Portal:Physics
The Physics Portal
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. Physics 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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In algebraic geometry and theoretical physics, mirror symmetry is a relationship between geometric objects called Calabi–Yau manifolds. The term refers to a situation where two Calabi–Yau manifolds look very different geometrically but are nevertheless equivalent when employed as extra dimensions of string theory.
Early cases of mirror symmetry were discovered by physicists. Mathematicians became interested in this relationship around 1990 when Philip Candelas, Xenia de la Ossa, Paul Green, and Linda Parkes showed that it could be used as a tool in enumerative geometry, a branch of mathematics concerned with counting the number of solutions to geometric questions. Candelas and his collaborators showed that mirror symmetry could be used to count rational curves on a Calabi–Yau manifold, thus solving a longstanding problem. Although the original approach to mirror symmetry was based on physical ideas that were not understood in a mathematically precise way, some of its mathematical predictions have since been proven rigorously. (Full article...)
Did you know -
- ... that lasers can be used to separate two isotopes very efficiently?
- ... that your feet are slightly younger than your head, because time runs slow at a lower Gravitational Potential. This is a consequence of Gravitational Time Dilation
- ...that Max Planck created a system of measurement based solely on natural units?
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James Clerk Maxwell FRS FRSE (13 June 1831 – 5 November 1879) was a Scottish[1] theoretical physicist.[2] His most prominent achievement was formulating classical electromagnetic theory. This unites all previously unrelated observations, experiments, and equations of electricity, magnetism, and optics into a consistent theory.[3] Maxwell's equations demonstrate that electricity, magnetism and light are all manifestations of the same phenomenon, namely the electromagnetic field. Subsequently, all other classic laws or equations of these disciplines became simplified cases of Maxwell's equations. Maxwell's achievements concerning electromagnetism have been called the "second great unification in physics",[4] after the first one realised by Isaac Newton.
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Hugh Bradner (November 5, 1915 – May 5, 2008) was an American physicist at the University of California who is credited with inventing the neoprene wetsuit, which helped to revolutionize scuba diving and surfing.
A graduate of Ohio's Miami University, he received his doctorate from California Institute of Technology in Pasadena, California, in 1941. He worked at the US Naval Ordnance Laboratory during World War II, where he researched naval mines. In 1943, he was recruited by Robert Oppenheimer to join the Manhattan Project at the Los Alamos Laboratory. There, he worked with scientists including Luis Alvarez, John von Neumann and George Kistiakowsky on the development of the high explosives and exploding-bridgewire detonators required by atomic bombs. (Full article...) -
The maximum sustained wind associated with a tropical cyclone is a common
indicator of the intensity of the storm. Within a mature tropical cyclone, it is found within the eyewall at a certain distance from the center, known as the radius of maximum wind, or RMW. Unlike gusts, the value of these winds are determined via their sampling and averaging the sampled results over a period of time. Wind measuring has been standardized globally to reflect the winds at 10 metres (33 ft) above mean sea level, and the maximum sustained wind represents the highest average wind over either a one-minute (US) or ten-minute time span (see the definition, below), anywhere within the tropical cyclone. Surface winds are highly variable due to friction between the atmosphere and the Earth's surface, as well as near hills and mountains over land.
Over the ocean, satellite imagery is often used to estimate the maximum sustained winds within a tropical cyclone. Land, ship, aircraft reconnaissance observations, and radar imagery can also estimate this quantity, when available. This value helps determine the damage potential of a tropical cyclone, through use of such scales as the Saffir–Simpson scale. (Full article...) -
Aage Niels Bohr (Danish: [ˈɔːwə ˈne̝ls ˈpoɐ̯ˀ] ⓘ; 19 June 1922 – 8 September 2009) was a Danish nuclear physicist who shared the Nobel Prize in Physics in 1975 with Ben Roy Mottelson and James Rainwater "for the discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection". His father was Niels Bohr.
Starting from Rainwater's concept of an irregular-shaped liquid drop model of the nucleus, Bohr and Mottelson developed a detailed theory that was in close agreement with experiments. (Full article...) -
Emilio Gino Segrè (Italian: [seˈgrɛ]; 1 February 1905 – 22 April 1989) was an Italian and naturalized-American physicist and Nobel laureate, who discovered the elements technetium and astatine, and the antiproton, a subatomic antiparticle, for which he was awarded the Nobel Prize in Physics in 1959 along with Owen Chamberlain.
Born in Tivoli, near Rome, Segrè studied engineering at the University of Rome La Sapienza before taking up physics in 1927. Segrè was appointed assistant professor of physics at the University of Rome in 1932 and worked there until 1936, becoming one of the Via Panisperna boys. From 1936 to 1938 he was director of the Physics Laboratory at the University of Palermo. After a visit to Ernest O. Lawrence's Berkeley Radiation Laboratory, he was sent a molybdenum strip from the laboratory's cyclotron accelerator in 1937, which was emitting anomalous forms of radioactivity. Using careful chemical and theoretical analysis, Segrè was able to prove that some of the radiation was being produced by a previously unknown element, named technetium, the first artificially synthesized chemical element that does not occur in nature. (Full article...) -
Hans Albrecht Bethe (/ˈbɛθə/; German: [ˈhans ˈbeːtə] ⓘ; July 2, 1906 – March 6, 2005) was a German-American physicist who made major contributions to nuclear physics, astrophysics, quantum electrodynamics and solid-state physics, and received the Nobel Prize in Physics in 1967 for his work on the theory of stellar nucleosynthesis. For most of his career, Bethe was a professor at Cornell University.
In 1939, Bethe published a paper which established the CNO cycle as the primary energy source for heavier stars in the main sequence classification of stars, which earned him a Nobel Prize in 1967. During World War II, Bethe was head of the Theoretical Division at the secret Los Alamos National Laboratory that developed the first atomic bombs. There he played a key role in calculating the critical mass of the weapons and developing the theory behind the implosion method used in both the Trinity test and the "Fat Man" weapon dropped on Nagasaki in August 1945. (Full article...) -
The Nobel Prize in Physics (Swedish: Nobelpriset i fysik) is an annual award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions to mankind in the field of physics. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901, the others being the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and Nobel Prize in Physiology or Medicine. Physics is traditionally the first award presented in the Nobel Prize ceremony.
The prize consists of a medal along with a diploma and a certificate for the monetary award. The front side of the medal displays the same profile of Alfred Nobel depicted on the medals for Physics, Chemistry, and Literature. (Full article...) -
Boyce Dawkins McDaniel (June 11, 1917 – May 8, 2002) was an American nuclear physicist who worked on the Manhattan Project and later directed the Cornell University Laboratory of Nuclear Studies (LNS). McDaniel was skilled in constructing "atom smashing" devices to study the fundamental structure of matter and helped to build the most powerful particle accelerators of his time. Together with his graduate student, he invented the pair spectrometer.
During World War II, McDaniel used his electronics expertise to help develop cyclotrons used to separate Uranium isotopes. McDaniel is also noted as having performed the final check on the first atomic bomb prior to its detonation in the Trinity test, during a lightning storm. (Full article...) -
PSR B1937+21 is a pulsar located in the constellation Vulpecula a few degrees in the sky away from the first discovered pulsar, PSR B1919+21. The name PSR B1937+21 is derived from the word "pulsar" and the declination and right ascension at which it is located, with the "B" indicating that the coordinates are for the 1950.0 epoch. PSR B1937+21 was discovered in 1982 by Don Backer, Shri Kulkarni, Carl Heiles, Michael Davis, and Miller Goss.
It is the first discovered millisecond pulsar, with a rotational period of 1.557708 milliseconds, meaning it completes almost 642 rotations per second. This period was far shorter than astronomers considered pulsars capable of reaching, and led to the suggestion that pulsars can be spun-up by accreting mass from a companion. (Full article...) -
Stanisław Marcin Ulam (Polish: [sta'ɲiswaf 'mart͡ɕin 'ulam]; 13 April 1909 – 13 May 1984) was a Polish mathematician, nuclear physicist and computer scientist. He participated in the Manhattan Project, originated the Teller–Ulam design of thermonuclear weapons, discovered the concept of the cellular automaton, invented the Monte Carlo method of computation, and suggested nuclear pulse propulsion. In pure and applied mathematics, he proved a number of theorems and proposed several conjectures.
Born into a wealthy Polish Jewish family in Lemberg, Austria-Hungary; Ulam studied mathematics at the Lwów Polytechnic Institute, where he earned his PhD in 1933 under the supervision of Kazimierz Kuratowski and Włodzimierz Stożek. In 1935, John von Neumann, whom Ulam had met in Warsaw, invited him to come to the Institute for Advanced Study in Princeton, New Jersey, for a few months. From 1936 to 1939, he spent summers in Poland and academic years at Harvard University in Cambridge, Massachusetts, where he worked to establish important results regarding ergodic theory. On 20 August 1939, he sailed for the United States for the last time with his 17-year-old brother Adam Ulam. He became an assistant professor at the University of Wisconsin–Madison in 1940, and a United States citizen in 1941. (Full article...) -
Experiments on European robins, which are migratory, suggest their magnetic sense makes use of the quantum radical pair mechanism.
Magnetoreception is a sense which allows an organism to detect the Earth's magnetic field. Animals with this sense include some arthropods, molluscs, and vertebrates (fish, amphibians, reptiles, birds, and mammals). The sense is mainly used for orientation and navigation, but it may help some animals to form regional maps. Experiments on migratory birds provide evidence that they make use of a cryptochrome protein in the eye, relying on the quantum radical pair mechanism to perceive magnetic fields. This effect is extremely sensitive to weak magnetic fields, and readily disturbed by radio-frequency interference, unlike a conventional iron compass.
Birds have iron-containing materials in their upper beaks. There is some evidence that this provides a magnetic sense, mediated by the trigeminal nerve, but the mechanism is unknown. (Full article...) -
Edward Creutz (January 23, 1913 – June 27, 2009) was an American physicist who worked on the Manhattan Project at the Metallurgical Laboratory and the Los Alamos Laboratory during World War II. After the war he became a professor of physics at the Carnegie Institute of Technology. He was Vice President of Research at General Atomics from 1955 to 1970. He published over 65 papers on botany, physics, mathematics, metallurgy and science policy, and held 18 patents relating to nuclear energy.
A graduate of the University of Wisconsin–Madison, Creutz helped Princeton University build its first cyclotron. During World War II he worked on nuclear reactor design under Eugene Wigner at the Metallurgical Laboratory, designing the cooling system for the first water-cooled reactors. He led a group that studied the metallurgy of uranium and other elements used in reactor designs. In October 1944, he moved to the Los Alamos Laboratory, where he became a group leader. (Full article...) -
The nucleon magnetic moments are the intrinsic magnetic dipole moments of the proton and neutron, symbols μp and μn. The nucleus of an atom comprises protons and neutrons, both nucleons that behave as small magnets. Their magnetic strengths are measured by their magnetic moments. The nucleons interact with normal matter through either the nuclear force or their magnetic moments, with the charged proton also interacting by the Coulomb force.
The proton's magnetic moment was directly measured in 1933 by Otto Stern team in University of Hamburg. While the neutron was determined to have a magnetic moment by indirect methods in the mid-1930s, Luis Alvarez and Felix Bloch made the first accurate, direct measurement of the neutron's magnetic moment in 1940. The proton's magnetic moment is exploited to make measurements of molecules by proton nuclear magnetic resonance. The neutron's magnetic moment is exploited to probe the atomic structure of materials using scattering methods and to manipulate the properties of neutron beams in particle accelerators. (Full article...) -
Subtle is the Lord: The Science and the Life of Albert Einstein is a biography of Albert Einstein written by Abraham Pais. First published in 1982 by Oxford University Press, the book is one of the most acclaimed biographies of the scientist. This was not the first popular biography of Einstein, but it was the first to focus on his scientific research as opposed to his life as a popular figure. Pais, renowned for his work in theoretical particle physics, was a friend of Einstein's at the Institute for Advanced Study in his early career. Originally published in English in the United States and the United Kingdom, the book has translations in over a dozen languages. Pais later released a sequel to the book in 1994 titled Einstein Lived Here and, after his death in 2000, the University Press released a posthumous reprint of the biography in 2005, with a new foreword by Roger Penrose. Considered very popular for a science book, the biography sold tens of thousands of copies of both paperback and hardcover versions in its first year. The book has received many reviews and, the year after its initial publication, it won both the 1983 National Book Award for Nonfiction, in Science (Hardcover), and the 1983 Science Writing Award. (Full article...)
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Styrofoam peanuts clinging to a cat's fur due to static electricity.
The triboelectric effect (also known as triboelectricity, triboelectric charging, triboelectrification, or tribocharging) describes electric charge transfer between two objects when they contact or slide against each other. It can occur with different materials, such as the sole of a shoe on a carpet, or between two pieces of the same material. It is ubiquitous, and occurs with differing amounts of charge transfer (tribocharge) for all solid materials. There is evidence that tribocharging can occur between combinations of solids, liquids and gases, for instance liquid flowing in a solid tube or an aircraft flying through air.
Often static electricity is a consequence of the triboelectric effect when the charge stays on one or both of the objects and is not conducted away. The term triboelectricity has been used to refer to the field of study or the general phenomenon of the triboelectric effect, or to the static electricity that results from it. When there is no sliding, tribocharging is sometimes called contact electrification, and any static electricity generated is sometimes called contact electricity. The terms are often used interchangeably, and may be confused. (Full article...) -
John Harmen "Jack" Marburger III (February 8, 1941 – July 28, 2011) was an American physicist who directed the Office of Science and Technology Policy in the administration of President George W. Bush, serving as the Science Advisor to the President. His tenure was marred by controversy regarding his defense of the administration against allegations from over two dozen Nobel Laureates, amongst others, that scientific evidence was being suppressed or ignored in policy decisions, including those relating to stem cell research and global warming. However, he has also been credited with keeping the political effects of the September 11 attacks from harming science research—by ensuring that tighter visa controls did not hinder the movement of those engaged in scientific research—and with increasing awareness of the relationship between science and government. He also served as the President of Stony Brook University from 1980 until 1994, and director of Brookhaven National Laboratory from 1998 until 2001. (Full article...)
February anniversaries
- 15 February 1564 – Galileo Galilei's birthday
- 18 February 1745 – Alessandro Volta's birthday
- 15 February 1786 – Cat's Eye Nebula discovered
- 18 February 1838 – Ernst Mach's birthday
- 11 February 1847 – Thomas Edison's birthday
- 23 February 1855 – Carl Friedrich Gauss's death
- 22 February 1875 – Heinrich Hertz's birthday
- 28 February 1901 – Linus Pauling's birthday
- 18 February 1967 – J. Robert Oppenheimer's death
- 13 February 1910 – William Shockley's birthday
- 15 February 1988 – Richard Feynman died
- 28 February 2020 – Freeman Dyson's death
General images
The following are images from various physics-related articles on Wikipedia.
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An artist's rendition of Kepler-62f, a potentially habitable exoplanet discovered using data transmitted by the Kepler space telescope, named after Kepler. (from History of physics) -
The Polish astronomer Nicolaus Copernicus (1473–1543) is remembered for his development of a heliocentric model of the Solar System. (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 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) -
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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Daniel Bernoulli (1700–1782) (from History of physics) -
Chien-Shiung Wu worked on parity violation in 1956 and announced her results in January 1957. (from History of physics) -
J. J. Thomson (1856–1940) discovered the electron and isotopy and also invented the mass spectrometer. He was awarded the Nobel Prize in Physics in 1906. (from History of physics) -
Max Planck (1858–1947) (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) -
Rudolf Clausius (1822–1888) (from History of physics) -
Richard Feynman's Los Alamos ID badge (from History of physics) -
James Clerk Maxwell (1831–1879) (from History of physics) -
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The Standard Model (from History of physics) -
Johannes Kepler.(1571–1630) (from History of physics) -
René Descartes (1596–1650) (from History of physics) -
Albert Einstein (1879–1955), photographed here in around 1905 (from History of physics) -
Ludwig Boltzmann (1844–1906) (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) -
Galileo Galilei, early proponent of the modern scientific worldview and method (1564–1642) (from History of physics) -
Einstein proposed that gravitation is a result of masses (or their equivalent energies) curving ("bending") the spacetime in which they exist, altering the paths they follow within it. (from History of physics) -
The ancient Greek mathematician Archimedes, developer of ideas regarding fluid mechanics and buoyancy. (from History of physics) -
Sir Isaac Newton (1642–1727) (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) -
William Thomson (Lord Kelvin)
(1824–1907) (from History of physics) -
Image of X-ray diffraction pattern from a protein crystal (from Condensed matter physics) -
Gottfried Leibniz (1646–1716) (from History of physics) -
Heike Kamerlingh Onnes and Johannes van der Waals with the helium liquefactor at Leiden in 1908 (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) -
Werner Heisenberg (1901–1976) (from History of physics) -
Alessandro Volta (1745–1827) (from History of 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) -
Michael Faraday (1791–1867) (from History of 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) -
Christiaan Huygens (1629–1695) (from History of physics) -
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A composite montage comparing Jupiter (lefthand side) and its four Galilean moons (top to bottom: Io, Europa, Ganymede, Callisto) (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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Marie Skłodowska-Curie
(1867–1934) was awarded two Nobel prizes, Physics (1903) and Chemistry (1911) (from History of physics)
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Categories
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Physics topics
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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Sources
- ^ "James Clerk Maxwell". Encyclopædia Britannica. Retrieved 24 February 2010.
Scottish physicist best known for his formulation of electromagnetic theory
- ^ James Clerk Maxwell
- ^ "James Clerk Maxwell". IEEE Global History Network. 2011. Retrieved 2011-06-21.
- ^ Nahin, P.J. (1992). "Maxwell's grand unification". IEEE Spectrum. 29 (3): 45. doi:10.1109/6.123329.
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