Music is an art form and cultural activity whose medium is sound organized in time. The common elements of music are pitch (which governs melody and harmony), rhythm (and its associated concepts tempo, meter, and articulation), dynamics (loudness and softness), and the sonic qualities of timbre and texture (which are sometimes termed the "color" of a musical sound). Different styles or types of music may emphasize, de-emphasize or omit some of these elements. Music is performed with a vast range of instruments and vocal techniques ranging from singing to rapping; there are solely instrumental pieces, solely vocal pieces (such as songs without instrumental accompaniment) and pieces that combine singing and instruments. The word derives from Greek μουσική (mousike; "art of the Muses"). See glossary of musical terminology.
In physics, sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid.
A thousand trills and quivering sounds In airy circles o'er us fly, Till, wafted by a gentle breeze, They faint and languish by degrees, And at a distance die.
Sonorous metal blowing martial sounds, At which the universal host up sent A shout that tore hell's concave, and beyond Frighted the reign of Chaos and old Night.
John Milton, Paradise Lost (1667; 1674), Book I, line 540.
Solar power is potentially an almost limitless resource. The sun provides enough energy in one minute to supply the world’s energy needs for one year. But turning this resource into affordable electricity is difficult – silicon-based solar cells still suffer from a decline in their effectiveness over time. Through her ERC-funded SOLARX project, Professor Hele Savin, of Aalto University in Finland, is investigating a possible route to solving this problem.