Famous Physicists Met at Solvay Conference – 7

We have published the 7th of our series where famous physicists met at the Solvay Conference. Thus, we have mentioned all the scientists who contributed greatly to the development of Quantum Mechanics and formed its foundations. Finally, we include 3 scientists, from right to left, in the top row. Scientists Leon Brillouin, Werner Heisenberg, Ralph Howard Fowler.
Famous Physicists Meet at the Solvay Conference – 7 was our last publication. These scientists, whom we frequently refer to in the high school curriculum and at the university level, have almost gathered around Albert Einstein. Now let's get to know these scientists.

Who is Leon Brillouin?

(August 7, 1889 – October 4, 1969) was a French physicist. He made contributions to quantum mechanics, radio wave propagation in the atmosphere, solid state physics, and information theory.
Brillouin was born in Sèvres, near Paris, France. His father, Marcel Brillouin, grandfather Éleuthère Mascart and great-grandfather Charles Briot were also physicists.
From 1908 to 1912 Brillouin studied physics at the École Normale Supérieure in Paris. He worked under Jean Perrin from 1911 until he went to the Ludwig Maximilian University (LMU) in Munich in 1912. He studied theoretical physics with Arnold Sommerfeld at LMU. Just a few months before Brillouin arrived at LMU, Max von Laue had performed his experiment showing X-ray diffraction in a crystal lattice.

Article on the Bohr Model

He returned to France in 1913 to study at the University of Paris, and this year Niels Bohr presented his first paper on the Bohr model of the hydrogen atom. From 1914 to 1919, he served in the army during World War I and developed the valve amplifier with GA Beauvais. At the end of the war, he returned to the University of Paris to continue his studies with Paul Langevin and was awarded the Docteur ès science in 1920. Brillouin's thesis jury was composed of Langevin, Marie Curie and Jean Perrin and was the subject of the thesis. It was on the quantum theory of solids. In his thesis, he proposed an equation of state based on atomic vibrations (phonons) emanating from it. He also studied the propagation of monochromatic light waves and their interaction with acoustic waves, namely the scattering of light with a frequency change known as Brillouin scattering.

After receiving his doctorate, Brillouin became scientific secretary of the reorganized Journal de Physique et le Radium. In 1932 he became deputy director of the physics laboratories at the Collège de France. In 1926, Gregor Wentzel, Hendrik Kramers, and Brillouin independently developed the method known as the WKB method, the classical approximation, and the Wentzel-Kramers-Brillouin approximation, also known as the phase integral method. After the Henri Poincaré Institute was founded in 1928, he was appointed professor to the Chair of Theoretical Physics. During his work on the propagation of electron waves in a crystal lattice, he introduced the concept of Brillouin regions in 1930.

Quantum mechanical perturbation techniques developed by Brillouin and Eugene Wigner resulted in what is known as the Brillouin-Wigner formula.
Since Brillouin's work with Sommerfeld, he has been interested in the diffraction of electromagnetic radiation in a dispersive medium and has done pioneering work. Brillouin, an expert in radio wave propagation, was appointed Managing Director of the French government agency Radiodiffusion Nationale in August 1939, about a month before the war with Germany. In May 1940, upon the collapse of France as part of the government, he retired to Vichy. He resigned six months later and went to the United States.

Until 1942, Brillouin was a visiting professor at the University of Wisconsin-Madison, and then until 1943 a professor at Brown University in Providence, Rhode Island. For the next two years, he worked as a research scientist for the National Defense. Columbia University Research Committee on radar. He was professor of applied mathematics at Harvard University from 1947 to 1949.

From 1952 to 1954, he was a staff member at the IBM Corporation in Poughkeepsie, New York, and at the IBM Watson Laboratory at Columbia University. He became an assistant professor at Columbia University in 1954. He lived in New York until his death in 1969. His wife, Marcelle, died in 1986. Brillouin was the founder of modern solid-state physics, in which he discovered Brillouin regions, among other things. He applied information theory to physics and computer design and introduced the concept of negentropy to illustrate the similarity between entropy and information. Brillouin proposed a solution to the problem of Maxwell's demon. In his book Relativity Re-examined, he called for a "painful and complete reassessment" of the theory of relativity that is "absolutely necessary now."

Who is Werner Heisenberg?

Karl Werner Heisenberg (5 December 1901, Würzburg – 1 February 1976, Munich), German physicist. He discovered the Uncertainty Principle, named after him. He was awarded the 1932 Nobel Prize in Physics for his contributions to the knowledge of atomic structure.

He did research with Arnold Sommerfeld at the University of Munich. He later worked with famous physicists such as Max Born, David Hilbert and Niels Bohr. In 1941 he tried to persuade Bohr to support Germany in the construction of the atomic bomb, but Bohr rejected the offer for moral reasons.

Heisenberg (in 1925) and Erwin Schrödinger (in 1926) very recently independently formulated the quantum (wave) mechanics of the atom differently, but equally in terms of mathematics. These theories were expanded and developed in 1928 by the British theoretical physicist Paul Dirac. In 1927 he was appointed professor of physics at the University of Leipzig. In the same year, he introduced the famous uncertainty principle.

Heisenberg, who became director of the current Max Planck Institute in 1941, signed the founding charter of CERN on behalf of the German government in 1952. He continued to contribute to CERN as a member of the Scientific Policy Committee until 1961 and as a council member until 1963. In 1958, he came up with the formula for the unified field theory, which explained the structure of the fundamental particles inside the atom.

In order to locate an electron, rays with short wavelengths are needed. Since these rays also consist of energy packets (photons), they hit the electron and change its location (Compton Effect). In order not to hit the electron and affect it, rays with very small photons and long wavelengths must be used. In this way, there will be no significant change in the motion of the electron. However, since long wave rays do not provide a strong image, only a very indistinct image is obtained. Thus, it is not possible to locate an element. In general terms; two interconnected quantities cannot be measured simultaneously with high sensitivity (as the sensitivity of measuring one increases, the sensitivity of measuring the other decreases). Energy-time, angular position-angular momentum, position-momentum are these physical quantities, and the product of the measurement errors of these two quantities is larger and equal to Planck's constant.

Heisenberg loved classical music and was an accomplished pianist. His interest in music led him to meet his wife. In January 1937, Heisenberg met Elisabeth Schumacher at a private music recital. Babababba Elisabeth was the daughter of a famous Berlin economics professor. Heisenberg married her on April 29. In 1938, fraternal twins Maria and Wolfgang were born. Over the next 12 years, they had 10 more children, Barbara, Christine, Jochen, Martin, and Verena. Jochen became a professor of physics at the University of New Hampshire.

Who is Ralph Howard Fowler?

(17 January 1889 – 28 July 1944) was an English physicist and astronomer.
Fowler was born on January 17, 1889, in Roydon, Essex, to Howard Fowler of Burnham, Somerset, and Frances Eva, daughter of George Dewhurst, a cotton merchant from Manchester. Initially homeschooled, she later attended Evans' preparatory school at Horris Hill and Winchester College. He was awarded a scholarship to Trinity College, Cambridge, and studied mathematics and was part of the Mathematical Tripos II. He became an assistant in the department.

In 1919, Fowler returned to Trinity and in 1920 was appointed a mathematics lecturer at the university. Here he brought a new approach to physical chemistry by working on thermodynamics and statistical mechanics. He wrote a seminal work on stellar spectra, temperatures, and pressures with Arthur Milne, a comrade during the war. He became a Fellow of the Royal Society in 1925. He became a research advisor to Paul Dirac and worked with him in 1926 on the statistical mechanics of white dwarf stars. He was one of the participants of the fifth Solvay Physics Conference, held at the International Solvay Physics Institute in Belgium in 1927. The field helped establish the validity of electron emission and modern electron band theory. He was the first to formulate and label the zeroth law of thermodynamics in 1931. In 1932 he was elected to the Chair of Theoretical Physics at the Cavendish Laboratory.

In 1939, World War II. When World War II began, he continued his work on the Ordnance Board despite his health, and was selected for scientific liaison with Canada and the United States. He knew America well, held visiting professorships at Princeton and the University of Wisconsin-Madison. He was knighted in 1942 for this liaison work. He returned to England later in the war and worked for the Ordnance Board and the Admiralty until a few weeks before his death in 1944.

Fifteen Royal Society Fellows and three Nobel Laureates (Chandrasekhar, Dirac and Mott) were supervised by Fowler between 1922 and 1939. In addition to Milne, Sir Arthur Eddington, SubrahmanyanChandrasekharHe has worked with Paul Dirac and Sir William McCrea.

It was Fowler who introduced Dirac to quantum theory in 1923. Fowler also put Dirac and Werner Heisenberg in contact with each other through Niels Bohr. He supervised the doctoral studies of 64 students at Cambridge, including John Lennard-Jones, Paul Dirac, and Garrett Birkhoff. The Fowler Islands in Crystal Sound on the Antarctic Peninsula were named in his honor by the UK Antarctic Place-Names Committee.

Source: Wikipedia

 

 

 

📩 25/08/2021 21:08