Back Portaal:Fisika Afrikaans بوابة:الفيزياء Arabic قيسارية:لفيزيك ARY بوابة:الفيزيا ARZ Portal:Fizika Azerbaijani Портал:Физика Bulgarian প্রবেশদ্বার:পদার্থবিজ্ঞান Bengali/Bangla Porched:Fizik Breton Portal:Fizika BS Portal:Física Catalan
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...)
Featured article -
This is a Featured article, which represents some of the best content on English Wikipedia.
Various cosmological models of the Big Bang explain the evolution of the observable universe from the earliest known periods through its subsequent large-scale form. These models offer a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, and large-scale structure. The uniformity of the universe, known as the flatness problem, is explained through cosmic inflation: a sudden and very rapid expansion of space during the earliest moments. (Full article...)
Did you know -
- ...that if you ever saw Jupiter's magnetic field from Earth, it would appear five times larger than the full moon?
- ...that the impact of a raindrop would be fatal if not for the property of fluid flow known as terminal velocity?
- ...that transits of Venus occur in a 243-year cycle?
Selected image -
Difference between classical and modern physics
While physics aims to discover universal laws, its theories lie in explicit domains of applicability. Loosely speaking, the laws of classical physics accurately describe systems whose important length scales are greater than the atomic scale and whose motions are much slower than the speed of light. Outside of this domain, observations do not match their predictions. Albert Einstein contributed the framework of special relativity, which replaced notions of absolute time and space with spacetime and allowed an accurate description of systems whose components have speeds approaching the speed of light. Max Planck, Erwin Schrödinger, and others introduced quantum mechanics, a probabilistic notion of particles and interactions that allowed an accurate description of atomic and subatomic scales. Later, quantum field theory unified quantum mechanics and special relativity. General relativity allowed for a dynamical, curved spacetime, with which highly massive systems and the large-scale structure of the universe can be well-described. General relativity has not yet been unified with the other fundamental descriptions; several candidate theories of quantum gravity are being developed.
Related portals
Good articles -
These are Good articles, which meet a core set of high editorial standards.
-
DU Spectrophotometer, National Technical Laboratories, 1947
The DU spectrophotometer or Beckman DU, introduced in 1941, was the first commercially viable scientific instrument for measuring the amount of ultraviolet light absorbed by a substance. This model of spectrophotometer enabled scientists to easily examine and identify a given substance based on its absorption spectrum, the pattern of light absorbed at different wavelengths. Arnold O. Beckman's National Technical Laboratories (later Beckman Instruments) developed three in-house prototype models (A, B, C) and one limited distribution model (D) before moving to full commercial production with the DU. Approximately 30,000 DU spectrophotometers were manufactured and sold between 1941 and 1976.
Sometimes referred to as a UV–Vis spectrophotometer because it measured both the ultraviolet (UV) and visible spectra, the DU spectrophotometer is credited as being a truly revolutionary technology. It yielded more accurate results than previous methods for determining the chemical composition of a complex substance, and substantially reduced the time needed for an accurate analysis from weeks or hours to minutes. The Beckman DU was essential to several critical secret research projects during World War II, including the development of penicillin and synthetic rubber. (Full article...) -
A black hole is a region of spacetime wherein gravity is so strong that no matter or electromagnetic energy (e.g. light) can escape it. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of no escape is called the event horizon. A black hole has a great effect on the fate and circumstances of an object crossing it, but it has no locally detectable features according to general relativity. In many ways, a black hole acts like an ideal black body, as it reflects no light. Quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is of the order of billionths of a kelvin for stellar black holes, making it essentially impossible to observe directly.
Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. In 1916, Karl Schwarzschild found the first modern solution of general relativity that would characterise a black hole. Due to his influential research, the Schwarzschild metric is named after him. David Finkelstein, in 1958, first published the interpretation of "black hole" as a region of space from which nothing can escape. Black holes were long considered a mathematical curiosity; it was not until the 1960s that theoretical work showed they were a generic prediction of general relativity. The discovery of neutron stars by Jocelyn Bell Burnell in 1967 sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality. The first black hole known was Cygnus X-1, identified by several researchers independently in 1971. (Full article...) -
Walter Henry Zinn (December 10, 1906 – February 14, 2000) was a Canadian-born American nuclear physicist who was the first director of the Argonne National Laboratory from 1946 to 1956. He worked at the Manhattan Project's Metallurgical Laboratory during World War II, and supervised the construction of Chicago Pile-1, the world's first nuclear reactor, which went critical on December 2, 1942, at the University of Chicago. At Argonne he designed and built several new reactors, including Experimental Breeder Reactor I, the first nuclear reactor to electrically power a building, which went live on December 20, 1951. (Full article...) -
George Thomas Reynolds (May 27, 1917 – April 19, 2005) was an American physicist best known for his accomplishments in particle physics, biophysics and environmental science.
Reynolds received his PhD in physics from Princeton in 1943, writing a thesis of the propagation of shock waves. During World War II, he joined the United States Navy, and served with the Manhattan Project. He worked with George Kistiakowsky on the design of the explosive lenses required by the implosion-type nuclear weapon. He was involved in the investigation of the Port Chicago disaster, served with Project Alberta on Tinian, and was part of the Manhattan Project team sent to Hiroshima and Nagasaki to inspect the bomb damage. (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...) -
Luis Walter Alvarez (June 13, 1911 – September 1, 1988) was an American experimental physicist, inventor, and professor 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...) -
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...) -
Margaret Eliza Maltby (December 10, 1860 – May 3, 1944) was an American physicist notable for her measurement of high electrolytic resistances and the conductivity of very dilute solutions. Maltby was the first woman to earn a Bachelor of Science degree from the Massachusetts Institute of Technology, and the first woman to earn a Ph.D. in physics from any German university.
She taught for over 30 years at Barnard College where she introduced one of the first courses on the physics of music. Maltby was active in the American Association of University Women where she was instrumental in helping female academics receive fellowships to study and conduct research, at a time when it was uncommon for women to be eligible for such fellowships. (Full article...) -
Maria Salomea Skłodowska-Curie (Polish: [ˈmarja salɔˈmɛa skwɔˈdɔfska kʲiˈri] ⓘ; née Skłodowska; 7 November 1867 – 4 July 1934), known simply 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.
She was born in Warsaw, in what was then the Kingdom of Poland, part of the Russian Empire. She studied at Warsaw's clandestine Flying University and began her practical scientific training in Warsaw. In 1891, aged 24, she followed her elder sister Bronisława to study in Paris, where she earned her higher degrees and conducted her subsequent scientific work. In 1895, she married the French physicist Pierre Curie, and she shared the 1903 Nobel Prize in Physics with him and with the physicist Henri Becquerel for their pioneering work developing the theory of "radioactivity"—a term she coined. In 1906, Pierre Curie died in a Paris street accident. Marie won the 1911 Nobel Prize in Chemistry for her discovery of the elements polonium and radium, using techniques she invented for isolating radioactive isotopes. Under her direction, the world's first studies were conducted into the treatment of neoplasms by the use of radioactive isotopes. She founded the Curie Institute in Paris in 1920, and the Curie Institute in Warsaw in 1932; both remain major medical research centres. During World War I, she developed mobile radiography units to provide X-ray services to field hospitals. (Full article...) -
In a nuclear weapon, a tamper is an optional layer of dense material surrounding the fissile material. It is used in nuclear weapon design to reduce the critical mass and to delay the expansion of the reacting material through its inertia, which delays the thermal expansion of the fissioning fuel mass, keeping it supercritical longer. Often the same layer serves both as tamper and as neutron reflector. The weapon disintegrates as the reaction proceeds, and this stops the reaction, so the use of a tamper makes for a longer-lasting, more energetic and more efficient explosion. The yield can be further enhanced using a fissionable tamper.
The first nuclear weapons used heavy natural uranium or tungsten carbide tampers, but a heavy tamper necessitates a larger high-explosive implosion system and makes the entire device larger and heavier. The primary stage of a modern thermonuclear weapon may instead use a lightweight beryllium reflector, which is also transparent to X-rays when ionized, allowing the primary's energy output to escape quickly to be used in compressing the secondary stage. More exotic tamper materials such as gold are used for special purposes like emitting large amounts of X-rays or altering the amount of nuclear fallout. (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...) -
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...) -
Noctilucent clouds (NLCs), or night shining clouds, are tenuous cloud-like phenomena in the upper atmosphere of Earth. When viewed from space, they are called polar mesospheric clouds (PMCs), detectable as a diffuse scattering layer of water ice crystals near the summer polar mesopause. They consist of ice crystals and from the ground are only visible during astronomical twilight. Noctilucent roughly means "night shining" in Latin. They are most often observed during the summer months from latitudes between ±50° and ±70°. Too faint to be seen in daylight, they are visible only when the observer and the lower layers of the atmosphere are in Earth's shadow, but while these very high clouds are still in sunlight. Recent studies suggest that increased atmospheric methane emissions produce additional water vapor through chemical reactions once the methane molecules reach the mesosphere – creating, or reinforcing existing, noctilucent clouds.
They are the highest clouds in Earth's atmosphere, located in the mesosphere at altitudes of around 76 to 85 km (249,000 to 279,000 ft). (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...)
-
Wu Zhonghua (Chinese: 吴仲华; 27 July 1917 – 19 September 1992), also known as Chung-Hua Wu, was a Chinese physicist. He was a National Advisory Committee for Aeronautics (NACA) researcher, Tsinghua University professor, and Founding Director of the Institute of Engineering Thermophysics of the Chinese Academy of Sciences (CAS). He pioneered the general theory of three-dimensional flow for turbomachinery, which has been widely used in aircraft engine designs. Wu and his wife Li Minhua were both academicians of the CAS.
Born in Shanghai, Wu's college education at Tsinghua University was interrupted by the Second Sino-Japanese War. He graduated from the temporary National Southwestern Associated University and was awarded a Boxer Indemnity Scholarship to study at the Massachusetts Institute of Technology in the United States. After earning his Ph.D., he joined the NACA, the predecessor of NASA, where he developed the theory of three-dimensional flow. (Full article...)
December anniversaries
- 1610 – Galileo Galilei observes phases of Venus.
- 1900 - The peer reviewed journal "Nature" reports on Duddell's "Singing Arc" American Physical Society.
- 1942 - First self-sustained nuclear chain reaction at the University of Chicago under the supervision of Enrico Fermi. American Physical Society
- 1968 – Apollo 8 Launched
- 1995 – Hubble Deep Field images taken.
Births
- 1852 - Henri Becquerel
- 1900 - George Eugene Uhlenbeck
- 25 December, 1642 - Isaac Newton
- 5 December, 1901 - Werner Heisenberg
- 18 December, 1856 - J. J. Thomson
General images
The following are images from various physics-related articles on Wikipedia.
-
The quantum Hall effect: Components of the Hall resistivity as a function of the external magnetic field (from Condensed matter 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) -
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) -
Gottfried Leibniz (1646–1716) (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) -
Sir Isaac Newton (1642–1727) (from History of 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) -
The Polish astronomer Nicolaus Copernicus (1473–1543) is remembered for his development of a heliocentric model of the Solar System. (from History of physics) -
Marie Skłodowska-Curie
(1867–1934) was awarded two Nobel prizes, Physics (1903) and Chemistry (1911) (from History of physics) -
Johannes Kepler.(1571–1630) (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) -
Christiaan Huygens (1629–1695) (from History of physics) -
A composite montage comparing Jupiter (lefthand side) and its four Galilean moons (top to bottom: Io, Europa, Ganymede, Callisto) (from History of physics) -
Max Planck (1858–1947) (from History of physics) -
James Clerk Maxwell (1831–1879) (from History of physics) -
Heike Kamerlingh Onnes and Johannes van der Waals with the helium liquefactor at Leiden in 1908 (from Condensed matter physics) -
Werner Heisenberg (1901–1976) (from History of physics) -
The ancient Greek mathematician Archimedes, developer of ideas regarding fluid mechanics and buoyancy. (from History of physics) -
The Standard Model (from History of physics) -
Ludwig Boltzmann (1844–1906) (from History of physics) -
William Thomson (Lord Kelvin)
(1824–1907) (from History of physics) -
-
Alessandro Volta (1745–1827) (from History of physics) -
Michael Faraday (1791–1867) (from History of physics) -
Image of X-ray diffraction pattern from a protein crystal (from Condensed matter 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) -
Albert Einstein (1879–1955), photographed here in around 1905 (from History of physics) -
Daniel Bernoulli (1700–1782) (from History of physics) -
René Descartes (1596–1650) (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) -
-
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) -
-
-
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) -
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) -
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)
-Portrait-Portr_10971.tif_(cropped).jpg)
_in_1958.jpg)
Categories
Fundamentals: Concepts in physics | Constants | Physical quantities | Units of measure | Mass | Length | Time | Space | Energy | Matter | Force | Gravity | Electricity | Magnetism | Waves
Basic physics: Mechanics | Electromagnetism | Statistical mechanics | Thermodynamics | Quantum mechanics | Theory of relativity | Optics | Acoustics
Specific fields: Acoustics | Astrophysics | Atomic physics | Molecular physics | Optical physics | Computational physics | Condensed matter physics | Nuclear physics | Particle physics | Plasma physics
Tools: Detectors | Interferometry | Measurement | Radiometry | Spectroscopy | Transducers
Background: Physicists | History of physics | Philosophy of physics | Physics education | Physics journals | Physics organizations
Other: Physics in fiction | Physics lists | Physics software | Physics stubs
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.
More recognized content
Associated Wikimedia
The following Wikimedia Foundation sister projects provide more on this subject:
-
Commons
Free media repository -
Wikibooks
Free textbooks and manuals -
Wikidata
Free knowledge base -
Wikinews
Free-content news -
Wikiquote
Collection of quotations -
Wikisource
Free-content library -
Wikiversity
Free learning tools -
Wikivoyage
Free travel guide -
Wiktionary
Dictionary and thesaurus
