical basis for each branch of science.
1941
170. “Science and Religion, Part 2.” In Science, Philosophy and Religion, a symposium volume published by the Conference on Science, Philosophy and Religion in Their Democratic Way of Life, New York, 1941. Reprinted as part 2 of “Science and Religion” in Ideas and Opinions (1954), 44–49. See no. 165 for part 1. See also nos. 126 and 186 on the same topic. Einstein says that he can define science, but he cannot define religion. Therefore, if a person claims to be religious, he assumes it is someone who has values of a superpersonal, not materialistic, nature. He says that conflicts between science and religion have sprung from fatal errors, religion can learn from science to achieve its goals, and the source of the need to seek truth through science springs from the religious sphere, that is, from a faith that the rules valid for the world of existence are rational. He makes his famous remark, “Science without religion is lame, religion without science is blind.”
171. “On the Five-Dimensional Representation of Gravitation and Electricity” (with V. Bargmann and P. G. Bergmann). In Theodore von Kármán Anniversary Volume, 212–225. Pasadena: California Institute of Technology, 1941. This paper continues the work begun in no. 163. Einstein and his collaborators attempt to overcome some of the mathematical difficulties encountered in the first paper, but merely uncover serious physical problems, such as that the gravitational field is predicted to be as strong as the electromagnetic field (whereas in reality it is far weaker for interactions between elementary particles). Einstein finally abandoned the Kaluza-Klein theory after this paper, although his idea that there is a periodicity in the hidden (or compactified) dimension did prefigure later characteristics of many versions of string theory.
1942–1943
172. “The Common Language of Science.” Advancement of Science (London): 2, no. 5 (1942). Reprinted in Ideas and Opinions (1954). In this published broadcast recording to a British Association for the Advancement of Science conference in London on September 28, 1941, Einstein speaks of language as an instrument of reasoning and of the intimate connection between language and thinking.
173. “On the Non-Existence of Regular Stationary Solutions of Relativistic Field Equa tions” (with Wolfgang Pauli). Annals of Mathematics 44 (1943): 131–137. Einstein and Pauli, in their only collaboration, show that a singularity-free stationary spacetime that is asymptotically like the Schwarzschild metric of a point mass must have vanishing mass. The same theorem is also proved for the Kaluza-Klein five-dimensional theory.
1944
174. “Remarks on Bertrand Russell’s Theory of Knowledge.” In The Philosophy of Bertrand Russell, ed. Paul A. Schilpp. Library of Living Philosophers, vol. 5. LaSalle, IL: Open Court, 1944. After expressing his admiration for Russell, Einstein discusses the evolution of philosophical thought about the objective world and the world of concepts and ideas.
175. “Gandhi’s Statesmanship.” In Mahatma Gandhi: Essays and Reflections on His Life and Work, ed. S. Radhakrishnan. London: Allen and Unwin, 1944. Einstein expresses his profound admiration for Gandhi and his leadership, famously writing that “generations to come, it may be, will scarce believe that such a one as this ever in flesh and blood walked upon this earth.”
176. “To the Heroes of the Battle of the Warsaw Ghetto.” Bulletin of the Society of Polish Jews (New York) (1944). In this two-paragraph statement, Einstein blames “the Germans as an entire people” for the mass atrocities perpetrated by the Nazi regime in Europe. They were aware of Hitler’s intentions, as outlined in his book and speeches, yet they still voted for him in a landslide election.
177. “Palestine, Setting of Sacred History of the Jewish Race.” Princeton Herald, April 14, 1944. This first of two articles written, together with Einstein’s friend, the literary scholar and Zionist, Erich Kahler, is in response to the views of Philip Hitti, a distinguished professor of Semitic literature at Princeton University. Einstein and Kahler emphasize the moral right of Jews to live under self-rule in the Holy Land. Hitti’s two essays and Einstein/Kahler’s two responses are later republished in Kahler, The Jews among the Nations, pp. 123–149. New York: Frederick Ungar, 1967.
1945
178. “Einstein on the Atomic Bomb.” Ed. Raymond Swing. Atlantic Monthly 176 (November 1945): 43–45. Articles with the same title had appeared in the New York Times on October 27 (p. 17) and October 29 (p. 4). Reprinted as “Atomic War or Peace, Part 1,” in Ideas and Opinions (1954), 118–123. See no. 183 for part 2. (See also this volume, Part III, Organizational Ties, “Emergency Committee of Atomic Scientists,” and Political Philosophy, “World Government.”) Einstein advocates a world government as a way to control the future use of the atom bomb and all armaments. It should be established, he wrote, by the three great military powers: the United States, the Soviet Union, and Great Britain. This world government would have power over all military matters and intercede in countries where oppression occurs, because a world government is preferable to the far greater evil of wars. The Russian Academy of Sciences later denounced Einstein for advocating such a system (see Ideas and Opinions [1954], 134–140).
179. “A Testimonial from Prof. Einstein.” In Jacques Hadamard, An Essay on the Psychology of Invention in the Mathematical Mind, 142–143. Princeton, NJ: Princeton University Press, 1945. Princeton Science Library edition: appendix, in The Mathematician’s Mind: The Psychology of Invention in the Mathematical Field. Princeton, NJ: Princeton University Press, 1996. Einstein replies to a questionnaire sent to mathematicians by Hadamard, a French mathematician, for a survey on how their mental processes work.
1946
180. “Social Obligation of the Scientist.” In Treasury for the Free World, ed. R. Raeburn. New York: Arco, 1946. This book originated from the files of Free World, a publication that disseminated the ideas of international leaders and public officials on the urgent problems of the time. While it was being prepared, the atom bombs fell on Japan. In the book, sixty-one world-famous figures, including Charles de Gaulle, Fiorello La Guardia, Marshal Tito, Julian Huxley, and Einstein, give their opinions on the current world situation. Einstein’s essay is presented in the form of a questionnaire. He is asked (1) how can scientists make their influence felt toward the aim of world cooperation (through the establishment of an international body that presides over military matters); (2) should scientists concern themselves with political matters (every citizen should express his convictions); (3) is there a relationship between the progress of physics and mathematics and the progress of society (yes, because they bring about new technology and because they are efficient counterweights to a materialistic attitude); and (4) what can be done to undo the effects of Nazism (“the Germans can be killed or constrained, but they cannot be re-educated to a democratic way of thinking and acting within a foreseeable period of time”).
181. “E = mc2: The Most Urgent Problem of Our Time.” Science Illustrated 1 (April 1946): 16–17. Reprinted in Ideas and Opinions (1954). Einstein gives an explanation of the world’s most famous equation—the formula for the equivalence of mass and energy—in his own words for the general reader.
1947
182. “The Military Mentality.” American Scholar 16 (1947): 353–354. Reprinted in Ideas and Opinions (1954), 132–134. Einstein accuses America of placing the importance of aggressive power above all other factors that affect relations among nations, resulting in a military mentality in government. He warns that Germany’s similar attitude, beginning with Bismarck and Kaiser Wilhelm II, resulted in Germany’s decline in less than a century. A military mentality is even more dangerous today because weapons are more powerful.
183. “Atomic War or Peace.” As told to Raymond Swing. Atlantic Monthly 180 (November 1947): 29–33. Reprinted as “Atomic War or Peace, Part 2,” in Ideas and Opinions (1954). See no. 178 for part 1. Einstein speaks in favor of outlawing the atom bomb and again advocates a world government for the purpose of averting wars. The Emergency Committee of Atomic Scientists distributed a reprint of this article with a plea for financial support.
184. [Response to the editor on Walter White’s article, “Why I Remain a Negro.”] Saturday Review of Literature 30 (November 1, 1947): 21. Walter White, the secretary of the NAACP, had written an article about his life for the Review in October. In it, he described how he, a blue-eyed and fair-skinned Negro, could have passed for white but chose instead to advocate for civil rights as a black man. Einstein stated: “There is only one road to true human greatness—through suffering.”
1948
185. “A Reply to the Soviet Scientists.” Bulletin of the Atomic Scientists 4, no. 2 (February 1948): 35–37. Writing in December 1947, Einstein responds to the charge made by four prominent Soviet physicists that his call for world government is merely a cover for American hegemonic ambitions. He protests that his only objective in advancing world government is to eliminate a nuclear arms race that would destroy humanity, socialist and capitalist alike. (See also this volume, Part III, Political Philosophy, “World Government.”)
186. “Religion and Science: Irreconcilable?” Christian Register 127 (June 1948): 19–20. Reprinted in Ideas and Opinions (1954). (See also this volume, Part III, Religion.) In this response to a greeting sent by the Liberal Ministers Club of New York City, Einstein states that the answer to the question is complicated because, though people can agree on what science is, they often differ on a definition of religion. The mythical aspect of religion—which is only one aspect of it—is the part that is most likely to cause conflict, and myths are not necessary to pursue religious goals.
187. “On Receiving the One World Award.” An address given at Carnegie Hall, April 27, 1948. Reprinted in Ideas and Opinions (1954). Distraught by the consequences of the recent war and the prospect of continuous rearmament, Einstein again proposes that there is only one path to peace and security: a supranational organization.
188. “Quantum Mechanics and Reality” (Quantenmechanik und Wirklichkeit). Dialectica 2 (1948): 320–324. Einstein restates his belief that the wave function of an individual particle represents only incomplete information about its true physical position and momentum. He believes that ultimately a more complete theory will be found that will incorporate quantum mechanics in the same way, perhaps, that geometrical optics is incorporated into the more complete theory of wave optics.
189. “Atomic Science Reading List.” In ’48: Magazine of the Year (January), 60–61. Maintaining that “it is not enough to know all about isotopes and pitchblende and plutonium” in order to understand atomic energy and its capabilities, Einstein selects and describes six periodicals and books that cover scientific and historical sources as well as the “problems of peace, security, and the continued life of man with man.” These are the Bulletin of the Atomic Scientists, a monthly publication, which he says is the most valuable single source of up-to-date information on atomic energy; Selig Hecht’s Explaining the Atom (1947), an account of the scientific steps that have led to our present knowledge on nuclear fission; John Hersey’s Hiroshima (1946), a novel describing the impact of the atomic bomb on everyday people; Cord Meyer, Jr.’s Peace or Anarchy (1947), a review of the complex problems connected with peace and security; Emery Reves’s The Anatomy of Peace (1945), which discusses the issues of peace and the need for a world government to secure it; and Raymond Swing’s In the Name of Sanity, which contains discussions of the events that followed the news that atomic energy had been discovered.
1949
190. “Why Socialism?” Monthly Review: An Independent Socialist Magazine 1 (May 1949): 9–15. Reprinted in Ideas and Opinions (1954). (See also this volume, Part III, Political Philosophy, “Socialism.”) Though advocating a socialist economy in the interests of social justice, Einstein warned in this essay of the need to protect the rights of the individual in the face of a centralizing, permanent bureaucracy.
191. “Autobiographical Notes” and “Remarks to the Essays Appearing in this Volume.” In Albert Einstein: Philosopher-Scientist, ed. Paul A. Schilpp, pp. 3–94 (in German and English), and pp. 665–688. Library of Living Philosophers, vol. 7. La Salle, IL: Open Court, 1949. Einstein facetiously referred to these Notes, which he wrote in 1946 as a short scientific autobiography, as his “obituary.”
192. “On the Motion of Particles in General Relativity Theory” (with Leopold Infeld). Canadian Journal of Mathematics 3 (1949): 209–214. The authors show that the field equations alone suffice as a basis for solving the problem of motion in general relativity theory, since the Einstein equations not only determine how particles must respond to gravitational forces, but also contain the information necessary to describe those forces. (In contrast, in Newtonian theory the laws of motion and the law of gravitation are given completely separately from each other.)
1950
193. “On the Generalized Theory of Gravitation.” Scientific American 182, no. 4 (April 1950): 13–17. Reprinted in Ideas and Opinions (1954). At the request of the editors of the magazine, Einstein discusses his mathematical investigations into the foundations of field theory in physics.
194. “Introduction.” In Philipp Frank, Relativity: A Richer Truth. London: Jonathan Cape, 1951. In the foreword to this small book on the ethical implications of relativity, Einstein writes that it may seem that logical thinking is not relevant for ethics, but that, indeed, “ethical directives can be made rational and coherent by logical think ing and empirical knowledge.” He states that ethical axioms, like the axioms of science, are established and then tested; if they fit society or an individual, they are accepted.
1951–1952
195. “Introduction.” In Carola Baumgardt, Johannes Kepler: Life and Letters. New York: Philosophical Library, 1951. For this collection of annotated letters from Kepler to his contemporaries, including Galileo, Einstein wrote an introduction tracing how Kepler determined the movement of the Earth in planetary space. Because Earth “itself can be used at any time as a triangulation point, Kepler was also able to determine by observation the true movements of the other planets.” The letters show, he says, that Kepler completed his work under conditions of great personal hardship.
196. “Foreword.” In Dagobert D. Runes, ed., Spinoza: Dictionary. New York: Philosophical Library, 1951. Einstein praises this dictionary of Spinoza’s terminology rendered in Spinoza’s own words as a reliable guide to the philosopher’s works, which are otherwise often difficult to understand.
197. “Foreword.” In Homer Smith, Man and His Gods. Boston: Little, Brown, 1952. In this history of religious and philosophical thought by a prominent biologist, Einstein praises this scientist’s objectivity in presenting his subject. He says such objectivity is rarely found in a “pure historian.”
198. “Those Who Read Only Newspapers See Things Like a Nearsighted Person with No Glasses” (Wer nur Zeitungen liest, sieht die Dinge wie ein Kurzsichtiger ohne Augengläser). Der Jungkaufmann (Zurich) 27, no. 4 (1952): 73. See Ideas and Opinions (1954), 64–65, for an English translation. Einstein states his belief that it is important for young people to read the classics. Because there are only a few exceptional people of letters in any given century, their work is “the most precious possession of mankind.”
199. “On the Moral Obligation of the Scientist.” Trans. Ira Freeman. Bulletin of the Atomic Scientists, February 1952, pp. 34–35. First presented in 1950 as a message to the Italian Society for the Advancement of Science. Einstein examines the question of whether scientists can undertake research as an independent intellectual exercise or if science should lead to practical applications. He fears that, paradoxically, scientists have suffered a tragic fate because they are losing the very freedom and independence they once enjoyed while advancing science and are subordinating themselves to practical objectives. He regards this situation as a moral dilemma that needs to be examined carefully.
200. “Symptoms of Cultural Decay.” Bulletin of Atomic Scientists 8, no. 7 (October 1952). Reprinted in Ideas and Opinions (1954). Einstein writes that politicians should not control the sciences and impede free scientific exchange with other countries. The attitude now is one of such distrust that even in peacetime our lives and work have to be organized as if we are preparing to win a war.
201. “A Comment on a Criticism of Unified Field Theory.” Physical Review 89 (1953): 321. This was Einstein’s final paper on the unified field theory. He was certain about the mathematical concepts but uncertain about the physical aspects.
202. “Letter in Reply to William Frauenglass.” Bulletin of the Atomic Scientists 9 (1953): 230. Reprinted in Ideas and Opinions (1954). In this letter of May 16, 1953, written during the McCarthy witch-hunting era, Einstein advises Brooklyn teacher William Frauenglass to refuse to submit to questioning by the U.S. Senate’s Internal Security Subcommittee. All intellectuals should refuse to testify, not on the basis of the Fifth Amendment but because it is shameful for an innocent citizen to be forced to submit to such an inquisition, which Einstein considers a violation of the spirit of the Constitution.
1954
203. Ideas and Opinions. Trans. Sonja Bargmann. New York: Crown, 1954. The most popular anthology of Einstein’s writings in English, still in print, though some of the presentations are not faithful to the published originals.
204. “Algebraic Properties of the Field in the Relativistic Theory of the Asymmetric Field” (with Bruria Kaufman). Annals of Mathematics 59 (1954): 230–244. See also no. 206. This was Einstein’s first paper with a female collaborator, his assistant at the time. In the paper, they seek to modify the field equations of general relativity in order to permit asymmetries in the field. In particular, the affine connection is asymmetric, often described as a torsion tensor. Einstein hoped that this approach would lead to a natural expression of the intrinsic spin of fundamental particles. Thus, as with so much of his work on relativity in his later years, this theory is ultimately part of his broader unified field theory program.
205. The Meaning of Relativity. 5th ed. Princeton, NJ: Princeton University Press, 1954. This book is the final edition of Einstein’s seminal work. In it, he completely revises appendix 2, “Generalization of Gravitation Theory,” of the fourth edition, renaming it “Relativistic Theory of the Non-Symmetric Field”—his final attempt to extend or generalize his theory to achieve a unified theory of at least the gravitational and electromagnetic fields.
1955
206. “A New Form of the General Relativistic Field Equations” (with Bruria Kaufman). Annals of Mathematics 62 (1955): 128–138. See also no. 204. This was Einstein’s final scientific publication and gave the final form of the field equations for general relativity, based on the asymmetric affine connection approach on which he had been working for the last several years of his life. In spite of Einstein’s hopes for it, the theory did not have any influence within the field of general relativity, nor with the rest of physics. A final report on the progress of his work was presented within months of his death by his collaborator Bruria Kaufman at the 1955 Bern conference to commemorate the fiftieth anniversary of relativity theory. This conference brought together many people who were interested in general relativity and was influential in sparking a resurgence of interest in the subject, which led to its ultimately becoming a major field of physics. Today it is sometimes referred to as GR0, the prequel to a series of conferences devoted to GR (general relativity).
207. “The Russell-Einstein Manifesto.” Issued from London, July 9, 1955, and published worldwide. See this volume, Part III, Political Contexts, “Postwar and Cold War,” for the complete statement, or see www.nuclearfiles.org.
208. “Remembrances” (Erinnerungen-Souvenirs). Schweizerische Hochschulzeitung 28 (special volume), pp. 145–153. In this remembrance of his Swiss school days, Einstein recalls, among other things, that he studied the work and lives of the “masters of theoretical physics” while he was a student.
209. “Albert Schweitzer at Eighty.” Privately printed by Homer A. Jack, in To Albert Schweitzer: A Festschrift Commemorating His Eightieth Birthday; reprinted in Christian Century 72, no. 2 (1955). Einstein shows appreciation for the aging theologian, organist, philosopher, and physician, best known for his medical mission in Lambaréné, present-day Gabon in West Africa. He admires his robust health and his “ideally fused” kindliness and yearning for beauty.