Portal:Physics

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A stylized depiction of a Lithium atom.

Physics (from Greek φυσική (ἐπιστήμη), i.e. "knowledge of nature", from φύσις, physis "nature"), is the natural science that involves the study of matter (anything that has mass and occupies space) and its motion (movement from place to another) through space and time, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.

Physics is one of the oldest academic disciplines, perhaps the oldest through its inclusion of astronomy. Evidence exists that the earliest civilizations dating back to beyond 3000 BCE, such as the Sumerians, Ancient Egyptians, and the Indus Valley Civilization, all had a predictive knowledge and a very basic understanding of the motions of the Sun, Moon, and stars. Although originally part of other physical sciences and mathematics, Physics emerged to become a unique modern science during the Scientific Revolution of the 16th century.

Physics is both significant and influential, in part because advances in its understanding have often translated into new technologies, but also because new ideas in physics often resonate with other sciences, mathematics, and philosophy. For example, advances in the understanding of electromagnetism or nuclear physics led directly to the development of new products which have dramatically transformed modern-day society (e.g., television, computers, domestic appliances, atomic power, and nuclear weapons); advances in thermodynamics led to the development of motorized transport and advances in aviation engineering; and advances in mechanics inspired the development of calculus.

Physics also has philosophical implications. It can be historically traced back to ancient Greek philosophy. From Thales' first attempt to characterize matter, to Democritus' deduction that matter ought to reduce to an invariant state, the Ptolemaic astronomy of a crystalline firmament, and Aristotle's book Physics, different Greek philosophers advanced their own theories of nature. Well into the 18th century, physics was known as "Natural philosophy". By the 19th century physics was realized as a positive science and a distinct discipline separate from philosophy and the other sciences. Physics, as with the rest of science, relies on philosophy of science to give an adequate description of the scientific method. Template:/box-footer

Template:/box-header Below are links to pages that are rated "Good Article" within WikiProject Physics from letters "A" through "L". The small good article icon (Good article), which can be found on the top right corner of a rated Wikipedia page, symbolizes content held to a high standard on Wikipedia, although these have not reached Featured Article status.

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The Arc lamp

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.
File:Krypton arc lamp and a xenon flashlamp.JPG
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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Template:/box-header europa is a moon of jupiter.europa is smooth and icy and may contain water.

  • ...that if the galaxy Andromeda were bright enough to be fully visible to the naked eye it would appear six times as wide as our moon?
  • ...that your watch would run slower when orbiting a black hole than it would on Earth?
  • ...that Aristotle's ideas of physics held that because an object could not move without an immediate source of energy, arrows created a vacuum behind them that pushed them through the air.
  • ...that nuclear fusion reactions are probably occurring at or above the sun's photosphere; it is a process called solar surface fusion.
Artist's depiction of the WMAP satellite measuring the Cosmic Microwave Background Radiation to help scientists understand the Big Bang
  • ...that neutron stars are so dense that a teaspoonful (5 mL) would have ten times the mass of all human world population?
  • ...that every year, the Moon moves 3.82 cm away from Earth?
  • ...that the Big Bang was secured as the best theory of origin of the universe by the discovery of the cosmic microwave background radiation in 1964?
  • ...light takes 8.3 minutes to reach the earth's surface from the sun?
  • ... the temperature of the infant universe was 2 billion billion°C but only for 1 millionth of a trillionth of a trillionth (1×10^30) of a second?
  • ...that Neptune was discovered by its gravitational pull on Uranus?
  • ...that gravitational force is one of the weakest forces?
  • ...that the sun revolves the centre of Milky Way in 250 million years?


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Summary

Whether you are an expert or a novice, be bold, improve an article by editing it. Practice in the sandbox if you must. But hurry back to fix that glaring error that has been bothering you.

Check list for physics novices and experts new to wikipedia

Whether you are an expert or a novice, be bold, improve an article by editing it. Practice in the sandbox if you must. But hurry back to fix that glaring error that has been bothering you.

Activities for physics novices and experts familiar with wikipedia

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Portal:Astronomy
Portal:Electromagnetism
Portal:Cosmology
Astronomy Electromagnetism Cosmology Gravitation

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The following Wikimedia sister projects provide more on this subject:
Wikibooks  Wikimedia Commons Wikinews  Wikiquote  Wikisource  Wikiversity  Wikivoyage  Wiktionary  Wikidata 
Books Media News Quotations Texts Learning resources Travel guides Definitions Database

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