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Paul Sophus Epstein
Paul Sophus Epstein (; March 20, 1883 – February 8, 1966) was a Russian-American mathematical physicist. He was known for his contributions to fluid dynamics and to the development of quantum mechanics. Early life and studies Paul Epstein's parents, Siegmund Simon Epstein and Sarah Sophia (Lurie) Epstein were of a middle class Jewish family. He said that his mother recognized his potential at the age of four years and predicted that he would be a mathematician. He went to the Hochschule in Minsk, and from 1901 to 1905 studied mathematics and physics at the Imperial University of Moscow under Pyotr Nikolaevich Lebedev. In 1909 he graduated, and became a Privatdozent at the University of Moscow. In 1910 he went to Munich, Germany, to do research under Arnold Sommerfeld, who was his advisor, and Epstein was granted a Ph.D. on a problem in the theory of diffraction of electromagnetic waves. from the Technische Universität München, in 1914. Career At the outbreak of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Warsaw
Warsaw, officially the Capital City of Warsaw, is the capital and List of cities and towns in Poland, largest city of Poland. The metropolis stands on the Vistula, River Vistula in east-central Poland. Its population is officially estimated at 1.86 million residents within a Warsaw metropolitan area, greater metropolitan area of 3.27 million residents, which makes Warsaw the List of cities in the European Union by population within city limits, 6th most-populous city in the European Union. The city area measures and comprises List of districts and neighbourhoods of Warsaw, 18 districts, while the metropolitan area covers . Warsaw is classified as an Globalization and World Cities Research Network#Alpha 2, alpha global city, a major political, economic and cultural hub, and the country's seat of government. It is also the capital of the Masovian Voivodeship. Warsaw traces its origins to a small fishing town in Masovia. The city rose to prominence in the late 16th cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Mechanics
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] |
Old Quantum Theory
The old quantum theory is a collection of results from the years 1900–1925, which predate modern quantum mechanics. The theory was never complete or self-consistent, but was instead a set of heuristic corrections to classical mechanics. The theory has come to be understood as the semi-classical approximation to modern quantum mechanics. The main and final accomplishments of the old quantum theory were the determination of the modern form of the periodic table by Edmund Stoner and the Pauli exclusion principle, both of which were premised on Arnold Sommerfeld's enhancements to the Bohr model of the atom. The main tool of the old quantum theory was the Bohr–Sommerfeld quantization condition, a procedure for selection of certain allowed states of a classical system: the system can then only exist in one of the allowed states and not in any other state. History The old quantum theory was instigated by the 1900 work of Max Planck on the emission and absorption of light in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bohr Model
In atomic physics, the Bohr model or Rutherford–Bohr model was a model of the atom that incorporated some early quantum concepts. Developed from 1911 to 1918 by Niels Bohr and building on Ernest Rutherford's nuclear Rutherford model, model, it supplanted the plum pudding model of J. J. Thomson only to be replaced by the quantum atomic model in the 1920s. It consists of a small, dense nucleus surrounded by orbiting electrons. It is analogy, analogous to the structure of the Solar System, but with attraction provided by Coulomb's law, electrostatic force rather than gravity, and with the electron energies quantized (assuming only discrete values). In the history of atomic physics, it followed, and ultimately replaced, several earlier models, including Joseph Larmor's Solar System model (1897), Jean Perrin's model (1901), the Cubical atom, cubical model (1902), Hantaro Nagaoka's Saturnian model (1904), the plum pudding model (1904), Arthur Haas's quantum model (1910), the Ru ... [...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] |
Enemy Alien
In customary international law, an enemy alien is any alien native, citizen, denizen or subject of any foreign nation or government with which a domestic nation or government is in conflict and who is liable to be apprehended, restrained, secured and removed. Usually, the countries are in a state of declared war. Australia In Australia, in the wake of the outbreak of World War II, Jewish refugees and others fleeing the Nazis were classified as "enemy aliens" upon their arrival in Australia if they arrived with German identity papers. Australian law in 1939 designated people "enemy aliens" if they were Germans or were Australians who had been born in Germany; later, it covered Italians and Japanese as well. The Australian government would therefore intern them, sometimes for years until the war ended, in camps such as the isolated Tatura Internment Camp 3 D which held approximately 300 internees thus deemed "enemy aliens", mostly families, including children as young as two y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting took place mainly in European theatre of World War I, Europe and the Middle Eastern theatre of World War I, Middle East, as well as in parts of African theatre of World War I, Africa and the Asian and Pacific theatre of World War I, Asia-Pacific, and in Europe was characterised by trench warfare; the widespread use of Artillery of World War I, artillery, machine guns, and Chemical weapons in World War I, chemical weapons (gas); and the introductions of Tanks in World War I, tanks and Aviation in World War I, aircraft. World War I was one of the List of wars by death toll, deadliest conflicts in history, resulting in an estimated World War I casualties, 10 million military dead and more than 20 million wounded, plus some 10 million civilian de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proceedings Of The National Academy Of Sciences
''Proceedings of the National Academy of Sciences of the United States of America'' (often abbreviated ''PNAS'' or ''PNAS USA'') is a peer-reviewed multidisciplinary scientific journal. It is the official journal of the National Academy of Sciences, published since 1915, and publishes original research, scientific reviews, commentaries, and letters. According to ''Journal Citation Reports'', the journal has a 2022 impact factor of 9.4. ''PNAS'' is the second most cited scientific journal, with more than 1.9 million cumulative citations from 2008 to 2018. In the past, ''PNAS'' has been described variously as "prestigious", "sedate", "renowned" and "high impact". ''PNAS'' is a delayed open-access journal, with an embargo period of six months that can be bypassed for an author fee ( hybrid open access). Since September 2017, open access articles are published under a Creative Commons license. Since January 2019, ''PNAS'' has been online-only, although print issues are available ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffraction
Diffraction is the deviation of waves from straight-line propagation without any change in their energy due to an obstacle or through an aperture. The diffracting object or aperture effectively becomes a secondary source of the Wave propagation, propagating wave. Diffraction is the same physical effect as Wave interference, interference, but interference is typically applied to superposition of a few waves and the term diffraction is used when many waves are superposed. Italian scientist Francesco Maria Grimaldi coined the word ''diffraction'' and was the first to record accurate observations of the phenomenon in 1660 in science, 1660. In classical physics, the diffraction phenomenon is described by the Huygens–Fresnel principle that treats each point in a propagating wavefront as a collection of individual spherical wavelets. The characteristic pattern is most pronounced when a wave from a Coherence (physics), coherent source (such as a laser) encounters a slit/aperture tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Munich
Munich is the capital and most populous city of Bavaria, Germany. As of 30 November 2024, its population was 1,604,384, making it the third-largest city in Germany after Berlin and Hamburg. Munich is the largest city in Germany that is not a state of its own. It ranks as the 11th-largest city in the European Union. The metropolitan area has around 3 million inhabitants, and the broader Munich Metropolitan Region is home to about 6.2 million people. It is the List of EU metropolitan regions by GDP#2021 ranking of top four German metropolitan regions, third largest metropolitan region by GDP in the European Union. Munich is located on the river Isar north of the Alps. It is the seat of the Upper Bavaria, Upper Bavarian administrative region. With 4,500 people per km2, Munich is Germany's most densely populated municipality. It is also the second-largest city in the Bavarian language, Bavarian dialect area after Vienna. The first record of Munich dates to 1158. The city ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Privatdozent
''Privatdozent'' (for men) or ''Privatdozentin'' (for women), abbreviated PD, P.D. or Priv.-Doz., is an academic title conferred at some European universities, especially in German-speaking countries, to someone who holds certain formal qualifications that denote an ability (''facultas docendi'') and permission to teach ('' venia legendi'') a designated subject at the highest level. To be granted the title Priv.-Doz. by a university, a recipient has to fulfill the criteria set by the university which usually require excellence in research, teaching, and further education. In its current usage, the title indicates that the holder has completed their habilitation and is therefore granted permission to teach and examine students independently without having a full professorship (chair). With respect to the level of academic achievement, the title of ''Privatdozent'' is comparable to that of an Associate Professor (United States), Senior Lecturer (United Kingdom), or ''maître de con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyotr Nikolaevich Lebedev
Pyotr Nikolaevich Lebedev (; 24 February 1866 – 1 March 1912) was a Russian physicist. His name was also transliterated as Peter Lebedew and Peter Lebedev. Lebedev was the creator of the first scientific school in Russia. Career Lebedev made his doctoral degree in Strasbourg under the supervision of August Kundt in 1887–1891. In 1891, he started working in Moscow State University in the group of Alexander Stoletov. There he made his famous experimental studies of electromagnetic waves. Along with Indian physicist Jagadish Chandra Bose he was one of the first to investigate millimeter waves, generating 50 GHz (6 mm) microwaves beginning in 1895 with a spark oscillator made of two platinum cylinders 1.5 cm long and 0.5 diameter immersed in kerosene at the focus of a parabolic reflector, and detecting the waves with an iron- constantan thermocouple detector.A. A. Kostenko, A. I. Nosich, P. F. Goldsmith, "Historical background and development of Soviet qu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
