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...)
Featured article -
This is a Featured article, which represents some of the best content on English Wikipedia.
Edward Teller (Hungarian: Teller Ede; January 15, 1908 – September 9, 2003) was a Hungarian and American theoretical physicist and chemical engineer who is known colloquially as "the father of the hydrogen bomb" and one of the creators of the Teller–Ulam design based on Stanisław Ulam's design.
Born in Austria-Hungary in 1908, Teller emigrated to the United States in the 1930s, one of the many so-called "Martians", a group of prominent Hungarian scientist émigrés. He made numerous contributions to nuclear and molecular physics, spectroscopy (in particular the Jahn–Teller and Renner–Teller effects), and surface physics. His extension of Enrico Fermi's theory of beta decay, in the form of Gamow–Teller transitions, provided an important stepping stone in its application, while the Jahn–Teller effect and the Brunauer–Emmett–Teller (BET) theory have retained their original formulation and are still mainstays in physics and chemistry. (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.
-
![Image 1 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...)](//upload.wikimedia.org/wikipedia/en/d/d2/Blank.png)
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 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...) -
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...) -
Figure 1: The Molniya orbit. Usually the period from perigee +2 hours to perigee +10 hours is used to transmit to the northern hemisphere.
A Molniya orbit (Russian: Молния, IPA: [ˈmolnʲɪjə] ⓘ, "Lightning") is a type of satellite orbit designed to provide communications and remote sensing coverage over high latitudes. It is a highly elliptical orbit with an inclination of 63.4 degrees, an argument of perigee of 270 degrees, and an orbital period of approximately half a sidereal day. The name comes from the Molniya satellites, a series of Soviet/Russian civilian and military communications satellites which have used this type of orbit since the mid-1960s. A variation on the Molniya orbit is the so-called Three Apogee (TAP) orbit, whose period is a third of a sidereal day.
The Molniya orbit has a long dwell time over the hemisphere of interest, while moving very quickly over the other. In practice, this places it over either Russia or Canada for the majority of its orbit, providing a high angle of view to communications and monitoring satellites covering these high-latitude areas. Geostationary orbits, which are necessarily inclined over the equator, can only view these regions from a low angle, hampering performance. In practice, a satellite in a Molniya orbit serves the same purpose for high latitudes as a geostationary satellite does for equatorial regions, except that multiple satellites are required for continuous coverage. (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...) -
Alvin Martin Weinberg (/ˈwaɪnbɜːrɡ/; April 20, 1915 – October 18, 2006) was an American nuclear physicist who was the administrator of Oak Ridge National Laboratory (ORNL) during and after the Manhattan Project. He came to Oak Ridge, Tennessee, in 1945 and remained there until his death in 2006. He was the first to use the term "Faustian bargain" to describe nuclear energy.
A graduate of the University of Chicago, which awarded him his doctorate in mathematical biophysics in 1939, Weinberg joined the Manhattan Project's Metallurgical Laboratory in September 1941. The following year he became part of Eugene Wigner's Theoretical Group, whose task was to design the nuclear reactors that would convert uranium into plutonium. (Full article...) -
As seen from the orbiting Earth, the Sun appears to move with respect to the fixed stars, and the ecliptic is the yearly path the Sun follows on the celestial sphere. This process repeats itself in a cycle lasting a little over 365 days.
The ecliptic or ecliptic plane is the orbital plane of Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making.
From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic against the background of stars – specifically the Zodiac constellations. The planets of the solar system can also be seen along the ecliptic, because their orbital planes are very close to Earth's. The moon's orbital plane is also similar to Earth's; the ecliptic is so named because the ancients noted that eclipses only occur when the Moon is crossing it. (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...) -
Incoming wave (red) reflected at the wall produces the outgoing wave (blue), both being overlaid resulting in the clapotis (black).
In hydrodynamics, a clapotis (from French for "lapping of water") is a non-breaking standing wave pattern, caused for example, by the reflection of a traveling surface wave train from a near vertical shoreline like a breakwater, seawall or steep cliff.
The resulting clapotic wave does not travel horizontally, but has a fixed pattern of nodes and antinodes.
These waves promote erosion at the toe of the wall, and can cause severe damage to shore structures. The term was coined in 1877 by French mathematician and physicist Joseph Valentin Boussinesq who called these waves 'le clapotis' meaning "the lapping".
In the idealized case of "full clapotis" where a purely monotonic incoming wave is completely reflected normal to a solid vertical wall,
the standing wave height is twice the height of the incoming waves at a distance of one half wavelength from the wall.
In this case, the circular orbits of the water particles in the deep-water wave are converted to purely linear motion, with vertical velocities at the antinodes, and horizontal velocities at the nodes. (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...) -
Robert Frederick Christy (May 14, 1916 – October 3, 2012) was a Canadian-American theoretical physicist and later astrophysicist who was one of the last surviving people to have worked on the Manhattan Project during World War II. He briefly served as acting president of California Institute of Technology (Caltech).
A graduate of the University of British Columbia (UBC) in the 1930s where he studied physics, he followed George Volkoff, who was a year ahead of him, to the University of California, Berkeley, where he was accepted as a graduate student by Robert Oppenheimer, the leading theoretical physicist in the United States at that time. Christy received his doctorate in 1941 and joined the physics department of Illinois Institute of Technology. (Full article...) -
Mary Jackson (née Winston; April 9, 1921 – February 11, 2005) was an American mathematician and aerospace engineer at the National Advisory Committee for Aeronautics (NACA), which in 1958 was succeeded by the National Aeronautics and Space Administration (NASA). She worked at Langley Research Center in Hampton, Virginia, for most of her career. She started as a computer at the segregated West Area Computing division in 1951. In 1958, after taking engineering classes, she became NASA's first black female engineer.
After 34 years at NASA, Jackson had earned the most senior engineering title available. She realized she could not earn further promotions without becoming a supervisor. She accepted a demotion to become a manager of both the Federal Women's Program, in the NASA Office of Equal Opportunity Programs and of the Affirmative Action Program. In this role, she worked to influence the hiring and promotion of women in NASA's science, engineering, and mathematics careers. (Full article...) -
Sir Joseph Rotblat KCMG CBE FRS (4 November 1908 – 31 August 2005) was a Polish and British physicist. During World War II he worked on Tube Alloys and the Manhattan Project, but left the Los Alamos Laboratory on grounds of conscience after it became clear to him in 1944 that Germany had ceased development of an atomic bomb.
His work on nuclear fallout was a major contribution toward the ratification of the 1963 Partial Nuclear Test Ban Treaty. A signatory of the 1955 Russell–Einstein Manifesto, he was secretary-general of the Pugwash Conferences on Science and World Affairs from their founding until 1973 and shared, with the Pugwash Conferences, the 1995 Nobel Peace Prize "for efforts to diminish the part played by nuclear arms in international affairs and, in the longer run, to eliminate such arms." (Full article...) -
Johann Carl Friedrich Gauss (German: Gauß [kaʁl ˈfʁiːdʁɪç ˈɡaʊs] ⓘ; Latin: Carolus Fridericus Gauss; 30 April 1777 – 23 February 1855) was a German mathematician, astronomer, geodesist, and physicist who contributed to many fields in mathematics and science. He was director of the Göttingen Observatory and professor of astronomy from 1807 until his death in 1855. He is widely considered one of the greatest mathematicians of all time.
While studying at the University of Göttingen, he propounded several mathematical theorems. Gauss completed his masterpieces Disquisitiones Arithmeticae and Theoria motus corporum coelestium as a private scholar. He gave the second and third complete proofs of the fundamental theorem of algebra, made contributions to number theory, and developed the theories of binary and ternary quadratic forms. (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...)
![Image 1 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...)](/wiki/File:Blank.png)
.jpg)
January anniversaries
1 January
- 1894 - Satyendra Nath Bose's birthday.
- 1801 - Giuseppe Piazzi is the first to notice the dwarf planet Ceres. However, very soon astronomers lose sight of its orbital path. After some months, Giuseppe Piazzi finally calculates its correct position on December 31.
- 1985 - Ernie Wise, a comedian, places the first mobile phone call in the UK.
2 January
- 2 January 1822 - Rudolf Clausius was born.
8 January
- 8 January 1942 - Stephen Hawking was born, on the same day that Galileo Galilei died in 1642.
15 January
- 15 January 1908 - Edward Teller was born.
General images
The following are images from various physics-related articles on Wikipedia.
-
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) -
-
Johannes Kepler.(1571–1630) (from History of physics) -
Marie Skłodowska-Curie
(1867–1934) was awarded two Nobel prizes, Physics (1903) and Chemistry (1911) (from History of physics) -
Michael Faraday (1791–1867) (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) -
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) -
The ancient Greek mathematician Archimedes, developer of ideas regarding fluid mechanics and buoyancy. (from History of physics) -
Rudolf Clausius (1822–1888) (from History of physics) -
-
Sir Isaac Newton (1642–1727) (from History of physics) -
-
-
Alessandro Volta (1745–1827) (from History of physics) -
Daniel Bernoulli (1700–1782) (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) -
Ludwig Boltzmann (1844–1906) (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) -
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) -
Werner Heisenberg (1901–1976) (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) -
René Descartes (1596–1650) (from History of physics) -
Richard Feynman's Los Alamos ID badge (from History of 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) -
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) -
William Thomson (Lord Kelvin)
(1824–1907) (from History of physics) -
Image of X-ray diffraction pattern from a protein crystal (from Condensed matter 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 Polish astronomer Nicolaus Copernicus (1473–1543) is remembered for his development of a heliocentric model of the Solar System. (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) -
Heike Kamerlingh Onnes and Johannes van der Waals with the helium liquefactor at Leiden in 1908 (from Condensed matter 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) -
Max Planck (1858–1947) (from History of physics) -
Gottfried Leibniz (1646–1716) (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) -
Albert Einstein (1879–1955), photographed here in around 1905 (from History of physics) -
Chien-Shiung Wu worked on parity violation in 1956 and announced her results in January 1957. (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) -
James Clerk Maxwell (1831–1879) (from History of physics) -
The Standard Model (from History of physics) -
Christiaan Huygens (1629–1695) (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
Sources
Portals on Wikipedia
