field

Field

 Stan Zurek, Field, Encyclopedia Magnetica, http://www.e-magnetica.pl/doku.php/field

Field - a concept used in physics to describe and explain interactions of energy or matter, such that every point in space can take a different value of a given physical quantity, in the form of a scalar, vector, or tensor, making it a scalar field, vector field, or tensor field, accordingly.1)

In particular, electromagnetic field contains energy and has momentum associated with it, so the concept of a field is useful for describing and explaining action-at-distance, especially for electric field, magnetic field and gravitational field. No information can travel faster than the speed of light, and therefore any changes in the field (such as electromagnetic pulse) cannot travel faster than that.2)

Appropriate mathematical notation of a field allows mathematical analysis of the involved quantities, so that the solutions of equations can be provided for known parameters of involved excitations, geometries, and material properties. This concept is fundamental for such numerical techniques as finite element method or finite difference element method, or similar.

Iron filings visualise the local magnetic field around a horseshoe magnet
Particles floating on insulating oil visualise the electric field between the two electrodes by Mike Run, CC-BY-4.0
Thermal image visualises the thermal field (i.e. temperature)