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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. 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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This is a Featured article, which represents some of the best content on English Wikipedia.
A star is a luminous spheroid of plasma held together by self-gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night; their immense distances from Earth make them appear as fixed points of light. The most prominent stars have been categorised into constellations and asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated 1022 to 1024 stars. Only about 4,000 of these stars are visible to the naked eye—all within the Milky Way galaxy.
A star's life begins with the gravitational collapse of a gaseous nebula of material largely comprising hydrogen, helium, and trace heavier elements. Its total mass mainly determines its evolution and eventual fate. A star shines for most of its active life due to the thermonuclear fusion of hydrogen into helium in its core. This process releases energy that traverses the star's interior and radiates into outer space. At the end of a star's lifetime as a fusor, its core becomes a stellar remnant: a white dwarf, a neutron star, or—if it is sufficiently massive—a black hole. (Full article...)
Did you know -
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- ...that while Albert Einstein is most famous for his Theory of Relativity, he was awarded the Nobel Prize for his explanation of the photoelectric effect?
- ...that gravitational tidal accelerations are the result of the curvature of spacetime?
- ...that the blue glow of the Cherenkov effect is due to electrons moving faster than the speed of light in water?
Selected image -
The heliospheric current sheet extends to the outer reaches of the Solar System, and results from the influence of the Sun's rotating magnetic field on the plasma in the interplanetary medium.
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Good articles -
These are Good articles, which meet a core set of high editorial standards.
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Lightning (pictured) and urban lighting are some of the most dramatic effects of electricity
Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others.
The presence of either a positive or negative electric charge produces an electric field. The motion of electric charges is an electric current and produces a magnetic field. In most applications, Coulomb's law determines the force acting on an electric charge. Electric potential is the work done to move an electric charge from one point to another within an electric field, typically measured in volts. (Full article...) -
A gravity bong, also known as a GB, bucket bong, grav, geeb, gibby, yoin, or ghetto bong, is a method of consuming smokable substances such as cannabis. The term describes both a bucket bong and a waterfall bong, since both use air pressure and water to draw smoke. A lung uses similar equipment but instead of water draws the smoke by removing a compacted plastic bag or similar from the chamber.
The bucket bong is made out of two containers, with the larger, open top container filled with water. The smaller has an attached bowl and open bottom, and the smaller is placed into the larger. Once the bowl is lit, the operator must move the small container up, causing a pressure difference. Smoke slowly fills the small jar until the user removes the bowl and inhales the contents. A waterfall bong is made up of only one container. The container must have a bowl and a small hole near the base so the water can drain easily. As the water flows out of the container, air is forced through the bowl and causes the substance to burn and accumulate smoke in the bong. (Full article...) -
Sir Edmund Taylor Whittaker FRS FRSE (24 October 1873 – 24 March 1956) was a British mathematician, physicist, and historian of science. Whittaker was a leading mathematical scholar of the early 20th century who contributed widely to applied mathematics and was renowned for his research in mathematical physics and numerical analysis, including the theory of special functions, along with his contributions to astronomy, celestial mechanics, the history of physics, and digital signal processing.
Among the most influential publications in Whittaker's bibliography, he authored several popular reference works in mathematics, physics, and the history of science, including A Course of Modern Analysis (better known as Whittaker and Watson), Analytical Dynamics of Particles and Rigid Bodies, and A History of the Theories of Aether and Electricity. Whittaker is also remembered for his role in the relativity priority dispute, as he credited Henri Poincaré and Hendrik Lorentz with developing special relativity in the second volume of his History, a dispute which has lasted several decades, though scientific consensus has remained with Einstein. Whittaker served as the Royal Astronomer of Ireland early in his career, a position he held from 1906 through 1912, before moving on to the chair of mathematics at the University of Edinburgh for the next three decades and, towards the end of his career, received the Copley Medal and was knighted. The School of Mathematics of the University of Edinburgh holds The Whittaker Colloquium, a yearly lecture, in his honour and the Edinburgh Mathematical Society promotes an outstanding young Scottish mathematician once every four years with the Sir Edmund Whittaker Memorial Prize, also given in his honour. (Full article...) -
Bruno Benedetto Rossi (/ˈrɒsi/ ROSS-ee, Italian: [ˈbruːno beneˈdetto ˈrossi]; 13 April 1905 – 21 November 1993) was an Italian-American experimental physicist. He made major contributions to particle physics and the study of cosmic rays. A 1927 graduate of the University of Bologna, he became interested in cosmic rays. To study them, he invented an improved electronic coincidence circuit, and travelled to Eritrea to conduct experiments that showed that cosmic ray intensity from the West was significantly larger than that from the East.
Forced to emigrate in October 1938 due to the Italian racial laws, Rossi moved to Denmark, where he worked with Niels Bohr. He then moved to Britain, where he worked with Patrick Blackett at the University of Manchester. Finally he went to the United States, where he worked with Enrico Fermi at the University of Chicago, and later at Cornell University. Rossi stayed in the United States, and became an American citizen. (Full article...) -
Norris Edwin Bradbury (May 30, 1909 – August 20, 1997), was an American physicist who served as director of the Los Alamos National Laboratory for 25 years from 1945 to 1970. He succeeded Robert Oppenheimer, who personally chose Bradbury for the position of director after working closely with him on the Manhattan Project during World War II. Bradbury was in charge of the final assembly of "the Gadget", detonated in July 1945 for the Trinity test.
Bradbury took charge at Los Alamos at a difficult time. Staff were leaving in droves, living conditions were poor and there was a possibility that the laboratory would close. He managed to persuade enough staff to stay and got the University of California to renew the contract to manage the laboratory. He pushed continued development of nuclear weapons, transforming them from laboratory devices to production models. Numerous improvements made them safer, more reliable and easier to store and handle, and made more efficient use of scarce fissionable materiel. (Full article...) -
Alvin Cushman Graves (November 4, 1909 – July 28, 1965) was an American nuclear physicist who served at the Manhattan Project's Metallurgical Laboratory and the Los Alamos Laboratory during World War II. After the war, he became the head of the J (Test) Division at Los Alamos and was director or assistant director of numerous nuclear weapons tests during the 1940s and 1950s. Graves was severely injured in the 1946 laboratory criticality accident in Los Alamos that killed Louis Slotin, but recovered. (Full article...) -
The Type Ib supernova SN 2008D in galaxy NGC 2770, shown in X-ray (left) and visible light (right), at the corresponding positions of the images. (NASA image.)
Type Ib and Type Ic supernovae are categories of supernovae that are caused by the stellar core collapse of massive stars. These stars have shed or been stripped of their outer envelope of hydrogen, and, when compared to the spectrum of Type Ia supernovae, they lack the absorption line of silicon. Compared to Type Ib, Type Ic supernovae are hypothesized to have lost more of their initial envelope, including most of their helium. The two types are usually referred to as stripped core-collapse supernovae. (Full article...) -
Sir Harrie Stewart Wilson Massey FRS (16 May 1908 – 27 November 1983) was an Australian mathematical physicist who worked primarily in the fields of atomic and atmospheric physics.
A graduate of the University of Melbourne and Cambridge University, where he earned his doctorate at the Cavendish Laboratory, Massey became an independent lecturer in Mathematical Physics at the Queen's University of Belfast in 1933. He was appointed Goldsmid Professor of Applied Mathematics at University College London, in 1938. During the Second World War, Massey worked at the Admiralty Research Laboratory, where he helped devise countermeasures for German magnetic naval mines, and at the Admiralty Mining Establishment in Havant, where he helped develop British naval mines. In 1943, Mark Oliphant persuaded the Admiralty to release Massey to work on the Manhattan Project. He joined Oliphant's British Mission at the Radiation Laboratory at the University of California, where they worked on the electromagnetic isotope separation process. When Oliphant returned to Britain in 1945, Massey took over the Berkeley Mission. (Full article...) -
Units in everyday use by country as of 2019
The history of the metric system began during the Age of Enlightenment with measures of length and weight derived from nature, along with their decimal multiples and fractions. The system became the standard of France and Europe within half a century. Other measures with unity ratios were added, and the system went on to be adopted across the world.
The first practical realisation of the metric system came in 1799, during the French Revolution, after the existing system of measures had become impractical for trade, and was replaced by a decimal system based on the kilogram and the metre. The basic units were taken from the natural world. The unit of length, the metre, was based on the dimensions of the Earth, and the unit of mass, the kilogram, was based on the mass of a volume of water of one litre (a cubic decimetre). Reference copies for both units were manufactured in platinum and remained the standards of measure for the next 90 years. After a period of reversion to the mesures usuelles due to unpopularity of the metric system, the metrication of France and much of Europe was complete by the 1850s. (Full article...) -
Matteucci's frog battery, 1845 (top left); Aldini's frog battery, 1818 (bottom); apparatus for controlled exposure of gases to frog battery (top right).
A frog battery is an electrochemical battery consisting of a number of dead frogs (or sometimes live ones), which form the cells of the battery connected in a series arrangement. It is a kind of biobattery. It was used in early scientific investigations of electricity and academic demonstrations.
The principle behind the battery is the injury potential created in a muscle when it is damaged, although this was not fully understood in the 18th and 19th centuries; the potential being caused incidentally due to the dissection of the frog's muscles. (Full article...) -
John Clive Ward, FRS (1 August 1924 – 6 May 2000) was an Anglo-Australian physicist who made significant contributions to quantum field theory, condensed-matter physics, and statistical mechanics. Andrei Sakharov called Ward one of the titans of quantum electrodynamics.
Ward introduced the Ward–Takahashi identity. He was one of the authors of the Standard Model of gauge particle interactions: his contributions were published in a series of papers he co-authored with Abdus Salam. He is also credited with being an early advocate of the use of Feynman diagrams. It has been said that physicists have made use of his principles and developments "often without knowing it, and generally without quoting him." The Ising model was another one of his research interests. (Full article...) -
Electrical elastance is the reciprocal of capacitance. The SI unit of elastance is the inverse farad (F−1). The concept is not widely used by electrical and electronic engineers, as the value of capacitors is typically specified in units of capacitance rather than inverse capacitance. However, elastance is used in theoretical work in network analysis and has some niche applications, particularly at microwave frequencies.
The term elastance was coined by Oliver Heaviside through the analogy of a capacitor to a spring. The term is also used for analogous quantities in other energy domains. In the mechanical domain, it corresponds to stiffness, and it is the inverse of compliance in the fluid flow domain, especially in physiology. It is also the name of the generalized quantity in bond-graph analysis and other schemes that analyze systems across multiple domains. (Full article...) -
Flash X-Ray images of the converging shock waves formed during a test of the high explosive lens system.
The RaLa Experiment, or RaLa, was a series of tests during and after the Manhattan Project designed to study the behavior of converging shock waves to achieve the spherical implosion necessary for compression of the plutonium pit of the nuclear weapon. The experiment used significant amounts of a short-lived radioisotope lanthanum-140, a potent source of gamma radiation; the RaLa is a contraction of Radioactive Lanthanum. The method was proposed by Robert Serber and developed by a team led by the Italian experimental physicist Bruno Rossi.
The tests were performed with 1⁄8 inch (3.2 mm) spheres of radioactive lanthanum, equal to about 100 curies (3.7 TBq) and later 1,000 Ci (37 TBq), located in the center of a simulated nuclear device. The explosive lenses were designed primarily using this series of tests. Some 254 tests were conducted between September 1944 and March 1962. In his history of the Los Alamos project, David Hawkins wrote: “RaLa became the most important single experiment affecting the final bomb design”. (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...) -
Sir Chandrasekhara Venkata Raman FRS (/ˈrɑːmən/; 7 November 1888 – 21 November 1970), known as C. V. Raman, was an Indian physicist known for his work in the field of light scattering. Using a spectrograph that he developed, he and his student K. S. Krishnan discovered that when light traverses a transparent material, the deflected light changes its wavelength. This phenomenon, a hitherto unknown type of scattering of light, which they called "modified scattering" was subsequently termed the Raman effect or Raman scattering. Raman received the 1930 Nobel Prize in Physics for the discovery and was the first Asian and the first non-White to receive a Nobel Prize in any branch of science.
Born to Tamil Brahmin parents, Raman was a precocious child, completing his secondary and higher secondary education from St Aloysius' Anglo-Indian High School at the age of 11 and 13, respectively. He topped the bachelor's degree examination of the University of Madras with honours in physics from Presidency College at age 16. His first research paper, on diffraction of light, was published in 1906 while he was still a graduate student. The next year he obtained a master's degree. He joined the Indian Finance Service in Calcutta as Assistant Accountant General at age 19. There he became acquainted with the Indian Association for the Cultivation of Science (IACS), the first research institute in India, which allowed him to carry out independent research and where he made his major contributions in acoustics and optics. (Full article...)
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November anniversaries
- 1952 - detonation of the first Hydrogen bomb, code named "Ivy Mike".
- 1947 - invention of the first transistor, between November 17 to December 23. APS.
- 1930 - Patent granted for Einstein-Szilard refrigerator designed by Albert Einstein and Leó Szilárd. APS.
- 1919 - Elmer Imes's published work presented the first accurate measurement of the distance between atoms in molecules with high resolution infrared spectroscopy. APS.
- 1915 – Einstein's presentation to the Prussian Academy of Science specifies how the geometry of space and time is influenced by whatever matter is present. (see: General relativity and APS)
- 1895 - Wilhelm Conrad Roentgen discovers X-rays.
- 1887 - Michelson–Morley experiment provided strong evidence against the luminiferous ether. APS.
- 1872 - death of Mary Somerville who gained an international reputation as a scientist in the intervals of raising a family of six children. APS
- 1783 - John Michell predicted the existence of black holes, and the possibility of a luminous twin to aid in detection. APS
- 1676 – using his first quantitative measurement of the speed of light, Ole Rømer accurately predicts the delay of eclipse of Io
Births
- 1934 – Carl Sagan
- 1932 - Melvin Schwartz
- 1929 - Richard E. Taylor
- 1925 - Simon van der Meer
- 1902 - Eugene Wigner
- 1837 - Johannes Diderik van der Waals
- 1867 - Marie Curie (Nov. 7)
- 1828 - Balfour Stewart
- 1878 - Lise Meitner (Nov. 7)
- 1887 - Henry Moseley
- 1888 - C V Raman (Nov. 7)
- 1892 - Dmitri Skobeltsyn (Nov. 24)
General images
The following are images from various physics-related articles on Wikipedia.
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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) -
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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) -
Galileo Galilei, early proponent of the modern scientific worldview and method
(1564–1642) (from History of physics) -
William Thomson (Lord Kelvin)
(1824–1907) (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) -
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Image of X-ray diffraction pattern from a protein crystal (from Condensed matter 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) -
The Standard Model (from History of physics) -
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The ancient Greek mathematician Archimedes, developer of ideas regarding fluid mechanics and buoyancy. (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) -
The quantum Hall effect: Components of the Hall resistivity as a function of the external magnetic field (from Condensed matter 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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Albert Einstein (1879–1955), photographed here in around 1905 (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) -
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) -
Chien-Shiung Wu worked on parity violation in 1956 and announced her results in January 1957. (from History of physics) -
Marie Skłodowska-Curie
(1867–1934) She was awarded two Nobel prizes, Physics (1903) and Chemistry (1911) (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) -
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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) -
Christiaan Huygens
(1629–1695) (from History of physics) -
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Richard Feynman's Los Alamos ID badge (from History of physics) -
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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) -
Sir Isaac Newton
(1642–1727) (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) -
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) -
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 cylindrical equirectangular projection. (from History of physics) -
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Categories
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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.
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