Portal:Physics

The Physics Portal

Physics (Greek: physis – φύσις meaning "nature") is a natural science that involves the study of the fundamentals that govern the universe, dimensions, and energy or matter. This has led to the discovery and understanding of the laws and principles which govern the physical universe - as perceived by earthlings. More broadly, Physics is the general analysis of nature, conducted in order to understand how the world and universe behave. One tool which helps with this general analysis is the study of the elementary constituents of the universe and their interactions.

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.

Selected article

A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. As white dwarfs have mass comparable to the Sun's and their volume is comparable to the Earth's, they are very dense. Their faint luminosity comes from the emission of stored heat. They comprise roughly 6% of all known stars in the solar neighbourhood The unusual faintness of white dwarfs was first recognized in 1910 by Henry Norris Russell, Edward Charles Pickering and Williamina Fleming, and the name white dwarf was coined by Willem Luyten in 1922. White dwarves continue to lose energy and fade, becoming Black dwarfs...

Selected picture

A false colour image of Tycho's Supernova Remnant, of Tycho's Supernova of 1572.

Did you know...

• ...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 be at a different time orbiting a black hole than it would be 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?

• ...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 if we travel at the speed of light it would take us no time at all to cross the universe according to our watches?

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

Physics topics

Classical physics traditionally includes the fields of mechanics, optics, electricity, magnetism, acoustics and thermodynamics. The term Modern physics is normally used for fields which rely heavily on quantum theory, including quantum mechanics, atomic physics, nuclear physics, particle physics and condensed matter physics. General and special relativity are usually considered to be part of modern physics as well.

Fundamental Concepts	Classical Physics	Modern Physics	Cross Discipline Topics
Space	Classical Mechanics	Special Relativity and General Relativity	Mathematical Physics
Time	Electromagnetism	Quantum Mechanics	Astronomy
Matter	States of Matter	Quantum Field Theory	Chemical Physics
Energy	Thermodynamics	Quantum Gravity	Materials Science
Electromagnetism	Solid Mechanics	Condensed Matter Physics	Geophysics
Strong interaction	Fluid Mechanics	Atomic Physics	Biophysics
Weak interaction	Acoustics	Nuclear Physics	Nanotechnology
Gravitational Field	Optics	Particle Physics
Entropy		Plasma Physics