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Book of the Month

Einstein's miracle year: the Annalen der Physik papers of 1905 - March 2005

Annalen der Physik, 17-18, 1905. [Rare Journals Collection]

by Hugh Cahill, Senior Information Assistant, Foyle Special Collections Library

Book of the month archive

Picture of Albert Einstein taken from the collected papers he presented to King's College in 1921. Albert Einstein. Einstein collected papers, 1921 [Early Science Collection QC3 EIN]

This year is the 100th anniversary of five important academic papers written by Albert Einstein (1879-1955), in which he provided fundamental insights into the physical world, changing, amongst other things, the way we think about the nature of light and the nature of space and time. The volume, quality and importance of Einstein's work in 1905 has led to that year being called his annus mirabilis, or miracle year.

In 1905 Einstein was living in Bern with his wife, Mileva, and their young son, Hans Albert and working in the Swiss patent office as a technical expert third class. He had graduated in 1900 from the Eidgenössische Technische Hochschule (the ETH) as a teacher of physics and mathematics and had taken a number of temporary teaching jobs before eventually joining the patent office in 1902 - a position which was initially temporary but which was made permanent in 1904. During these early years at the patent office Einstein was very active scientifically, publishing several papers on thermodynamics in Annalen der Physik and reading a paper entitled Theory of electromagnetic waves in front of the Bern Association of Scientists in December 1903. However, 1905 was to be his most productive year yet, as not only did complete his doctoral thesis but he also numerous reviews of scientific papers and four major papers published in the prestigious scientific journal Annalen der Physik.

In March, just after his twenty-sixth birthday, Einstein sent Annalen der Physik a paper entitled, Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt (known in English as On a heuristic point of view concerning the production and transformation of light), which was published on 9 June . The ideas contained in this paper revolutionised the theory of light. Indeed it is the only paper of all the 1905 papers which Einstein himself described as revolutionary. It explained among other things, the photoelectric effect. This is the phenomenon whereby if a light is shined upon certain metals (such as potassium) a stream of particles (electrons) is released. The wave theory of light predicted that both the energy and the number of the electrons emitted from the metal should increase with an increase in the intensity of light; however, this proved not to be the case. Experiments showed that only the number, and not the energy, of the electrons increased with the increase of the intensity of the light. Using Max Planck's quantum hypothesis Einstein proposed the idea that light is composed of individual quanta (particles), and that light, as well as exhibiting wavelike behaviour, also demonstrates certain properties peculiar to particles. These quanta became known later as photons. If light was composed of these quanta the observations of the photoelectric effect could be explained in the following manner - individual quanta (photons) of light penetrate the metal and knock electrons loose from atoms. By increasing the intensity of the light the number of quanta is increased. However if the frequency of the light remains the same the energy of each individual photon remains the same. Thus, while the number of electrons emitted increases (with increasing light intensity) the energy transmitted to them by the particles of light remains the same.

Opening of : "Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?" in Annalen der Physik, 1905 [Rare Journals Collection]. In this paper Einstein introduced the relationship between mass and energy that came to be represented by the equation E=mc².

The next month Einstein submitted his doctoral thesis, entitled Eine neue Bestimmung der Moleküldimensionen (A new determination of molecular dimensions) to the University of Zurich. When Einstein had initially submitted this work, it had been rejected on the grounds that it was too short. Einstein added a single sentence and resubmitted it. This time it was accepted; to the great amusement of Einstein. It shows how to use fluid phenomena to determine Avogadro's Number (the number of molecules in a mole of a substance) and, although not as revolutionary as the other papers he produced that year, its numerous practical applications ensured that it became one of Einstein's most frequently cited papers. Furthermore, at a time when the existence of atoms and molecules was still being debated and when a number of eminent physicists, such as Georg Helm and Ernst Mach, were sceptical about their existence, it provided evidence (although indirectly) to help bolster atomic theory. Einstein's doctoral thesis was approved on 27 July 1905 and the degree was formally awarded 15 January 1906. Shortly after it was approved, Einstein sent it, with slight revisions, to Annalen der Physik, which published it early in 1906.

Further evidence for the actual existence of molecules was provided by Einstein's paper on Brownian motion (the random motion of microscopic particles suspended in a liquid or gas observed and described in 1827 by Scottish botanist Robert Brown). The paper was entitled Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen (On the movement of small particles suspended in stationary liquids required by the molecular-kinetic theory of heat) and set out a theoretical explanation for Brownian motion. Sent by Einstein to Annalen der Physik in May, it was published in July. In the introduction to this paper Einstein reported that the kinetic theory of heat predicts that small particles suspended in water should execute a random motion visible under the microscope and that he suspected this motion was Brownian motion but that there was insufficient experimental data to be sure. Einstein was saying that the random movements of particles suspended in a liquid were caused by collisions between the invisible molecules of the liquid and the larger particles. He went on to say that if this prediction proved correct "then classical thermodynamics can no longer be viewed as strictly valid even for microscopically distinguishable spaces, and an exact determination of the real size of atoms becomes possible." However, if proved wrong it would be a powerful argument against the kinetic theory of heat. Einstein concluded his paper with the hope that "a researcher will soon succeed in solving the problem posed here, which is of such importance to the theory of heat". The experimental work carried out by the French physicist Jean Perrin and others showed that the equations which Einstein set out in this paper were accurate and did much to promote the general acceptance of the reality of atoms and the kinetic theory of heat.

In the 26 September issue of Annalen der Physik Einstein's special relativity theory paper, Zur Elektrodynamik bewegter Körper (On the electrodynamics of moving bodies) was published. Einstein postulated that for all frames of reference the speed of light in a vacuum is a constant and that the laws of physics are the same in all inertial (non-accelerating) frames of reference and therefore that time and motion are relative to the observer. Some of the consequences of these ideas are very counterintuitive. For example, a person on Earth looking at a spaceship in the sky above will observe that the length of the spaceship contracts in the direction of travel the closer it approaches the speed of light. Furthermore, if the same observer on Earth could see the astronauts inside the spaceship he would observe that they would seem to slow down more and more the closer the spaceship approached the speed of light. An hour on the spaceship is longer than an hour on Earth - time is dilated. Although it is counterintuitive, there is experimental evidence for time dilation. In the 1970s experiments were carried out with atomic clocks aboard jetliners on round the world flights. On their return these clocks were compared to clocks in the laboratory and were found to be slightly behind them even though the planes had flown much more slowly than the speed of light - time aboard the planes was dilated. In November, Annalen der Physik published a follow up paper entitled Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig? (Does the inertia of a body depend upon its energy content?). This footnote to the special theory of relativity established the equivalence of mass and energy - the energy of a quantity of matter E, with mass m, is equal to the product of the mass and the square of the speed of light and, although Einstein did not express it in that way in his 1905 paper, this relationship later came to be represented by perhaps the most iconic equation of all time, E=mc².

Portrait of James Clerk Maxwell, one of Einstein's heroes, taken from: Nature. October, 1881. [Rare Journals Collection ]

Despite the remarkable achievements of 1905, Einstein was to remain at the patent office for several more years. Eventually in 1908, got the academic post he had long wanted being appointed a lecturer at the University of Bern after having his Habilitation thesis (a qualification needed to teach in a university) Consequences for the constitution of radiation following from the energy distribution law of black bodies accepted. However, it was not until the following year that Einstein resigned from the patent office to take up a professorship in physics at the University of Zurich. In 1911 he moved on to the Karl-Ferdinand University in Prague where he was to stay until his return to Germany in 1914 to take up a research position in the Prussian Academy of Sciences. In the years 1915-1916 Einstein completed and outlined his general theory of relativity, in which he postulated that gravity is not a force, but a curved field in the space-time continuum, created by the presence of mass. Einstein predicted that a ray of light from a distant star, passing near the Sun, would appear to be bent slightly in the direction of the Sun and if this could be observed (a total eclipse would be the only time it could be observed) it would provide experimental evidence in favour of his theory. In 1919 an expedition run by the Royal Society photographed the solar eclipse on 29 May of that year and made calculations that vindicated Einstein's predictions. Einstein was acclaimed in the press and by his fellow scientists and became an international celebrity.

In 1921 Einstein received the Nobel Prize, not for his work on relativity but for his 1905 work on the photoelectric effect. In June of that year Einstein visited England. After lecturing at Manchester University he moved on to London, where, on 13 June, he visited Westminster Abbey to put a wreath on the tomb of his hero Sir Isaac Newton. That evening he delivered a lecture at King's College London, where another of Einstein' s heroes James Clerk Maxwell had done his important work on electrodynamics. The lecture was entitled The Development and Present Position of the Theory of Relativity. Einstein spoke for over an hour without notes and when he finished he received a standing ovation.

To commemorate his visit to King's, Einstein gave copies of several of his papers to the library. They are still held in the Foyle Special Collections Library, which also houses the early volumes of Annalen der Physik, including the 1905 issues.

Further reading

Denis Brian. Einstein: a life. New York ; Chichester : Wiley, 1996. [Maughan Library QC16. E5 BRI]

John Stachel (ed.) Einstein's miraculous year : five papers that changed the face of physics. Princeton, N.J. : Princeton University Press, c1998. [Maughan Library QC16.E5 EIN]

J.B. Kennedy. Space, time and Einstein: an introduction. Chesham: Acumen, 2003.[ Maughan Library QC173.57 KEN]

The collected papers of Albert Einstein. Vol. 7, The Berlin years : writings, 1918-1921. Translated by Alfred Engel. Princeton, N.J. ; Oxford : Princeton University Press, [2002]. [Maughan Library QC3 EIN]

The collected papers of Albert Einstein. Vol. 2, The Swiss years : writings, 1900-1909. Translated by Anna Beck, Princeton, N.J. : Princeton University Press, 1989. [Maughan Library QC3 EIN]

Websites

Einstein-Image and impact. Availabe at: http://www.aip.org/history/einstein/index.html

Also of interest

Albert Einstein. "Die Relativitätstheorie" off-print from Physik, Teil 3, Abt. 3,1. Leipzig ; Berlin : Druck und Verlag von B. G. Teubner, 1915. [Early Science Collection QC3 EIN]

Albert Einstein. "Spielen Gravitationsfelder im Aufbau der materiellen Elementarteilchen eine wesentliche Rolle?" off-print from Sitzungsberichte der preussischen akademie der wissenschaften, 1919. XX . [Berlin?] : [Akademie der Wissenschaften?], 1919. [Early Science Collection QC3 EIN]

Albert Einstein. "Theoretische Atomistik" off-print from Physik, Teil 3, Abt. 4,1. Leipzig ; Berlin : Druck und Verlag von B. G. Teubner, 1915. [Early Science Collection QC3 EIN] / von Albert Einstein.

Albert Einstein. "Zur Quantentheorie der Strahlung" off-print from Mitteilungen der Physikalischen Gesellschaft Zürich, Nr. 18, 1916. [Zürich] : [s.n.], 1916. [Early Science Collection QC3 EIN]

Isaac Newton. Philosophiæ naturalis principia mathematica. Londini : Jussu Societatis Regiæ ac typis Josephi Streater, 1687. [Rare Books CollectionQA803.A2 ]

James Clerk Maxwell. The scientific papers of James Clerk Maxwell. Cambridge : At the University Press, 1890. [Early Science Collection FOL. QC3 MAX]

James Clerk Maxwell. On a method of making a direct comparison of electrostatic with electromagnetic force : with a note on the electromagnetic theory of light. [S.l. : s. n., 1868?]. [Wheatstone Collection PAMPH.BOX QC760. MAX ]

James Clerk Maxwell. A dynamical theory of the electromagnetic field. [S.l. : s.n., 1864?]. [Wheatstone Collection PAMPH.BOX QC665.E4 MAX]

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