Portal:Physics
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Physics is the scientific study of matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. It is one of the most fundamental scientific disciplines. A scientist who specializes in the field of physics is called a physicist.
Physics is one of the oldest academic disciplines. Over much of the past two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the Scientific Revolution in the 17th century, these natural sciences branched into separate research endeavors. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in these and other academic disciplines such as mathematics and philosophy.
Advances in physics often enable new technologies. For example, advances in the understanding of electromagnetism, solid-state physics, and nuclear physics led directly to the development of technologies that have transformed modern society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus. (Full article...)
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General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the accepted description of gravitation in modern physics. General relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time, or four-dimensional spacetime. In particular, the curvature of spacetime is directly related to the energy, momentum and stress of whatever is present, including matter and radiation. The relation is specified by the Einstein field equations, a system of second-order partial differential equations.
Newton's law of universal gravitation, which describes gravity in classical mechanics, can be seen as a prediction of general relativity for the almost flat spacetime geometry around stationary mass distributions. Some predictions of general relativity, however, are beyond Newton's law of universal gravitation in classical physics. These predictions concern the passage of time, the geometry of space, the motion of bodies in free fall, and the propagation of light, and include gravitational time dilation, gravitational lensing, the gravitational redshift of light, the Shapiro time delay and singularities/black holes. So far, all tests of general relativity have been in agreement with the theory. The time-dependent solutions of general relativity enable us to extrapolate the history of the universe into the past and future, and have provided the modern framework for cosmology, thus leading to the discovery of the Big Bang and cosmic microwave background radiation. Despite the introduction of a number of alternative theories, general relativity continues to be the simplest theory consistent with experimental data. (Full article...)
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![Image 1 Born, 1930s Max Born (German: [ˈmaks ˈbɔʁn] ⓘ; 11 December 1882 – 5 January 1970) was a German–British theoretical physicist who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics, and supervised the work of a number of notable physicists in the 1920s and 1930s. He shared the 1954 Nobel Prize in Physics with Walther Bothe "for his fundamental research in quantum mechanics, especially in the statistical interpretation of the wave function". Born entered the University of Göttingen in 1904, where he met the three renowned mathematicians Felix Klein, David Hilbert, and Hermann Minkowski. He wrote his Ph.D. thesis on the subject of the stability of elastic wires and tapes, winning the university's Philosophy Faculty Prize. In 1905, he began researching special relativity with Minkowski, and subsequently wrote his habilitation thesis on the Thomson model of the atom. A chance meeting with Fritz Haber in Berlin in 1918 led to discussion of how an ionic compound is formed when a metal reacts with a halogen, which is now known as the Born–Haber cycle. (Full article...)](//upload.wikimedia.org/wikipedia/en/d/d2/Blank.png)
Max Born (German: [ˈmaks ˈbɔʁn] ⓘ; 11 December 1882 – 5 January 1970) was a German–British theoretical physicist who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics, and supervised the work of a number of notable physicists in the 1920s and 1930s. He shared the 1954 Nobel Prize in Physics with Walther Bothe "for his fundamental research in quantum mechanics, especially in the statistical interpretation of the wave function".
Born entered the University of Göttingen in 1904, where he met the three renowned mathematicians Felix Klein, David Hilbert, and Hermann Minkowski. He wrote his Ph.D. thesis on the subject of the stability of elastic wires and tapes, winning the university's Philosophy Faculty Prize. In 1905, he began researching special relativity with Minkowski, and subsequently wrote his habilitation thesis on the Thomson model of the atom. A chance meeting with Fritz Haber in Berlin in 1918 led to discussion of how an ionic compound is formed when a metal reacts with a halogen, which is now known as the Born–Haber cycle. (Full article...) -
Joel S. Levine (born 1942) is an American planetary scientist, author, and research professor in applied science at the College of William & Mary, specializing in the atmospheres of the Moon, Earth, and Mars. He has worked as a senior research scientist at NASA, developing scientific models of the evolution of the Earth's early atmosphere, as well as creating models of the Martian atmosphere for use during the Viking 1 and 2 Mars Orbiter and Lander Missions, and was principal investigator and chief scientist of the proposed ARES Mars Airplane Mission. He also formed and led the "Charters of Freedom Research Team," a group of 12 NASA scientists who worked with the National Archive and Records Administration (NARA) to preserve the United States Declaration of Independence, the Constitution, and the Bill of Rights when small white spots began appearing on the documents in 1988. Levine's past work also includes assisting in the design of the rescue vehicle that saved 33 Chilean miners in the 2010 Copiapó mining accident, as well as original research on the feasibility of the "nuclear winter" hypothesis, and the effects of uncontrolled fires on global warming.
Levine is married to Arlene Spielholz, a former NASA scientist who studied the psychological effects of astronauts spending long time periods in space, and has a daughter and grandson. (Full article...) -
Flerovium is a synthetic chemical element; it has symbol Fl and atomic number 114. It is an extremely radioactive, superheavy element, named after the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research in Dubna, Russia, where the element was discovered in 1999. The lab's name, in turn, honours Russian physicist Georgy Flyorov (Флёров in Cyrillic, hence the transliteration of "yo" to "e"). IUPAC adopted the name on 30 May 2012. The name and symbol had previously been proposed for element 102 (nobelium) but were not accepted by IUPAC at that time.
It is a transactinide in the p-block of the periodic table. It is in period 7 and is the heaviest known member of the carbon group. Initial chemical studies in 2007–2008 indicated that flerovium was unexpectedly volatile for a group 14 element. More recent results show that flerovium's reaction with gold is similar to that of copernicium, showing it is very volatile and may even be gaseous at standard temperature and pressure. Nonetheless, it also seems to show some metallic properties, consistent with it being the heavier homologue of lead. (Full article...) -
Fourteenth-century drawing of angels turning the celestial spheres
Ancient, medieval and Renaissance astronomers and philosophers developed many different theories about the dynamics of the celestial spheres. They explained the motions of the various nested spheres in terms of the materials of which they were made, external movers such as celestial intelligences, and internal movers such as motive souls or impressed forces. Most of these models were qualitative, although a few of them incorporated quantitative analyses that related speed, motive force and resistance. (Full article...) -
The Paranal Observatory of European Southern Observatory shooting a laser guide star to the Galactic Center
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond Earth's atmosphere. Cosmology is the branch of astronomy that studies the universe as a whole.
Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Egyptians, Babylonians, Greeks, Indians, Chinese, Maya, and many ancient indigenous peoples of the Americas. In the past, astronomy included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars. (Full article...) -
Decahedral PtFe1.2 nanoparticle.
A fiveling, also known as a decahedral nanoparticle, a multiply-twinned particle (MTP), a pentagonal nanoparticle, a pentatwin, or a five-fold twin is a type of twinned crystal that can exist at sizes ranging from nanometers to millimetres. It contains five different single crystals arranged around a common axis. In most cases each unit has a face centered cubic (fcc) arrangement of the atoms, although they are also known for other types of crystal structure.
They nucleate at quite small sizes in the nanometer range, but can be grown much larger. They have been found in mineral crystals excavated from mines such as pentagonite or native gold from Ukraine, in rods of metals grown via electrochemical processes and in nanoparticles produced by the condensation of metals either onto substrates or in inert gases. They have been investigated for their potential uses in areas such as improving the efficiency of solar cell or heterogeneous catalysis for more efficient production of chemicals. Information about them is distributed across a diverse range of scientific disciplines, mainly chemistry, materials science, mineralogy, nanomaterials and physics. Because many different names have been used, sometimes the information in the different disciplines or within any one discipline is fragmented and overlapping. (Full article...) -
Harold Melvin Agnew (March 28, 1921 – September 29, 2013) was an American physicist, best known for having flown as a scientific observer on the Hiroshima bombing mission and, later, as the third director of the Los Alamos National Laboratory.
Agnew joined the Metallurgical Laboratory at the University of Chicago in 1942, and helped build Chicago Pile-1, the world's first nuclear reactor. In 1943, he joined the Los Alamos Laboratory, where he worked with the Cockcroft–Walton generator. After the war ended, he returned to the University of Chicago, where he completed his graduate work under Enrico Fermi. (Full article...) -
John von Neumann (/vɒn ˈnɔɪmən/ von NOY-mən; Hungarian: Neumann János Lajos [ˈnɒjmɒn ˈjaːnoʃ ˈlɒjoʃ]; December 28, 1903 – February 8, 1957) was a Hungarian and American mathematician, physicist, computer scientist and engineer. Von Neumann had perhaps the widest coverage of any mathematician of his time, integrating pure and applied sciences and making major contributions to many fields, including mathematics, physics, economics, computing, and statistics. He was a pioneer in building the mathematical framework of quantum physics, in the development of functional analysis, and in game theory, introducing or codifying concepts including cellular automata, the universal constructor and the digital computer. His analysis of the structure of self-replication preceded the discovery of the structure of DNA.
During World War II, von Neumann worked on the Manhattan Project. He developed the mathematical models behind the explosive lenses used in the implosion-type nuclear weapon. Before and after the war, he consulted for many organizations including the Office of Scientific Research and Development, the Army's Ballistic Research Laboratory, the Armed Forces Special Weapons Project and the Oak Ridge National Laboratory. At the peak of his influence in the 1950s, he chaired a number of Defense Department committees including the Strategic Missile Evaluation Committee and the ICBM Scientific Advisory Committee. He was also a member of the influential Atomic Energy Commission in charge of all atomic energy development in the country. He played a key role alongside Bernard Schriever and Trevor Gardner in the design and development of the United States' first ICBM programs. At that time he was considered the nation's foremost expert on nuclear weaponry and the leading defense scientist at the U.S. Department of Defense. (Full article...) -
Rendering of the LIFE.1 fusion power plant. The fusion system is in the large cylindrical containment building in the center.
LIFE, short for Laser Inertial Fusion Energy, was a fusion energy effort run at Lawrence Livermore National Laboratory between 2008 and 2013. LIFE aimed to develop the technologies necessary to convert the laser-driven inertial confinement fusion concept being developed in the National Ignition Facility (NIF) into a practical commercial power plant, a concept known generally as inertial fusion energy (IFE). LIFE used the same basic concepts as NIF, but aimed to lower costs using mass-produced fuel elements, simplified maintenance, and diode lasers with higher electrical efficiency.
Two designs were considered, operated as either a pure fusion or hybrid fusion-fission system. In the former, the energy generated by the fusion reactions is used directly. In the latter, the neutrons given off by the fusion reactions are used to cause fission reactions in a surrounding blanket of uranium or other nuclear fuel, and those fission events are responsible for most of the energy release. In both cases, conventional steam turbine systems are used to extract the heat and produce electricity. (Full article...) -
Matthew Linzee Sands (October 20, 1919 – September 13, 2014) was an American physicist and educator best known as a co-author of the Feynman Lectures on Physics. A graduate of Rice University, Sands served with the Naval Ordnance Laboratory and the Manhattan Project's Los Alamos Laboratory during World War II.
After the war, Sands studied cosmic rays for his doctorate at the Massachusetts Institute of Technology (MIT) under the supervision of Bruno Rossi. Sands went to the California Institute of Technology (Caltech) in 1950, and helped build and operate its 1.5 GeV electron synchrotron. He became deputy director for the construction and early operation of the Stanford Linear Accelerator Center (SLAC) in 1963. Sands later joined the University of California, Santa Cruz (UCSC) as a professor of physics, and served as its Vice Chancellor for Science from 1969 to 1972. In 1998, The American Physical Society awarded him the Robert R. Wilson Prize "for his many contributions to accelerator physics and the development of electron-positron and proton colliders." (Full article...) -
A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or radiology technologists.
CT scanners use a rotating X-ray tube and a row of detectors placed in a gantry to measure X-ray attenuations by different tissues inside the body. The multiple X-ray measurements taken from different angles are then processed on a computer using tomographic reconstruction algorithms to produce tomographic (cross-sectional) images (virtual "slices") of a body. CT scans can be used in patients with metallic implants or pacemakers, for whom magnetic resonance imaging (MRI) is contraindicated. (Full article...) -
Maria Salomea Skłodowska-Curie (Polish: [ˈmarja salɔˈmɛa skwɔˈdɔfska kʲiˈri] ⓘ; née Skłodowska; 7 November 1867 – 4 July 1934), known as Marie Curie (/ˈkjʊəri/ KURE-ee; French: [maʁi kyʁi] ⓘ), was a Polish and naturalised-French physicist and chemist who conducted pioneering research on radioactivity.
She was the first woman to win a Nobel Prize, the first person to win a Nobel Prize twice, and the only person to win a Nobel Prize in two scientific fields. Her husband, Pierre Curie, was a co-winner of her first Nobel Prize, making them the first married couple to win the Nobel Prize and launching the Curie family legacy of five Nobel Prizes. She was, in 1906, the first woman to become a professor at the University of Paris. (Full article...) -
An Andrea Amati violin, which may have been made as early as 1558, making it one of the earliest violins in existence
Violin acoustics is an area of study within musical acoustics concerned with how the sound of a violin is created as the result of interactions between its many parts. These acoustic qualities are similar to those of other members of the violin family, such as the viola.
The energy of a vibrating string is transmitted through the bridge to the body of the violin, which allows the sound to radiate into the surrounding air. Both ends of a violin string are effectively stationary, allowing for the creation of standing waves. A range of simultaneously produced harmonics each affect the timbre, but only the fundamental frequency is heard. The frequency of a note can be raised by the increasing the string's tension, or decreasing its length or mass. The number of harmonics present in the tone can be reduced, for instance by the using the left hand to shorten the string length. The loudness and timbre of each of the strings is not the same, and the material used affects sound quality and ease of articulation. Violin strings were originally made from catgut but are now usually made of steel or a synthetic material. Most strings are wound with metal to increase their mass while avoiding excess thickness. (Full article...) -
Henri Coutard (27 August 1876 – 16 March 1950) was a French radiation therapist. He is known for his studies of radiation therapy for the treatment of laryngeal cancer and the development of the "protracted-fractional method" of radiation dosing.
Born in Marolles-les-Braults in the French department of Sarthe, Coutard attended medical school at University of Paris and graduated in 1902. He served in the French Army and lived for several years in the Jura Mountains before returning to Paris to study the medical applications of radium. During World War I, he worked in one of the radiological ambulance units overseen by the Polish-French physicist and chemist Marie Curie. He became the chief of the X-ray department at the Radium Institute of the University of Paris in 1919, working closely with Claudius Regaud and other scientists. Coutard's early work demonstrating the efficacy of radiating patients with laryngeal cancer led to the adoption of radiation therapy as a primary course of cancer treatment. The protracted-fractional method consisted of long durations of radiation applied over several weeks. (Full article...) -
Luis Walter Alvarez (June 13, 1911 – September 1, 1988) was an American experimental physicist, inventor, and professor of Spanish descent who was awarded the Nobel Prize in Physics in 1968 for his discovery of resonance states in particle physics using the hydrogen bubble chamber. In 2007 the American Journal of Physics commented, "Luis Alvarez was one of the most brilliant and productive experimental physicists of the twentieth century."
After receiving his PhD from the University of Chicago in 1936, Alvarez went to work for Ernest Lawrence at the Radiation Laboratory at the University of California, Berkeley. Alvarez devised a set of experiments to observe K-electron capture in radioactive nuclei, predicted by the beta decay theory but never before observed. He produced tritium using the cyclotron and measured its lifetime. In collaboration with Felix Bloch, he measured the magnetic moment of the neutron. (Full article...)
![Image 1 Born, 1930s Max Born (German: [ˈmaks ˈbɔʁn] ⓘ; 11 December 1882 – 5 January 1970) was a German–British theoretical physicist who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics, and supervised the work of a number of notable physicists in the 1920s and 1930s. He shared the 1954 Nobel Prize in Physics with Walther Bothe "for his fundamental research in quantum mechanics, especially in the statistical interpretation of the wave function". Born entered the University of Göttingen in 1904, where he met the three renowned mathematicians Felix Klein, David Hilbert, and Hermann Minkowski. He wrote his Ph.D. thesis on the subject of the stability of elastic wires and tapes, winning the university's Philosophy Faculty Prize. In 1905, he began researching special relativity with Minkowski, and subsequently wrote his habilitation thesis on the Thomson model of the atom. A chance meeting with Fritz Haber in Berlin in 1918 led to discussion of how an ionic compound is formed when a metal reacts with a halogen, which is now known as the Born–Haber cycle. (Full article...)](/wiki/File:Blank.png)
October anniversaries
- 1 October 1922 - Chen Ning Yang's Birthday
- 1 October 1958 - NASA created to replace NACA
- 7 October 1885 - Niels Bohr's birthday
- 20 October 1984 - Paul Dirac died
General images
The following are images from various physics-related articles on Wikipedia.
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Johannes Kepler's first law of planetary motion states that planets move in elliptical orbits about the Sun. (from History of physics) -
A magnet levitating above a high-temperature superconductor. Today some physicists are working to understand high-temperature superconductivity using the AdS/CFT correspondence. (from Condensed matter physics) -
Sir Isaac Newton (1642–1727) (from History of physics) -
Maxwell's demon, thought experiment by James Clerk Maxwell to describe the kinetic theory of gases and describe how a microscopic creature could lead to violations of the second law of thermodynamics. (from History of physics) -
Albert Einstein (1879–1955), ca. 1905 (from History of physics) -
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Hydrogen emission spectrum is discrete (here in log scale). The lines can only be explained with quantum mechanics. (from History of physics) -
Galileo Galilei (1564–1642), early proponent of the modern scientific worldview and method (from History of physics) -
Magdeburg hemispheres, an experiment by Otto von Guericke where two metal hemispheres are held together by vacuum and cannot be separated even if largue forces are applied. (from History of physics) -
Chien-Shiung Wu worked on parity violation in 1956 and announced her results in January 1957. (from History of physics) -
Composite montage comparing Jupiter (left) and its four Galilean moons (from top: Io, Europa, Ganymede, Callisto) (from History of physics) -
The ancient Greek mathematician Archimedes, developer of ideas regarding fluid mechanics and buoyancy. (from History of physics) -
An engraving of Benjamin Franklin's kite experiment used to study lightning. (from History of physics) -
James Prescott Joule's apparatus for measuring the mechanical equivalent of heat which the "work" of the falling weight is converted into the "heat" of agitation in the water. (from History of physics) -
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1927 Solvay Conference included prominent physicists Albert Einstein, Werner Heisenberg, Max Planck, Hendrik Lorentz, Niels Bohr, Marie Curie, Erwin Schrödinger, Paul Dirac (from History of physics) -
A Feynman diagram representing (left to right) the production of a photon (blue sine wave) from the annihilation of an electron and its complementary antiparticle, the positron. The photon becomes a quark–antiquark pair and a gluon (green spiral) is released. (from History of physics) -
Classical physics (Rayleigh–Jeans law, black line) failed to explain black-body radiation – the so-called ultraviolet catastrophe. The quantum description (Planck's law, colored lines) is said to be modern physics. (from Modern physics) -
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Computer simulation of nanogears made of fullerene molecules. It is hoped that advances in nanoscience will lead to machines working on the molecular scale. (from Condensed matter physics) -
The quantum Hall effect: Components of the Hall resistivity as a function of the external magnetic field (from Condensed matter physics) -
Star maps by the 11th century Chinese polymath Su Song are the oldest known woodblock-printed star maps to have survived to the present day. This example, dated 1092, employs the cylindricalequirectangular projection. (from History of physics) -
The Hindu-Arabic numeral system. The inscriptions on the edicts of Ashoka (3rd century BCE) display this number system being used by the Imperial Mauryas. (from History of physics) -
Image of X-ray diffraction pattern from a protein crystal (from Condensed matter physics) -
Richard Feynman's Los Alamos ID badge (from History of physics) -
The first Bose–Einstein condensate observed in a gas of ultracold rubidium atoms. The blue and white areas represent higher density. (from Condensed matter physics) -
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Marie Skłodowska-Curie
(1867–1934) received Nobel prizes in physics (1903) and chemistry (1911). (from History of physics) -
Heike Kamerlingh Onnes and Johannes van der Waals with the helium liquefactor at Leiden in 1908 (from Condensed matter physics) -
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Newton's cannonball, a though experiment by Newton relating the motion of a projectile and orbiting of planets. (from History of physics) -
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Einstein proposed that gravitation results from masses (or their equivalent energies) curving ("bending") the spacetime in which they exist, altering the paths they follow within it. (from History of physics) -
One possible signature of a Higgs boson from a simulated proton–proton collision. It decays almost immediately into two jets of hadrons and two electrons, visible as lines. (from History of physics) -
Crookes tube used to study cathode rays. It lead to the discovery of the electron by J. J. Thomson. (from History of physics) -
The Standard Model (from History of physics) -
The Voltaic pile, the first battery was invented by Alessandro Volta in 1800 (from History of physics) -
Christiaan Huygens (1629–1695) (from History of physics) -
Classical physics is usually concerned with everyday conditions: speeds are much lower than the speed of light, sizes are much greater than that of atoms, yet very small in astronomical terms. Modern physics, however, is concerned with high velocities, small distances, and very large energies. (from Modern physics)
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Classical physics traditionally includes the fields of mechanics, optics, electricity, magnetism, acoustics and thermodynamics. The term Modern physics is normally used for fields which rely heavily on quantum theory, including quantum mechanics, atomic physics, nuclear physics, particle physics and condensed matter physics. General and special relativity are usually considered to be part of modern physics as well.
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