Physics

The Physics Portal

Physics (from Greek φυσική (ἐπιστήμη), i.e. "knowledge of nature", from φύσις, physis "nature"), is the natural science that involves the study of matter and its motion 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 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.

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Below are links to pages that are rated "Good Article" within WikiProject Physics from letters "M" thru "W" and "X". The small good article icon (), 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.

John Marburger Maximum sustained wind James Clerk Maxwell Boyce McDaniel Metric system Mirror symmetry (string theory) Nature Newton's theorem of revolving orbits Noctilucent cloud Mark Oliphant Optical properties of carbon nanotubes Plasma (physics) Proposed redefinition of SI base units Quantum electrodynamics Isidor Isaac Rabi RaLa Experiment Norman Foster Ramsey, Jr. Retrocausality George T. Reynolds Bruno Rossi Safety of high energy particle collision experiments

Saffir–Simpson hurricane wind scale Schiehallion experiment Glenn T. Seaborg Emilio G. Segrè Henry DeWolf Smyth Smyth Report Solar energy Storm surge Surface tension Thin Man (nuclear bomb) Tropical cyclone scales Type Ia supernova Type Ib and Ic supernovae Type II supernova Waterspout Weak interaction Wetting Wind power Wind shear Leona Woods Wright brothers X-ray crystallography

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Difference between classical and modern physics

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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Did you know...

Mock mirage of the setting sun

• ...the mirage of astronomical objects is an optical phenomenon, which produces distorted or multiple images of astronomical objects such as the Sun, the Moon, the planets, bright stars and very bright comets

• ...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.

• ...that, in the Large Hadron Collider, protons move at 99.9999991% of the speed of light when accelerated to the energy of 7 TeV?

• ...that, at a speed of 299,792,458 m/s, light can travel from the Earth to the Moon in 1.2 seconds?

• ...that the submarine telescope ANTARES, intended to detect neutrinos, may also be used to observe bioluminescent plankton and fish?

Artist's depiction of the WMAP satellite measuring the Cosmic Microwave Background Radiation to help scientists understand the Big Bang

• ...that lasers can be used to separate two isotopes very efficiently?

• ...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 gold leaf is about 500 atoms thick?

• ...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?

• ...that Neptune was discovered by its gravitational pull on Uranus?