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Giulio Racah
Giulio (Yoel) Racah (; February 9, 1909 – August 28, 1965) was an Italian–Israeli physicist and mathematician. He was Acting President of the Hebrew University of Jerusalem from 1961 to 1962. The crater Racah on the Moon is named after him. Biography Giulio (Yoel) Racah was born in Florence, Italy. On his mother's side, Racah's family claimed to trace its ancestry in Italy back to the destruction of the Second Temple. He earned his Doctorate from the University of Florence in 1930, and continued his studies at Rome with Enrico Fermi. In 1939, due to application of Anti-Jewish laws in Italy, Racah emigrated to the British Mandate of Palestine. In the 1948 Arab–Israeli War, Racah served as deputy commander of the Israeli forces defending Mount Scopus. Racah died at the age of 56, apparently asphyxiated by gas from a faulty heater while visiting Florence. Academic and scientific career In 1937 Racah was appointed Professor of Physics at the University of Pisa. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Florence
Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025. Florence was a centre of Middle Ages, medieval European trade and finance and one of the wealthiest cities of that era. It is considered by many academics to have been the birthplace of the Renaissance, becoming a major artistic, cultural, commercial, political, economic and financial center. During this time, Florence rose to a position of enormous influence in Italy, Europe, and beyond. Its turbulent political history includes periods of rule by the powerful House of Medici, Medici family and numerous religious and republican revolutions. From 1865 to 1871 the city served as the capital of the Kingdom of Italy. The Florentine dialect forms the base of Italian language, standard Italian and it became the language of culture throughout Italy due to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Pisa
The University of Pisa (, UniPi) is a public university, public research university in Pisa, Italy. Founded in 1343, it is one of the oldest universities in Europe. Together with Scuola Normale Superiore di Pisa and Sant'Anna School of Advanced Studies, it is part of the Pisa University System. History The Origins The University of Pisa was officially founded in 1343, although various scholars place its origins in the 11th century. It is certain, however, that from the middle of the 12th century Pisa had a “Universitas” in the original sense of the word, that is, a group of students who gathered around masters. It was during this period that Leonardo Fibonacci was born and worked. He was one of the greatest mathematicians in history who, through his work, synthesized the spirit and processes of Greek geometry and the tools of Arabic mathematics for the first time in Europe. The papal seal “In Supremae dignitatis”, issued by Pope Clement VI on 3 September 1343, grant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Racah Polynomials
In mathematics, Racah polynomials are orthogonal polynomials named after Giulio Racah, as their orthogonality relations are equivalent to his orthogonality relations for Racah coefficients. The Racah polynomials were first defined by and are given by :p_n(x(x+\gamma+\delta+1)) = _4F_3\left begin -n &n+\alpha+\beta+1&-x&x+\gamma+\delta+1\\ \alpha+1&\gamma+1&\beta+\delta+1\\ \end;1\right Orthogonality :\sum_^N\operatorname_n(x;\alpha,\beta,\gamma,\delta) \operatorname_m(x;\alpha,\beta,\gamma,\delta)\frac \omega_y=h_n\operatorname_, :when \alpha+1=-N, :where \operatorname is the Racah polynomial, :x=y(y+\gamma+\delta+1), :\operatorname_ is the Kronecker delta function and the weight functions are :\omega_y=\frac, :and :h_n=\frac\frac\frac, :(\cdot)_n is the Pochhammer symbol. Rodrigues-type formula :\omega(x;\alpha,\beta,\gamma,\delta)\operatorname_n(\lambda(x);\alpha,\beta,\gamma,\delta)=(\gamma+\delta+1)_n\frac\omega(x;\alpha+n,\beta+n,\gamma+n,\delta), :where \nabla is the bac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Racah Parameter
The Racah parameters are a set of parameters used in atomic and molecular spectroscopy to describe the amount of total electrostatic repulsion in an atom that has multiple electrons. When an atom has more than one electron, there will be some electrostatic repulsion between the electrons. The amount of repulsion varies from atom to atom, depending upon the number of electrons, their spin, and the orbitals that they occupy. The total repulsion can be expressed in terms of three parameters ''A'', ''B'' and ''C'' which are known as the ''Racah parameters'' after Giulio Racah, who first described them. They are generally obtained empirically from gas-phase spectroscopic studies of atoms. They are often used in transition-metal chemistry to describe the repulsion energy associated with an electronic term. For example, the interelectronic repulsion of a 3P term is ''A'' + 7''B'', and of a 3F term is ''A'' - 8''B'', and the difference between them is therefore 15''B''. Definition The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Racah W-coefficient
Racah's W-coefficients were introduced by Giulio Racah in 1942. These coefficients have a purely mathematical definition. In physics they are used in calculations involving the quantum mechanics, quantum mechanical description of angular momentum, for example in atomic theory. The coefficients appear when there are three sources of angular momentum in the problem. For example, consider an atom with one electron in an atomic orbital, s orbital and one electron in a atomic orbital, p orbital. Each electron has electron spin angular momentum and in addition the p orbital has orbital angular momentum (an s orbital has zero orbital angular momentum). The atom may be described by ''LS'' coupling or by ''jj'' coupling as explained in the article on angular momentum coupling. The transformation between the wave functions that correspond to these two couplings involves a Racah W-coefficient. Apart from a phase factor, Racah's W-coefficients are equal to Wigner's 6-j symbols, so any equation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Israel Prize
The Israel Prize (; ''pras israél'') is an award bestowed by the State of Israel, and regarded as the state's highest cultural honor. History Prior to the Israel Prize, the most significant award in the arts was the Dizengoff Prize and in Israeli literature, literature the Bialik Prize, awarded by the Tel Aviv municipality annually since 1930s. The Israel Prize is awarded annually, on Yom Ha'atzmaut, Israeli Independence Day, in a state ceremony in Jerusalem, in the presence of the President of Israel, President, the Prime Minister of Israel, Prime Minister, the List of Knesset speakers, Speaker of the Knesset (Israel's legislature), and the Supreme Court of Israel, Supreme Court President. The prize was established in 1953 at the initiative of the Education Minister of Israel, Minister of Education Ben-Zion Dinor, who himself went on to win the prize in 1958 and 1973. Awarding the prize The prize is awarded in the following four areas, with the precise subfields changing from y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ugo Fano
Ugo Fano (July 28, 1912 – February 13, 2001) was an Italian American physicist, notable for contributions to theoretical physics. Biography Ugo Fano was born into a wealthy Jewish family in Turin, Italy. His father was Gino Fano, a professor of mathematics. University studies Fano earned his doctorate in mathematics at the University of Turin in 1934, under Enrico Persico, with a thesis entitled ''Sul Calcolo dei Termini Spettrali e in Particolare dei Potenziali di Ionizzazione Nella Meccanica Quantistica'' (''On the Quantum Mechanical Calculation Spectral Terms and their Extension to Ionization''). As part of his PhD examination he also made two oral presentations entitled: ''Sulle Funzioni di Due o Più Variabili Complesse'' (''On the functions of two or more complex variables'') and ''Le Onde Elettromagnetiche di Maggi: Le Connessioni Asimmetriche Nella Geometria Non Riemanniana'' (''Maggi electromagnetic waves: asymmetric connections in non-Riemannian geometry''). E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Structure
Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium, and any atom that contains 29 protons is copper. Atoms with the same number of protons but a different number of neutrons are called isotopes of the same element. Atoms are extremely small, typically around 100 picometers across. A human hair is about a million carbon atoms wide. Atoms are smaller than the shortest wavelength of visible light, which means humans cannot see atoms with conventional microscopes. They are so small that accurately predicting their behavior using classical physics is not possible due to quantum effects. More than 99.94% of an atom's mass is in the nucleus. Protons have a positive electric charge and n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Energy Level
A quantum mechanics, quantum mechanical system or particle that is bound state, bound—that is, confined spatially—can only take on certain discrete values of energy, called energy levels. This contrasts with classical mechanics, classical particles, which can have any amount of energy. The term is commonly used for the energy levels of the electrons in atoms, ions, or molecules, which are bound by the electric field of the atomic nucleus, nucleus, but can also refer to energy levels of nuclei or molecular vibration, vibrational or rotational energy levels in molecules. The energy spectrum of a system with such discrete energy levels is said to be Quantization (physics), quantized. In chemistry and atomic physics, an electron shell, or principal energy level, may be thought of as the orbit of one or more electrons around an atom's atomic nucleus, nucleus. The closest shell to the nucleus is called the "1 shell" (also called "K shell"), followed by the "2 shell" (or "L shell"), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectroscopy
Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectroscopy, primarily in the electromagnetic spectrum, is a fundamental exploratory tool in the fields of astronomy, chemistry, materials science, and physics, allowing the composition, physical structure and electronic structure of matter to be investigated at the atomic, molecular and macro scale, and over astronomical distances. Historically, spectroscopy originated as the study of the wavelength dependence of the absorption by gas phase matter of visible light dispersed by a prism. Current applications of spectroscopy include biomedical spectroscopy in the areas of tissue analysis and medical imaging. Matter waves and acoustic waves can also be considered forms of radiative energy, and recently gravitational waves have been associa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Physics
Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is the foundation of all quantum physics, which includes quantum chemistry, quantum field theory, quantum technology, and quantum information science. Quantum mechanics can describe many systems that classical physics cannot. Classical physics can describe many aspects of nature at an ordinary (macroscopic and Microscopic scale, (optical) microscopic) scale, but is not sufficient for describing them at very small submicroscopic (atomic and subatomic) scales. Classical mechanics can be derived from quantum mechanics as an approximation that is valid at ordinary scales. Quantum systems have Bound state, bound states that are Quantization (physics), quantized to Discrete mathematics, discrete values of energy, momentum, angular momentum, and ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Racah Institute Of Physics
The Racah Institute of Physics () is an institute at the Hebrew University of Jerusalem, part of the faculty of Mathematics and Natural Sciences on the Edmund J. Safra Campus in the Givat Ram neighborhood of Jerusalem. The institute is the center for all research and teaching in the various fields of physics at the Hebrew University. These include astrophysics, high energy physics, quantum physics, nuclear physics, solid state physics, laser and plasma physics, biophysics, non-linear and statistical physics, and nanophysics. Both experimental and theoretical research is carried on in these fields. History In 1913, before the opening of the Hebrew University, first steps towards physics research in Jerusalem were taken by Chaim Weizmann. Weizmann, the president of the Zionist Organisation, and the major figure in the planning and founding of the Hebrew University contacted Leonard Ornstein, the known physicist from Utrecht, the Netherlands, to prepare plans for physics researc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
