Portal:Physics/2014 Selected pictures

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Replacement filing cabinet.svg This is an archive of the entries that have appeared or will appear on the Wikipedia Physics Portal.

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January[edit]

Estimated distribution of matter and energy in the universe, today (top) and when the CMB was released (bottom)

Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior. Among the objects studied are galaxies, stars, planets, extrasolar planets, the interstellar medium and the cosmic microwave background. Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including classical mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic, molecular, and optical physics.

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February[edit]

An illustration of the Double Slit Experiment

Light from one slit interferes with light from the other, producing an interference pattern (the 3 fringes shown at the right).
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March[edit]

Difference between classical and modern physics[edit]

The basic domains of 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.

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April[edit]

Archimedes' screw, also called the Archimedean screw or screwpump, is a machine historically used for transferring water from a low-lying body of water into irrigation ditches. The screw pump is commonly attributed to Archimedes on the occasion of his visit to Egypt, but this tradition may reflect only that the apparatus was unknown to the Greeks before Hellenistic times and introduced in his lifetime by unknown Greek engineers, although some writers have suggested the device may have been in use in Assyria some 350 years earlier.

Images (from left to right):[edit]

Archimedes' screw was operated by hand and could raise water efficiently
An Archimedes' screw in Huseby south of Växjö Sweden
Archimedes' screw
Roman screw used to dewater mines in Spain
Modern Archimedes' screws which have replaced some of the windmills used to drain the polders at Kinderdijk in the Netherlands
Archimedes' screw as a form of art by Tony Cragg at 's-Hertogenbosch in the Netherlands
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May[edit]

The Copernican Revolution[edit]

The Copernican Revolution was the paradigm shift from the Ptolemaic model of the heavens, which described the cosmos as having Earth stationary at the center of the universe, to the heliocentric model with the Sun at the center of the Solar System. Beginning with the publication of Nicolaus Copernicus’s De revolutionibus orbium coelestium, contributions to the “revolution” continued until finally ending with Isaac Newton’s work over 200 years later.

Motion of Sun, Earth, and Mars according to heliocentrism (left) and to geocentrism (right), before the Copernican-Galilean-Newtonian revolution. Note the retrograde motion of Mars on the right. Yellow dot, Sun; blue, Earth; red, Mars.
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June[edit]

An illustration of the Double Slit Experiment

Light from one slit interferes with light from the other, producing an interference pattern (the 3 fringes shown at the right).
edit


July[edit]

Archimedes' screw, also called the Archimedean screw or screwpump, is a machine historically used for transferring water from a low-lying body of water into irrigation ditches. The screw pump is commonly attributed to Archimedes on the occasion of his visit to Egypt, but this tradition may reflect only that the apparatus was unknown to the Greeks before Hellenistic times and introduced in his lifetime by unknown Greek engineers, although some writers have suggested the device may have been in use in Assyria some 350 years earlier.

Images (from left to right):[edit]

Archimedes' screw was operated by hand and could raise water efficiently
An Archimedes' screw in Huseby south of Växjö Sweden
Archimedes' screw
Roman screw used to dewater mines in Spain
Modern Archimedes' screws which have replaced some of the windmills used to drain the polders at Kinderdijk in the Netherlands
Archimedes' screw as a form of art by Tony Cragg at 's-Hertogenbosch in the Netherlands
edit


August[edit]

Difference between classical and modern physics[edit]

The basic domains of 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.

edit


September[edit]

The Copernican Revolution[edit]

The Copernican Revolution was the paradigm shift from the Ptolemaic model of the heavens, which described the cosmos as having Earth stationary at the center of the universe, to the heliocentric model with the Sun at the center of the Solar System. Beginning with the publication of Nicolaus Copernicus’s De revolutionibus orbium coelestium, contributions to the “revolution” continued until finally ending with Isaac Newton’s work over 200 years later.

Motion of Sun, Earth, and Mars according to heliocentrism (left) and to geocentrism (right), before the Copernican-Galilean-Newtonian revolution. Note the retrograde motion of Mars on the right. Yellow dot, Sun; blue, Earth; red, Mars.
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October[edit]

Estimated distribution of matter and energy in the universe, today (top) and when the CMB was released (bottom)

Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior. Among the objects studied are galaxies, stars, planets, extrasolar planets, the interstellar medium and the cosmic microwave background. Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including classical mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic, molecular, and optical physics.

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November[edit]

André-Marie Ampère
Ampere Andre 1825.jpg
Engraving of André-Marie Ampère
Born (1775-01-20)20 January 1775
Lyon, France
Died 10 June 1836(1836-06-10) (aged 61)
Marseille, France
Nationality French
Fields Physics
Institutions École Polytechnique
Known for Ampère's circuital law, Ampère's force law
Signature

André-Marie Ampère (20 January 1775 – 10 June 1836) was a French physicist and mathematician who is generally regarded as one of the main founders of the science of classical electromagnetism, which he referred to as "electrodynamics". The electric current unit of measurement known as the ampere is named after him.

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December[edit]

The Arc lamp[edit]

An arc lamp or arc light is a lamp that produces light by an electric arc (also called a voltaic arc). The carbon arc light, which consists of an arc between carbon electrodes in air, invented by Humphry Davy in the early 1800s, was the first practical electric light. It was widely used starting in the 1870s for street and large building lighting until it was superseded by the incandescent light in the early 20th century. It continued in use in more specialized applications where a high intensity point light source was needed, such as searchlights and movie projectors until after World War II.

The 15 kW xenon short-arc lamp used in the IMAX projection system.
A mercury arc lamp from a fluorescence microscope.
A krypton long arc lamp (top) is shown above a xenon flashtube. The two lamps, used for laser pumping, are very different in the shape of the electrodes, in particular, the cathode, (on the left).
A krypton arc lamp during operation.
An electric arc, demonstrating the “arch” effect.
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