James Clerk Maxwell

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James Clerk Maxwell Signature of James Clerk Maxwell

James Clerk Maxwell (born June 13, 1831 in Edinburgh , †  November 5, 1879 in Cambridge ) was a Scottish physicist . He developed a set of equations (the Maxwell equations ), which are the fundamentals of electrodynamics , in particular in 1864 he predicted the existence of electromagnetic waves , which Heinrich Hertz was the first to generate and prove in 1886.

His field theory, named after him, is one of the most important achievements in physics and mathematics of the 19th century.

In 1866 he developed the kinetic gas theory and is thus considered one of the founders of statistical mechanics alongside Ludwig Boltzmann, who later worked . The classic velocity distribution of gas molecules ( Maxwell-Boltzmann distribution ) is named after both. He published the first color photograph in 1861 as evidence of the additive color mixing theory .

Maxwell was the last representative of the younger line of the famous Scottish family Clerk of Penicuik . In 1858 he married Katherine Mary Dewar, daughter of the principal of Marischal College in Aberdeen . The marriage remained childless. Maxwell died of stomach cancer in Cambridge at the age of 48 .

meaning

James Clerk Maxwell's birthplace at 14 India Street, Edinburgh

Maxwell is generally considered to be the 19th century naturalist with the greatest influence on 20th century physics . He made contributions to fundamental models of nature and was considered to be a bridge between mathematics and physics. Just a few years after his death, James Clerk Maxwell's importance for the natural sciences was accepted worldwide, without the appreciation at that time - as was often the case later - limited primarily to his research into electromagnetism . In 1931, on the centenary of Maxwell's birth, Albert Einstein described his work as "the deepest and most fertile that physics has discovered since Newton ".

Combining algebra with elements of geometry is one of the main features of his work. Maxwell showed that electrical and magnetic forces are two complementary phenomena of electromagnetism. He showed that electric and magnetic fields in the form of electromagnetic waves  can move through space at a constant speed of around 3 · 10 8 m / s, which corresponds exactly to the speed of light . He postulated that light was a form of electromagnetic radiation.

Maxwell has summarized the results of previous electromagnetic and optical experiments and observations in a series of mathematical equations. These equations (as well as the Maxwell distribution) have since proven extremely useful in physics. They have proven themselves in all cases and have produced some new laws of electromagnetism and optics, the most important ones relating to electromagnetic radiation. The equations are fundamental to radio and television and can be used to study x-rays, gamma rays, infrared rays and other forms of radiation.

Life

Early years

Maxwell in Cambridge in 1855, the colored disc of his first optical experiments in hand.

Maxwell was born the only child of John Clerk Maxwell, a lawyer from Edinburgh, at 14 India Street in the Scottish capital, Edinburgh . Maxwell's early upbringing, which included Bible study , came from his Christian mother. He spent most of his early youth at the Glenlair family estate near Dumfries . Maxwell's mother died when he was only eight years old. Maxwell later went to the Edinburgh Academy. His school nickname was "Dafty" (fool or nerd). He got it because he wore homemade shoes on the first day of school. In 1845, at the age of 14, Maxwell wrote a paper describing the way to draw mathematical curves with a string.

Middle years

In 1847 Maxwell enrolled at the University of Edinburgh and studied natural philosophy, moral philosophy and mental philosophy. In Edinburgh he studied with Sir William Hamilton . At the age of 18, still a student in Edinburgh, he wrote two papers for the Transactions of the Royal Society of Edinburgh , one of which, On the Equilibrium of Elastic Solids , formed the basis for a unique discovery in later in life, the temporary birefringence in viscous liquids caused by shear forces .

In 1850 Maxwell moved to Cambridge University . First he enrolled at Peterhouse , but then went to Trinity College because he believed it would be easier to get a scholarship here. At Trinity College, he was elected to a secret association known as the Cambridge Apostles . In November 1851, Maxwell studied with his tutor William Hopkins , whose nickname was "wrangler-maker" (" Wranglers " are students who pass the math test best). Maxwell completed much of the elaboration of his electromagnetic equations while he was still an undergraduate student.

In 1854, Maxwell graduated with the second-best math exam of his year. Immediately after graduating, he published a scientific paper On Faraday's Lines of Force ( About Faraday lines of force ), in which he gave a first indication of his electrical researches which should culminate in the most important work of his life.

First permanent color photography, demonstrated by James Clerk Maxwell in a lecture in 1861

From 1855 to 1872 he periodically published a series of valuable research relating to color vision and color blindness . The instruments he used for this research were simple and useful (e.g. color spinning top). "For his research on the composition of colors and other contributions to optics" he was awarded the Rumford Medal by the Royal Society in 1860 .

In 1861 he published the first color photograph as evidence of the theory of additive color mixing .

In 1856 Maxwell was appointed to the chair of natural philosophy at Marischal College in Aberdeen, which he held until the merger with King's College in 1860.

In 1856 he won the Adams Prize in Cambridge for an original essay with which he proved that the rings of Saturn are neither liquid nor compact solids, but that stability can only exist if they consist of a multitude of small solid bodies that are not connected together. He also mathematically refuted the nebula theory, which states that galaxies are formed by the progressive condensation of gaseous nebulae. According to his theory, proportions of small solids are necessary for this.

In 1860 Maxwell became a professor at King's College London .

In 1861 he was elected as a member (" Fellow ") in the Royal Society. During this time he worked on elastic bodies and pure geometry.

Kinetic gas theory

One of Maxwell's most important researches dealt with the kinetic theory of gases . Starting with Daniel Bernoulli , this theory was further elaborated through the following investigations by John Herapath , John James Waterston, James Prescott Joule, and especially Rudolf Clausius . It reached such a level of perfection that its predictive accuracy made it beyond doubt. Maxwell, who showed himself to be a brilliant experimenter and theorist in this field, developed it in a superior manner.

In 1865 Maxwell moved to Glenlair, Kirkcudbrightshire , on the estate he had inherited from his father, John Clerk Maxwell.

In 1868 he gave up the chair of physics and astronomy at King's College in London.

In 1860 he formulated the kinetic gas theory that was later generalized by Ludwig Boltzmann . His formula, called the Maxwell distribution , calculates the proportion of gas molecules that move at a certain speed at a given temperature . In kinetic gas theory, temperature and pressure cause the molecules to move. This approach to the subject of research generalized the previous laws of thermodynamics and explained the observations and experiments in more detail. Maxwell's work on thermodynamics led him to a thought experiment known as the " Maxwellian Demon ".

Electromagnetism

A postcard from Maxwell to Peter Guthrie Tait .

When Maxwell became interested in electricity, he wrote to William Thomson, 1st Baron Kelvin , and asked him how best to proceed. Kelvin recommended that Maxwell read the published works of Faraday, Kelvin, Ampère, and then those of the German physicists, in the order given.

Most of Maxwell's life's work was devoted to research into electricity . Maxwell's most important contribution was the elaboration and mathematical formulation of previous research on electricity and magnetism by Michael Faraday , André-Marie Ampère and others in a system of interrelated differential equations . With this he underpinned the hypothesis of the identity of electricity and magnetism, which had been widespread since the beginning of the 19th century, with a plausible mathematical model. In the beginning there were 20 equations, which were later summarized using the vector notation. These equations, now collectively referred to as Maxwell's equations (or sometimes "Maxwell's wonderful equations"), were first published in the Royal Society in 1864. Together they describe the behavior of both electric and magnetic fields, as well as their interaction with matter. In addition, Maxwell predicted waves of vibrating electric and magnetic fields moving through empty space. He could predict the speed from simple electrical experiments; Using the data available at the time, he calculated the velocity of propagation to be 310,740,000 m / s. Maxwell wrote in 1864:

"This velocity is so nearly that of light, that it seems we have strong reason to conclude that light itself (including radiant heat, and other radiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws. "

“ This speed is so close to that of light that we have strong reason to conclude that light itself (including thermal radiation and possible other radiation) is an electromagnetic disturbance that, according to electromagnetic laws, is in the form of waves in the electromagnetic Field propagates. "

Maxwell's assumption was essentially correct. The wave theory was later confirmed by experiments by Heinrich Hertz and forms the basis of all radio technology . The quantitative connection between light and electromagnetism is viewed as a great triumph of 19th century physics. At that time Maxwell believed that the propagation of light required a medium in which the waves could propagate. About this medium, which was called light ether , Maxwell wrote an entry in the Encyclopædia Britannica in 1878 with the following summary at the end:

“Whatever difficulties we have in developing a conclusive idea of ​​the nature of the ether, there can be no doubt that the interplanetary and interstellar spaces are not empty, but are filled with a material substance or a body that is filled with Security is the largest and probably the most uniform body we know of. "

In the course of time, however, more and more difficulties arose with the existence of such a medium, which filled the whole room but could not be found by mechanical means, with the results of experiments such as e.g. B. the Michelson-Morley experiment in harmony. In addition, it seemed to need an absolute frame of reference in which the equations were valid. This would have meant that the equations would have had a different form for a moving observer. This difficulty stimulated Einstein to formulate the special theory of relativity and in this process denied the need for a light ether.

Structural analysis

Less well-known, but groundbreaking at the individual scientific level, are Maxwell's contributions to truss theory and graphic statics. Erhard Scholz rated the duality relation of truss theory and force polygon found by Maxwell in 1864 and 1867 as the "parade horse of graphic statics." In elementary geometry, Maxwell's theorem names a statement about triangles after him, which he proved in the context of his work on statics.

Late years

James and Katherine Maxwell, 1869.

In 1871 he was appointed the first Cavendish Professor of Physics to Cambridge. Maxwell oversaw the construction of the Cavendish Laboratory . He oversaw every step of the construction of the building and the purchase of the precious collection of equipment the laboratory was stocked with thanks to its generous founder, the 7th Duke of Devonshire. He wrote a textbook on the theory of heat (1871) and an excellent introductory treatise on body and movement (1876). In 1874 he was elected to the American Academy of Arts and Sciences . One of Maxwell's last great contributions to science was the analysis of Henry Cavendish's research . It turned out that Cavendish had dealt with questions about the mean density of the earth and the composition of the water. When Maxwell died in 1879 at the age of 48, John William Strutt, 3rd Baron Rayleigh , succeeded him as Cavendish Professor. This introduced systematic courses in physics.

The Life of James Clerk Maxwell was published in 1882 by his classmate and lifelong friend, Professor Lewis Campbell (1830-1908). His collected works, including the series of articles on the properties of matter, were published in two volumes by Cambridge University Press in 1890.

Honors

In Maxwell's honor, the cgs unit Maxwell of the magnetic flux was named. A mountain range on Venus, Maxwell Montes, was named after him because it was discovered by the electromagnetic waves (radar observations) he postulated. In addition, the James Clerk Maxwell Telescope on Mauna Kea , the largest telescope in the world for electromagnetic radiation between infrared and microwaves with a diameter of 15 m, bears his name. A moon crater and the asteroid (12760) Maxwell are named after James C. Maxwell.

The James Clerk Maxwell Prize for Plasma Physics and the Maxwell Medal are named in his honor.

Publications (selection)

literature

Web links

Commons : James Clerk Maxwell  - Album with pictures, videos and audio files
Wikisource: James Clerk Maxwell  - Sources and full texts (English)
Wikiquote: James Clerk Maxwell  - Quotes

Individual evidence

  1. ↑ The Brockhaus Konversationslexikon describes Maxwell around 1896 as follows: “The main achievements of Ms are in the field of mechan. Heat theory, the expansion of dynamic gas theory; in the field of electricity theory, however, M. is the founder of electro-optics, which Hertz further developed. In his studies of magnetism and electricity M. followed up with Faraday and supplemented his work after the mathem. Direction. As early as 1856 he worked on Faraday's lines of force , then in 1864 he published his dynamic theory of the magnetic field and in 1868 the method of direct comparison of the electrostatic with the electromagnetic force . "Quoted from Brockhaus' Konversationslexikon, FA Brockhaus Leipzig, Berlin and Vienna, 14th edition, 1894-1896
  2. ^ For the authors' collective von Meyers Konversationslexikon around 1892 Maxwell was “next to Thomson the most important mathematical physicist in England. His numerous and significant works mainly cover the mechanical theory of heat, especially the more recent gas theory, to the development of which he has contributed significantly, and the theory of electricity, the theoretical treatment of which he has taken entirely new paths. ”Quoted from Meyers Konversationslexikon, Verlag des Bibliographical Institute, Leipzig and Vienna, 4th edition, 1885–1892
  3. ^ On the Description of Oval Curves, and those having a plurality of Foci. By Mr. Clerk Maxwell Junior, with remarks by Professor Forbes. Communicated by Professor Forbes. Monday April 6th, 1846 - Proceeding of the Royal Society of Edinburgh
  4. ^ The University of Aberdeen
  5. ↑ James Clerk Maxwell: On the stability of the motions of Saturn's rings. Cambridge 1859 online .
  6. ↑ The Maxwell at Glenlair Trust
  7. ^ Yelin, Julius von, "Magnetism and Electricity as Identical Primordial Forces", Munich Lentner, 1818
  8. ^ Maxwell, James Clerk: A Dynamical Theory of the Electromagnetic Field . Submitted in 1864 and then published in: Philosophical Transactions of the Royal Society of London (155), 1865, pp. 459-512
  9. ^ Complete original text of Maxwell's entry on the ether in the Encyclopædia Britannica, Ninth Edition on Wikisource
  10. ↑ Quoted and presented in a historical context in: Leonard Mlodinow : Das Fenster zum Universum. A little history of geometry (Original: Euclid's Window ), Campus Verlag 2002, ISBN 3-593-36931-1 - Part 4, The story of Einstein , pages 171-177.
  11. ^ Karl-Eugen Kurrer : Contributions to the theory of statically indeterminate frameworks . In: History of structural engineering. In search of balance . 2nd, greatly expanded edition. Ernst & Sohn , Berlin 2016, ISBN 978-3-433-03134-6 , pp. 481-486 .
  12. ↑ Karl-Eugen Kurrer: From graphic statics to graphostatics . In: History of structural engineering. In search of balance . 2nd, greatly expanded edition. Ernst & Sohn, Berlin 2016, ISBN 978-3-433-03134-6 , pp. 455-470 .
  13. ↑ Erhard Scholz: Symmetry. Group. Duality. On the relationship between theoretical mathematics and applications in crystallography and structural engineering in the 19th century . In: Erwin Hiebert and Hans Wußing (eds.): Science Networks - Historical Studies . tape 1 . Birkhäuser Verlag, Basel 1989, ISBN 3-7643-1974-7 , p. 201 .
  14. ^ Venus - Maxwell Montes and Cleopatra Crater. nasa.gov, accessed March 2, 2018 .
personal data
SURNAME Maxwell, James Clerk
BRIEF DESCRIPTION Scottish physicist
DATE OF BIRTH June 13, 1831
PLACE OF BIRTH Edinburgh
DATE OF DEATH November 5, 1879
Place of death Cambridge