konstanter

In mathematics and the natural sciences, konstanter (constants) are fixed numerical values that do not change within a given framework. They ground equations, define scales, and can be either abstract numbers from mathematics or physical quantities that describe the properties of nature.

Mathematical constants are universal numbers defined by mathematical relations. Examples include pi (π), the base of natural logarithms e, the golden ratio φ, and the imaginary unit i. Some constants are irrational or transcendental and recur in many areas of math and geometry. They do not depend on measurement or units, only on the consistency of the mathematical system.

Physical constants characterize nature and are presumed invariant across the universe. Examples include the speed of light in vacuum c, Planck's constant h (or the reduced ħ), Newton’s gravitational constant G, elementary charge e, Boltzmann constant k, and Avogadro’s number N_A. Some constants are dimensional, carrying units (for example, c with units of length per time), while others are dimensionless, such as the fine-structure constant α, which quantifies the strength of electromagnetic interaction. Dimensionless constants are particularly important because they are independent of the system of units.

Definitions and measurements: many physical constants are determined experimentally and carry uncertainties, summarized by standards bodies such as CODATA. Some constants are now defined exactly by unit definitions (for example, the speed of light c and certain constants fixed by the 2019 SI redefinition), while others remain measured values.

Historically and practically, konstanter provide the invariant backbone of formulas, enabling precise calculations, comparisons, and the formulation of physical theories. See also mathematical constants, physical constants, and unit definitions.