 | Matter: Encyclopedia - Matter
Matter
Matter is commonly referred to as the substance of which physical objects are composed. It constitutes the observable Universe. According to the theory of relativity there is no distinction between matter and energy, because matter can be converted to energy (see annihilation), and vice versa (see matter creation). Philosophically, matter constitutes the formless substratum of all things, which exists only potentially and from which reality is produced. In the sense of content, matter is also used in contrast to form.
Matter - Matter in Science
In physics, it is everything that is constituted of elementary fermions. Matter occupies space and has mass. It is composed predominantly of atoms, which consist of protons, neutrons, and electrons. All gauge bosons (of which the photon is one), which mediate the four fundamental forces, are not considered matter, even though they certainly have energy and some also mass.
Matter thus consists of quarks and leptons. There are six types of quarks (strange, charm, top, bottom, up, and down) which combine to form hadrons, primarily baryons and mesons, through the strong interaction and are actually thought to always be confined. Among the baryons are the proton and the neutron, which further combine to form the nuclei of all elements of the periodic table. Usually these nuclei are surrounded by a cloud of electrons. A nucleus with as many electrons as protons, which is thus electrically neutral, is called an atom, otherwise it is an ion.
In bulk, matter can exist in several different phases, according to particle density and energy density or alternatively pressure and temperature. These phases include gases, plasmas, liquids, fluids, superfluids, solids, and Bose-Einstein condensate. As circumstances change, matter may change from one phase into another. These phenomena are called phase transitions, and their energetics are studied in the field of thermodynamics. In small quantities, matter can exhibit properties that are entirely different from those of bulk material.
Homogeneous matter has a definite composition and properties and any amount of the matter has the same composition and properties. Homogenous matter may or may not be a mixture. Iron and brass would examples of each. Heterogeneous matter does not have a definite composition, for example, granite.
In chemistry, matter is often restricted to chemical substances, as elementary particles like quarks and leptons have not been subject of any chemical reactions.
Antimatter, Materialism, Particle physics (provides a historical background), Phases of matter
See also
- Antimatter
- Materialism
- Particle physics (provides a historical background)
- Phases of matter
Category: Matter
Other related archivesAntimatter, Bose-Einstein condensate, Materialism, Matter, Particle physics, Phases of matter, Philosophically, annihilation, atom, atoms, baryons, bulk, chemical reactions, chemical substances, chemistry, content, electrons, elementary, elements, energy, energy density, fermions, fluids, form, four fundamental forces, gases, gauge bosons, hadrons, ion, leptons, liquids, mass, matter creation, mesons, neutrons, nuclei, observable Universe, periodic table, phase transitions, phases, photon, physics, plasmas, pressure, protons, quarks, solids, space, strong interaction, superfluids, temperature, theory of relativity, thermodynamics
 Adapted from the Wikipedia article "Matter", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki |
