Physics is one of the oldest
academic disciplines and, through its inclusion of
astronomy, perhaps the oldest. 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 emerged as unique research endeavors in their own right. 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.
These are
Good articles, which meet a core set of high editorial standards.
Image 1
Figure 1. Apparatus used in the Fizeau experiment The Fizeau experiment was carried out by
Hippolyte Fizeau in 1851 to measure the relative speeds of light in moving water. Fizeau used a special
interferometer arrangement to measure the effect of movement of a medium upon the speed of light.
According to the theories prevailing at the time, light traveling through a moving medium would be dragged along by the medium, so that the measured speed of the light would be a simple sum of its speed through the medium plus the speed of the medium. Fizeau indeed detected a dragging effect, but the magnitude of the effect that he observed was far lower than expected. When he repeated the experiment with air in place of water he observed no effect. His results seemingly supported the
partial aether-drag hypothesis of
Fresnel, a situation that was disconcerting to most physicists. Over half a century passed before a satisfactory explanation of Fizeau's unexpected measurement was developed with the advent of
Albert Einstein's theory of
special relativity. Einstein later pointed out the importance of the experiment for special relativity, in which it corresponds to the relativistic
velocity-addition formula when restricted to small velocities. (Full article...)
c. 1680Portrait of a Mathematician by
Mary Beale, conjectured to be of Hooke but also conjectured to be of
Isaac Barrow
Robert HookeFRS (/hʊk/; 18 July 1635 – 3 March 1703) was an English
polymath who was active as a physicist ("natural philosopher"), astronomer, geologist, meteorologist and architect. He is credited as one of the first scientists to investigate living things at
microscopic scale in 1665, using a
compound microscope that he designed. Hooke was an impoverished scientific inquirer in young adulthood who went on to became one of the most important scientists of his time. After the
Great Fire of London in 1666, Hooke (as a surveyor and architect) attained wealth and esteem by performing more than half of the
property line surveys and assisting with the city's rapid reconstruction. Often vilified by writers in the centuries after his death, his reputation was restored at the end of the twentieth century and he has been called "England's
Leonardo [da Vinci]".
Hooke was a
Fellow of the Royal Society and from 1662, he was its first Curator of Experiments. From 1665 to 1703, he was also
Professor of Geometry at Gresham College. Hooke began his scientific career as an assistant to the physical scientist
Robert Boyle. Hooke built the
vacuum pumps that were used in Boyle's experiments on
gas law and also conducted experiments. In 1664, Hooke identified the rotations of
Mars and
Jupiter. Hooke's 1665 book Micrographia, in which he coined the term cell, encouraged microscopic investigations. Investigating
optics – specifically light
refraction – Hooke inferred a
wave theory of light. His is the first-recorded hypothesis of the cause of the expansion of matter by heat, of air's composition by small particles in constant motion that thus generate its pressure, and of heat as energy. (Full article...)
A graduate of the
University of Göttingen, Goeppert Mayer wrote her doctoral thesis on the theory of possible
two-photon absorption by atoms. At the time, the chances of experimentally verifying her thesis seemed remote, but the development of the
laser in the 1960s later permitted this. Today, the unit for the two-photon
absorption cross section is named the Goeppert Mayer (GM) unit. (Full article...)
Image 6
Val Logsdon Fitch (March 10, 1923 – February 5, 2015) was an American
nuclear physicist who, with co-researcher
James Cronin, was awarded the 1980
Nobel Prize in Physics for a 1964 experiment using the
Alternating Gradient Synchrotron at
Brookhaven National Laboratory that proved that certain
subatomic reactions do not adhere to fundamental symmetry principles. Specifically, they proved, by examining the decay of
K-mesons, that a reaction run in reverse does not retrace the path of the original reaction, which showed that the reactions of subatomic particles are not indifferent to time. Thus the phenomenon of
CP violation was discovered. This demolished the faith that physicists had that natural laws were governed by symmetry.
The expanding remnant of
SN 1987A, a peculiar Type II supernova in the
Large Magellanic Cloud. NASA image. A Type II supernova or SNII (plural: supernovae) results from the rapid collapse and violent explosion of a massive
star. A star must have at least eight times, but no more than 40 to 50 times, the
mass of the Sun (
M☉) to undergo this type of explosion. Type II supernovae are distinguished from other types of
supernovae by the presence of hydrogen in their
spectra. They are usually observed in the
spiral arms of
galaxies and in
H II regions, but not in
elliptical galaxies; those are generally composed of older, low-mass stars, with few of the young, very massive stars necessary to cause a supernova.
Stars generate energy by the
nuclear fusion of elements. Unlike the Sun, massive stars possess the mass needed to fuse elements that have an
atomic mass greater than hydrogen and helium, albeit at increasingly higher
temperatures and
pressures, causing correspondingly shorter stellar life spans. The
degeneracy pressure of electrons and the energy generated by these
fusion reactions are sufficient to counter the force of gravity and prevent the star from collapsing, maintaining stellar equilibrium. The star fuses increasingly higher mass elements, starting with
hydrogen and then
helium, progressing up through the periodic table until a core of
iron and
nickel is produced. Fusion of iron or nickel produces no net energy output, so no further fusion can take place, leaving the nickel–iron core inert. Due to the lack of energy output creating outward thermal pressure, the core contracts due to gravity until the overlying weight of the star can be supported largely by electron degeneracy pressure. (Full article...)
An
Andrea Amati violin, which may have been made as early as 1558, making it one of the earliest violins in existence Violin acoustics is an area of study within
musical acoustics concerned with how the sound of a
violin is created as the result of interactions between
its many parts. These acoustic qualities are similar to those of other members of the
violin family, such as the
viola.
The energy of a
vibrating string is transmitted through the
bridge to the body of the violin, which allows the
sound to radiate into the surrounding air. Both ends of a violin
string are effectively stationary, allowing for the creation of
standing waves. A range of simultaneously produced
harmonics each affect the
timbre, but only the
fundamental frequency is heard. The frequency of a note can be raised by the increasing the string's
tension, or decreasing its length or
mass. The number of harmonics present in the tone can be reduced, for instance by the using the left hand to shorten the string length. The loudness and timbre of each of the strings is not the same, and the material used affects sound quality and ease of articulation. Violin strings were originally made from
catgut but are now usually made of steel or a synthetic material. Most strings are wound with metal to increase their mass while avoiding excess thickness. (Full article...)
A graduate of the
University of Marburg, which awarded him a doctorate in 1901, Hahn studied under Sir
William Ramsay at
University College London and at
McGill University in Montreal under
Ernest Rutherford, where he discovered several new radioactive isotopes. He returned to Germany in 1906;
Emil Fischer placed a former woodworking shop in the basement of the Chemical Institute at the
University of Berlin at his disposal to use as a laboratory. Hahn completed his
habilitation in the spring of 1907 and became a Privatdozent. In 1912, he became head of the Radioactivity Department of the newly founded
Kaiser Wilhelm Institute for Chemistry. Working with the Austrian physicist Lise Meitner in the building that now bears their names, he made a series of groundbreaking discoveries, culminating with her isolation of the longest-lived isotope of protactinium in 1918. (Full article...)
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...)
July 1914 –
AT&T tested the
first working transcontinental telephone line when the president of the company spoke from one coast to the other. Months later
Alexander Graham Bell repeated his famous statement over the phone in New York City which was heard by Dr. Watson in San Francisco.
Image 14The Hindu-Arabic numeral system. The inscriptions on the
edicts of Ashoka (3rd century BCE) display this number system being used by the Imperial
Mauryas. (from History of physics)
Image 22Computer 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)
Image 26One 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)
Image 36Classical 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)
This is a list of recognized content, updated weekly by
JL-Bot (
talk·contribs) (typically on Saturdays). There is no need to edit the list yourself. If an article is missing from the list, make sure it is
tagged (e.g. {{WikiProject Physics}}) or
categorized correctly and wait for the next update. See
WP:RECOG for configuration options.
Physics is one of the oldest
academic disciplines and, through its inclusion of
astronomy, perhaps the oldest. 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 emerged as unique research endeavors in their own right. 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.
These are
Good articles, which meet a core set of high editorial standards.
Image 1
Figure 1. Apparatus used in the Fizeau experiment The Fizeau experiment was carried out by
Hippolyte Fizeau in 1851 to measure the relative speeds of light in moving water. Fizeau used a special
interferometer arrangement to measure the effect of movement of a medium upon the speed of light.
According to the theories prevailing at the time, light traveling through a moving medium would be dragged along by the medium, so that the measured speed of the light would be a simple sum of its speed through the medium plus the speed of the medium. Fizeau indeed detected a dragging effect, but the magnitude of the effect that he observed was far lower than expected. When he repeated the experiment with air in place of water he observed no effect. His results seemingly supported the
partial aether-drag hypothesis of
Fresnel, a situation that was disconcerting to most physicists. Over half a century passed before a satisfactory explanation of Fizeau's unexpected measurement was developed with the advent of
Albert Einstein's theory of
special relativity. Einstein later pointed out the importance of the experiment for special relativity, in which it corresponds to the relativistic
velocity-addition formula when restricted to small velocities. (Full article...)
c. 1680Portrait of a Mathematician by
Mary Beale, conjectured to be of Hooke but also conjectured to be of
Isaac Barrow
Robert HookeFRS (/hʊk/; 18 July 1635 – 3 March 1703) was an English
polymath who was active as a physicist ("natural philosopher"), astronomer, geologist, meteorologist and architect. He is credited as one of the first scientists to investigate living things at
microscopic scale in 1665, using a
compound microscope that he designed. Hooke was an impoverished scientific inquirer in young adulthood who went on to became one of the most important scientists of his time. After the
Great Fire of London in 1666, Hooke (as a surveyor and architect) attained wealth and esteem by performing more than half of the
property line surveys and assisting with the city's rapid reconstruction. Often vilified by writers in the centuries after his death, his reputation was restored at the end of the twentieth century and he has been called "England's
Leonardo [da Vinci]".
Hooke was a
Fellow of the Royal Society and from 1662, he was its first Curator of Experiments. From 1665 to 1703, he was also
Professor of Geometry at Gresham College. Hooke began his scientific career as an assistant to the physical scientist
Robert Boyle. Hooke built the
vacuum pumps that were used in Boyle's experiments on
gas law and also conducted experiments. In 1664, Hooke identified the rotations of
Mars and
Jupiter. Hooke's 1665 book Micrographia, in which he coined the term cell, encouraged microscopic investigations. Investigating
optics – specifically light
refraction – Hooke inferred a
wave theory of light. His is the first-recorded hypothesis of the cause of the expansion of matter by heat, of air's composition by small particles in constant motion that thus generate its pressure, and of heat as energy. (Full article...)
A graduate of the
University of Göttingen, Goeppert Mayer wrote her doctoral thesis on the theory of possible
two-photon absorption by atoms. At the time, the chances of experimentally verifying her thesis seemed remote, but the development of the
laser in the 1960s later permitted this. Today, the unit for the two-photon
absorption cross section is named the Goeppert Mayer (GM) unit. (Full article...)
Image 6
Val Logsdon Fitch (March 10, 1923 – February 5, 2015) was an American
nuclear physicist who, with co-researcher
James Cronin, was awarded the 1980
Nobel Prize in Physics for a 1964 experiment using the
Alternating Gradient Synchrotron at
Brookhaven National Laboratory that proved that certain
subatomic reactions do not adhere to fundamental symmetry principles. Specifically, they proved, by examining the decay of
K-mesons, that a reaction run in reverse does not retrace the path of the original reaction, which showed that the reactions of subatomic particles are not indifferent to time. Thus the phenomenon of
CP violation was discovered. This demolished the faith that physicists had that natural laws were governed by symmetry.
The expanding remnant of
SN 1987A, a peculiar Type II supernova in the
Large Magellanic Cloud. NASA image. A Type II supernova or SNII (plural: supernovae) results from the rapid collapse and violent explosion of a massive
star. A star must have at least eight times, but no more than 40 to 50 times, the
mass of the Sun (
M☉) to undergo this type of explosion. Type II supernovae are distinguished from other types of
supernovae by the presence of hydrogen in their
spectra. They are usually observed in the
spiral arms of
galaxies and in
H II regions, but not in
elliptical galaxies; those are generally composed of older, low-mass stars, with few of the young, very massive stars necessary to cause a supernova.
Stars generate energy by the
nuclear fusion of elements. Unlike the Sun, massive stars possess the mass needed to fuse elements that have an
atomic mass greater than hydrogen and helium, albeit at increasingly higher
temperatures and
pressures, causing correspondingly shorter stellar life spans. The
degeneracy pressure of electrons and the energy generated by these
fusion reactions are sufficient to counter the force of gravity and prevent the star from collapsing, maintaining stellar equilibrium. The star fuses increasingly higher mass elements, starting with
hydrogen and then
helium, progressing up through the periodic table until a core of
iron and
nickel is produced. Fusion of iron or nickel produces no net energy output, so no further fusion can take place, leaving the nickel–iron core inert. Due to the lack of energy output creating outward thermal pressure, the core contracts due to gravity until the overlying weight of the star can be supported largely by electron degeneracy pressure. (Full article...)
An
Andrea Amati violin, which may have been made as early as 1558, making it one of the earliest violins in existence Violin acoustics is an area of study within
musical acoustics concerned with how the sound of a
violin is created as the result of interactions between
its many parts. These acoustic qualities are similar to those of other members of the
violin family, such as the
viola.
The energy of a
vibrating string is transmitted through the
bridge to the body of the violin, which allows the
sound to radiate into the surrounding air. Both ends of a violin
string are effectively stationary, allowing for the creation of
standing waves. A range of simultaneously produced
harmonics each affect the
timbre, but only the
fundamental frequency is heard. The frequency of a note can be raised by the increasing the string's
tension, or decreasing its length or
mass. The number of harmonics present in the tone can be reduced, for instance by the using the left hand to shorten the string length. The loudness and timbre of each of the strings is not the same, and the material used affects sound quality and ease of articulation. Violin strings were originally made from
catgut but are now usually made of steel or a synthetic material. Most strings are wound with metal to increase their mass while avoiding excess thickness. (Full article...)
A graduate of the
University of Marburg, which awarded him a doctorate in 1901, Hahn studied under Sir
William Ramsay at
University College London and at
McGill University in Montreal under
Ernest Rutherford, where he discovered several new radioactive isotopes. He returned to Germany in 1906;
Emil Fischer placed a former woodworking shop in the basement of the Chemical Institute at the
University of Berlin at his disposal to use as a laboratory. Hahn completed his
habilitation in the spring of 1907 and became a Privatdozent. In 1912, he became head of the Radioactivity Department of the newly founded
Kaiser Wilhelm Institute for Chemistry. Working with the Austrian physicist Lise Meitner in the building that now bears their names, he made a series of groundbreaking discoveries, culminating with her isolation of the longest-lived isotope of protactinium in 1918. (Full article...)
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...)
July 1914 –
AT&T tested the
first working transcontinental telephone line when the president of the company spoke from one coast to the other. Months later
Alexander Graham Bell repeated his famous statement over the phone in New York City which was heard by Dr. Watson in San Francisco.
Image 14The Hindu-Arabic numeral system. The inscriptions on the
edicts of Ashoka (3rd century BCE) display this number system being used by the Imperial
Mauryas. (from History of physics)
Image 22Computer 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)
Image 26One 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)
Image 36Classical 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)
This is a list of recognized content, updated weekly by
JL-Bot (
talk·contribs) (typically on Saturdays). There is no need to edit the list yourself. If an article is missing from the list, make sure it is
tagged (e.g. {{WikiProject Physics}}) or
categorized correctly and wait for the next update. See
WP:RECOG for configuration options.
Featured article - 
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Good articles - 
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)
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)
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)
The Standard Model (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)
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)
Galileo Galilei, early proponent of the modern scientific worldview and method
The ancient Greek mathematician Archimedes, developer of ideas regarding fluid mechanics and buoyancy. (from History of physics)
Albert Einstein (1879–1955), photographed here in around 1905 (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)
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)
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)
Heike Kamerlingh Onnes and Johannes van der Waals with the helium liquefactor at Leiden in 1908 (from Condensed matter physics)
Chien-Shiung Wu worked on parity violation in 1956 and announced her results in January 1957. (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)
Marie Skłodowska-Curie
William Thomson (Lord Kelvin)
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)
Richard Feynman's Los Alamos ID badge (from History of physics)
Sir Isaac Newton
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)
Christiaan Huygens
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 Polish astronomer Nicolaus Copernicus (1473–1543) is remembered for his development of a heliocentric model of the Solar System. (from History of physics)
Image of X-ray diffraction pattern from a protein crystal (from Condensed matter physics)
_in_1958.jpg)
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