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 ( Maxwell's equations), which form the foundations of the theory of electricity and magnetism. He also discovered the velocity distribution of gas molecules ( Maxwell distribution ). He published in 1861 the first color photograph as evidence for the theory of additive color mixing.

Maxwell was the last representative of the younger branch of the famous Scottish family Clerk of Penicuik. At 27, he married Katherine Mary Dewar. The marriage remained childless. Maxwell died at the age of 48 in Cambridge from stomach cancer.

Importance

Maxwell is generally regarded as the natural scientists of the 19th century with the greatest impact on the physics of the 20th century. He provided input to basic natural models and was regarded as a bridge between mathematics and physics. Just a few years after his death, James Clerk Maxwell was accepted meaning for the natural sciences world without you then, in the assessment - how often later - limited mainly to his exploration of electromagnetism. In 1931, the centennial of Maxwell's birth, Albert Einstein described his work as " the most profound and most fruitful that physics has discovered since Newton".

To combine algebra with elements of geometry, is a fundamental characteristic of his work. Maxwell showed that electric and magnetic forces are two complementary phenomena of electromagnetism. He showed that electric and magnetic fields in the form of electromagnetic waves with a constant speed of about 3108 m / s can move through the space, which corresponds exactly to the speed of light. He postulated that the light is a form of electromagnetic radiation.

Life

Early years

Maxwell was born as the only child of lawyer John Clerk Maxwell of Edinburgh in the India Street 14 in the Scottish capital Edinburgh. Maxwell's early education, which also included the study of the Bible, he was granted by his Christian mother. His early youth was spent mostly at the family seat Glenlair at Dumfries. Maxwell's mother died when he was only 8 years old. Later, Maxwell went to the Edinburgh Academy. His nickname at school was " Dafty " ( Dussel or nerd ). He got it because he wore homemade shoes on the first day of school. 1845, at the age of 14 years, Maxwell wrote a paper that describes the way to draw mathematical curves with a piece of string.

Mean annual

1847 Maxwell enrolled at the University of Edinburgh and studied natural philosophy, moral philosophy and mental philosophy. In Edinburgh, he studied under Sir William Hamilton. 18 years old, still a student in Edinburgh, he wrote two posts for the Transactions of the Royal Society of Edinburgh, one of which, On the Equilibrium of Elastic Solids ( About the equilibrium of elastic solids ), the basis for a unique discovery in laid his later life, the temporary birefringence in viscous liquids by shear forces.

In 1850, Maxwell to the University of Cambridge. First, he enrolled at Peterhouse, but then went to Trinity College, because he believed easier to get a scholarship here. At Trinity College he was in a secret society known as the Cambridge Apostles chosen. In November 1851 Maxwell studied under his tutor William Hopkins, whose nickname is " wrangler maker" was ( " Wrangler " are students, the best pass the math test). A large part of the elaborations of his electromagnetic equations completed Maxwell when he was still a student without a degree.

1854 Maxwell concluded his studies with the second best math test in his class. Immediately after his graduation he published a scientific paper On Faraday 's Lines of Force ( About Faraday's 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.

From 1855 to 1872 he published at intervals a series of valuable researches in connection with the color vision and color blindness, for which he was in 1860 awarded the Rumford Medal of the Royal Society. The instruments he used for this research were easy and convenient (eg color circle).

1856 Maxwell was appointed to the chair of natural philosophy at Marischal College in Aberdeen, a position he held until the merger of the two colleges in 1860.

In 1859, he won the Adams Prize at Cambridge for an original essay entitled "On the Stability of Saturn 's Rings " ( On the stability of Saturn's rings), in which he came to the conclusion that the rings could not be entirely solid or liquid be. Maxwell showed that stability could only prevail if the rings of numerous small solid bodies exist. He also refuted mathematically the nebular theory which states that galaxies formed through the progressive condensation of gaseous nebulae. According to his theory shares of small solids are necessary. In 1860, Maxwell Professor at King's College in London. In 1861 he was elected as a member ( "Fellow" ) to the Royal Society. He worked in this period by elastic body and pure geometry.

Kinetic theory of gases

One of Maxwell's most important research dealt with the kinetic theory of gases. Beginning with Daniel Bernoulli, this theory was further elaborated by the following investigations by John Herapath, John James Waterston, James Prescott Joule, and particularly by Rudolf Clausius. It reached such perfection that their prediction accuracy made ​​them beyond doubt. Maxwell, who showed up in this area as a brilliant experimentalist and theorist, she continued to develop superior.

In 1865, Maxwell moved his residence to Glenlair in Kirkcudbrightshire, on the estate that 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 later generalized by Ludwig Boltzmann kinetic theory of gases. Its formula called Maxwellian distribution, calculates the amount of gas molecules moving at a given temperature at a given speed. The kinetic theory of gases the temperature and pressure cause the movement of the molecules. This approach to the research objectives, the preceding generalized laws of thermodynamics and explained the observations and experiments in more detail. Maxwell's work on thermodynamics led him to a thought experiment which was known under the name " maxwell demon shear ".

Electromagnetism

The largest part of Maxwell's life's work was devoted to the study of electricity. Maxwell's most important contribution was the development and mathematical formulation of previous research on electricity and magnetism by Michael Faraday, André- Marie Ampère, and others linked together in a system differential equations. This he underscored the beginning of the 19th century, widespread hypothesis of the identity of electricity and magnetism by a plausible mathematical model. Initially, there were 20 equations, which were then collected by the vector notation. These equations, which today as Maxwell equations ( or sometimes referred to as " wonderful Maxwell's Equations " ) are referred to, were first published in 1864 in the Royal Society. Together they describe the behavior of both the electric and magnetic fields, as well as its interaction with matter. In addition, Maxwell predicted waves of oscillating electric and magnetic fields that move through empty space. The speed he could predict from simple electrical experiments; by he used the data that were available at that time, he calculated the propagation velocity to 310 740 000 m / s Maxwell wrote in 1864:

"This velocity is so nearly did of light, did it Seems we have strong reason to Conclude that slight Itself (including radiant heat, and other radiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field accor ding to electromagnetic laws. "

" This velocity is so close to the speed of light, that we have a strong reason to believe that the light itself (including radiant heat and other radiation, if it exists ), an electromagnetic wave. "

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

" What are the difficulties we have to develop a consistent picture of the nature of the ether: There can be no doubt that the interplanetary and interstellar space is not empty, but that both are filled with a material substance, which certainly the most extensive and probably most uniform matter, of which we know. "

Over time, however, more and more difficulty, the existence of such a medium that filled the whole room, but by mechanical means could not be found to bring the results of the experiments such as the Michelson - Morley experiment showed consistent. In addition, there appeared an absolute reference system, in which the equations were valid to need. This would have the consequence that the equations for a moving observer would have had a different shape. This difficulty suggested to Einstein to formulate the theory of special relativity and in the process denied Einstein the need for a luminiferous ether.

Later years

" For his researches on the composition of the colors and other contributions to optics ", he was awarded by the Royal Society in 1860 with the Rumford Medal; a year later he was elected as a member ( "Fellow" ) to the Royal Society.

He wrote a textbook on the theory of heat (1871 ) and an excellent introductory essay on the body and movement (1876 ). In 1871 he was appointed as the first Cavendish Professor of Physics to Cambridge. Maxwell supervised the construction of the Cavendish Laboratory. He oversaw every step in the construction of the building and the purchase of valuable equipment collection with which the laboratory was thanks to the generous founder, the 7th Duke of Devonshire, equipped. One of the last great contributions to science Maxwell was the evaluation of the researches of Henry Cavendish. This revealed that Cavendish had employed, among others, with questions about the mean density of the earth and the composition of the water.

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 proven since in physics as extremely useful. They have been proven in all cases and produced some new laws of electromagnetism and optics, the most important of electromagnetic radiation. The equations are fundamental for radio and television and can be used for the study of X- rays, gamma rays and infrared radiation and other forms of radiation. The Life of James Clerk Maxwell was of his classmate and lifelong friend Professor Lewis Campbell (1830-1908), published in 1882. His collected works, including the series of articles on the properties of matter were published in two volumes by the Cambridge University Press, 1890.

Honors

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

To him, the James Clerk Maxwell Prize for Plasma Physics and the Maxwell medal are named in honor.

Publications (selection)

• On the dynamical theory of gases, Philosophical Transactions of the Royal Society, Volume 157, 1867, pp. 49-88
• Illustrations of the Dynamical Theory of Gases. Philosophical Magazine, Volume 19, 1860, pp. 19-32, Volume 20, 1860, pp. 21-37.
• On Physical Lines of Force, 4 parts, Part 1 The theory of molecular vortices Applied to magnetic phenomena, Philosophical Magazine, Volume 21, 1861, pp. 161-175, Part 2 The theory of molecular vortices Applied to electric currents, ibid., pp. 281-281, 338-345, part 3 The theory of molecular vortices Applied to statical electricity, Phil Mag, Volume 23, 1862, pp. 12-24, Part 4 The theory of molecular vortices Applied to the action of magnetism on polarized light, Phil Mag, Volume 23, 1862, pp. 85-95. German edition: About physical lines of force, Ostwald's Classics # 109 ( Published by Ludwig Boltzmann ), Leipzig: W. Engelmann, 1898

• German edition: About Faraday's lines of force, Leipzig: Wilhelm Engelmann, 1895 ( editor Ludwig Boltzmann )

• German edition: Theory of Heat, Vieweg 1878

• German edition: Textbook of Electrizität and magnetism, 2 volumes, Springer Verlag, Berlin 1883 ( Translator Bernard Weinstein ( 1852-1918 ) )
• Excerpts from James Clerk Maxwell's Electricity and Magnetism, publisher Fritz Emde, translator Hilde Barkhausen, Vieweg 1915

• German edition: The Electrizität in elementary treatment, Vieweg 1883

• Volume 1: 1846-1862. ISBN 0-521-25625-9.
• Volume 2: 1862-1873. ISBN 0-521-25626-7.
• Volume 3: 1874-1879. ISBN 0-521-25627-5.