These are Good articles, which meet a core set of high editorial standards.
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Image 1Dr Adriana C. Ocampo Uria (born January 5, 1955) is a
Colombian -Argentinian planetary geologist and a former Science Program Manager at
NASA Headquarters. In 1970, Ocampo emigrated to California and completed her Bachelor in Science at California State University, Los Angeles, Master in Sciences at
California State University, Northridge and finished her PhD at the
Vrije Universiteit in the Netherlands. During high school and graduate studies she worked at the
Jet Propulsion Laboratory, where she served as the science coordinator for many planetary missions (Viking, Mars Observer, Voyager, Galileo
Galileo Mission, etc.).
She was the first to recognize, using
satellite images, that a ring of
cenotes or sinkholes, is the only surface impression of the buried
Chicxulub crater. This research contributed significantly to the understanding of this
impact crater. She later discover the most proximal ejecta blanket formation of the Chicxulub crater located in the border between Mexico and Belize. Ocampo has subsequently led at least seven research expeditions to the Chicxulub site. and to Belize K/Pg ejecta sites, which she discovered and were the subject of her MSc and PhD. She continues to search for new impact craters, and with her team, in 2017, reported on a possible crater near
Cali, Colombia. (
Full article...)
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Image 3Leo Szilard (;
Hungarian:
Leó Szilárd [ˈlɛoː ˈsilaːrd]; born
Leó Spitz; February 11, 1898 – May 30, 1964) was a Hungarian-born American physicist, biologist and inventor who made numerous important discoveries in nuclear physics and the biological sciences. He conceived the
nuclear chain reaction in 1933, and patented the idea in 1936. In late 1939 he wrote
the letter for
Albert Einstein's signature that resulted in the
Manhattan Project that built the
atomic bomb, and then in 1945 wrote the
Szilard petition asking president
Harry S. Truman to demonstrate the bomb without dropping it on civilians. According to
György Marx, he was one of the Hungarian scientists known as
The Martians.
Szilard initially attended
Palatine Joseph Technical University in
Budapest, but his engineering studies were interrupted by service in the
Austro-Hungarian Army during World War I. He left Hungary for Germany in 1919, enrolling at Technische Hochschule (Institute of Technology) in Berlin-Charlottenburg (now
Technische Universität Berlin), but became bored with engineering and transferred to
Friedrich Wilhelm University, where he studied physics. He wrote his doctoral thesis on
Maxwell's demon, a long-standing puzzle in the
philosophy of thermal and statistical physics. Szilard was the first scientist of note to recognize the connection between thermodynamics and
information theory. (
Full article...)
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Image 4The
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...)
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Image 5Insects are the only group of
invertebrates that have evolved
wings and
flight. Insects first flew in the
Carboniferous, some 300 to 350 million years ago, making them the first animals to evolve flight. Wings may have evolved from appendages on the sides of existing limbs, which already had nerves, joints, and muscles used for other purposes. These may initially have been used for sailing on water, or to slow the rate of descent when gliding.
One insect order,
Odonata, has flight muscles attached directly to the wings. In other winged insects, flight muscles attach to the thorax, which make it oscillate in order to induce the wings to beat. Of these insects, some (
flies and some
beetles) achieve very high wingbeat frequencies through the evolution of an "asynchronous" nervous system, in which the thorax oscillates faster than the rate of nerve impulses. (
Full article...)
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Image 6A
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...)
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Image 7In modern
cosmological theory,
diffusion damping, also called
photon diffusion damping, is a physical process which reduced density inequalities (
anisotropies) in the early
universe, making the universe itself and the
cosmic microwave background radiation (CMB) more uniform. Around 300,000 years after the
Big Bang, during the epoch of
recombination,
diffusing photons travelled from hot regions of space to cold ones, equalising the temperatures of these regions. This effect is responsible, along with
baryon acoustic oscillations, the
Doppler effect, and
the effects of gravity on electromagnetic radiation, for the eventual formation of
galaxies and
galaxy clusters, these being the dominant large scale structures which are observed in the universe. It is a damping
by diffusion, not
of diffusion.
The strength of diffusion damping is calculated by a mathematical expression for the
damping factor, which figures into the
Boltzmann equation, an equation which describes the amplitude of perturbations in the CMB. The strength of the diffusion damping is chiefly governed by the distance photons travel before being scattered (diffusion length). The primary effects on the diffusion length are from the properties of the plasma in question: different sorts of plasma may experience different sorts of diffusion damping. The evolution of a plasma may also affect the damping process. The scale on which diffusion damping works is called the
Silk scale and its value corresponds to the size of galaxies of the present day. The mass contained within the Silk scale is called the
Silk mass and it corresponds to the mass of the galaxies. (
Full article...)
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Image 8Mary Jackson (
née Winston; April 9, 1921 – February 11, 2005) was an
American 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...)
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Image 11A
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...)
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Image 12The
metric system is a
system of measurement that
standardises a set of base units and a
nomenclature for describing relatively large and small quantities via
decimal-based multiplicative
unit prefixes. Though the rules governing the metric system have changed over time, the modern definition, the
International System of Units (SI), defines the
metric prefixes and seven base units:
metre (m),
kilogram (kg),
second (s),
ampere (A),
kelvin (K),
mole (mol), and
candela (cd).
An
SI derived unit is a named combination of base units such as
hertz (cycles per second),
newton (kg⋅m/s
2), and
tesla (1 kg⋅s
−2⋅A
−1) and in the case of
Celsius a shifted scale from Kelvin. Certain units have been
officially accepted for use with the SI. Some of these are decimalised, like the
litre and
electronvolt, and are considered "metric". Others, like the
astronomical unit are not. Ancient non-metric but SI-accepted multiples of time,
minute and
hour, are base 60 (
sexagesimal). Similarly, the angular measure
degree and submultiples,
arcminute, and
arcsecond, are also sexagesimal and SI-accepted. (
Full article...)
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Image 13Bruno Pontecorvo (
Italian: [ponteˈkɔrvo];
Russian:
Бру́но Макси́мович Понтеко́рво,
Bruno Maksimovich Pontecorvo; 22 August 1913 – 24 September 1993) was an
Italian–
Russian nuclear physicist, an early assistant of
Enrico Fermi and the author of numerous studies in
high energy physics, especially on
neutrinos. A convinced
communist, he
defected to the Soviet Union in 1950, where he continued his research on the decay of the
muon and on neutrinos. The prestigious
Pontecorvo Prize was instituted in his memory in 1995.
The fourth of eight children of a wealthy Jewish-Italian family, Pontecorvo studied physics at the
Sapienza University, under Fermi, becoming the youngest of his
Via Panisperna boys. In 1934 he participated in Fermi's famous experiment showing the properties of slow
neutrons that led the way to the discovery of
nuclear fission. He moved to Paris in 1936, where he conducted research under
Irène and
Frédéric Joliot-Curie. Influenced by his cousin,
Emilio Sereni, he joined the
Italian Communist Party, whose leaders were in Paris as refugees, and as did his sisters Giuliana and Laura and brother
Gillo. The Italian
Fascist regime's
1938 racial laws against Jews caused his family members to leave Italy for Britain, France and the United States. (
Full article...)
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Image 14Bruno Benedetto Rossi (
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...)
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Image 15
Roman copy (in marble) of a
Greek bronze bust of Aristotle by
Lysippos (
c. 330 BC), with modern alabaster mantle
Aristotle (
Attic Greek:
Ἀριστοτέλης,
romanized: Aristotélēs; 384–322 BC) was an
ancient Greek philosopher and
polymath. His writings cover a broad range of subjects spanning the
natural sciences,
philosophy,
linguistics,
economics,
politics,
psychology, and
the arts. As the founder of the
Peripatetic school of philosophy in the
Lyceum in
Athens, he began the wider
Aristotelian tradition that followed, which set the groundwork for the development of modern
science.
Little is known about Aristotle's life. He was born in the city of
Stagira in
northern Greece during the
Classical period. His father,
Nicomachus, died when Aristotle was a child, and he was brought up by a guardian. At around eighteen years old, he joined
Plato's
Academy in Athens and remained there until the age of thirty seven (
c. 347 BC). Shortly after Plato died, Aristotle left Athens and, at the request of
Philip II of Macedon, tutored his son
Alexander the Great beginning in 343 BC. He established a library in the Lyceum, which helped him to produce many of his hundreds of books on
papyrus scrolls. (
Full article...)
The following are images from various physics-related articles on Wikipedia.
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Image 1Star 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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Image 2The 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)
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Image 3Newton's cannonball, a though experiment by Newton relating the motion of a projectile and orbiting of planets. (from
History of physics)
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Image 4Richard Feynman's Los Alamos ID badge (from
History of physics)
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Image 6The
Voltaic pile, the first battery was invented by
Alessandro Volta in 1800 (from
History of physics)
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Image 9Sir Isaac Newton (1642–1727) (from
History of physics)
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Image 10Classical 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)
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Image 11Crookes tube used to study
cathode rays. It lead to the discovery of the
electron by
J. J. Thomson. (from
History of physics)
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Image 12Replica of
William Herschel's telescope used to discover
Uranus (from
History of physics)
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Image 13Composite montage comparing
Jupiter (
left) and its four
Galilean moons (
from top:
Io,
Europa,
Ganymede,
Callisto) (from
History of physics)
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Image 14The first
Bose–Einstein condensate observed in a gas of ultracold
rubidium atoms. The blue and white areas represent higher density. (from
Condensed matter physics)
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Image 15Image of X-ray diffraction pattern from a
protein crystal (from
Condensed matter physics)
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Image 16The
quantum Hall effect: Components of the Hall resistivity as a function of the external magnetic field (from
Condensed matter physics)
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Image 17Classical physics (
Rayleigh–Jeans law, black line) failed to explain
black-body radiation – the so-called
ultraviolet catastrophe. The quantum description (
Planck's law, colored lines) is said to be
modern physics. (from
Modern physics)
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Image 18A
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)
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Image 20Magdeburg hemispheres, an experiment by
Otto von Guericke where two metal hemispheres are held together by vacuum and cannot be separated even if largue forces are applied. (from
History of physics)
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Image 24James Prescott Joule's apparatus for measuring the
mechanical equivalent of heat which the "
work" of the falling weight is converted into the "
heat" of agitation in the water. (from
History of physics)
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Image 25Maxwell's demon, thought experiment by
James Clerk Maxwell to describe the
kinetic theory of gases and describe how a microscopic creature could lead to violations of the
second law of thermodynamics. (from
History of physics)
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Image 26Hydrogen
emission spectrum is discrete (here in log scale). The lines can only be explained with quantum mechanics. (from
History of physics)
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Image 27The ancient Greek mathematician
Archimedes, developer of ideas regarding
fluid mechanics and
buoyancy. (from
History of physics)
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Image 28One 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)
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Image 29Albert Einstein (1879–1955), ca. 1905 (from
History of physics)
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Image 30Christiaan Huygens (1629–1695) (from
History of physics)
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Image 32Computer 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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Image 34Chien-Shiung Wu worked on parity violation in 1956 and announced her results in January 1957. (from
History of physics)
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Image 35A
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)
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Image 37Johannes Kepler's first
law of planetary motion states that planets move in elliptical orbits about the Sun. (from
History of physics)
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Image 38Galileo Galilei (1564–1642), early proponent of the modern scientific worldview and method (from
History of physics)
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Image 39Marie Skłodowska-Curie(1867–1934) received Nobel prizes in physics (1903) and chemistry (1911). (from
History of physics)
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Image 40Einstein proposed that
gravitation results from
masses (or their equivalent energies)
curving ("bending") the
spacetime in which they exist, altering the paths they follow within it. (from
History of physics)
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