Cosmological constants. The cosmological constant, which can be thought of as the density of dark energy in the universe, is a fundamental constant in physical cosmology that has a dimensionless value of approximately 10 −122. Other dimensionless constants are the measure of homogeneity in the universe, denoted by Q, which is explained below by Martin Rees, the …

A mathematical constant is a key number whose value is fixed by an unambiguous definition, often referred to by a symbol (e.g., an alphabet letter), or by mathematicians' names to facilitate using it across multiple mathematical problems. Constants arise in many areas of mathematics, with constants such as e and π occurring in such diverse contexts as geometry, number …

In physics, the fine-structure constant, also known as the Sommerfeld constant, commonly denoted by α (the Greek letter alpha), is a fundamental physical constant which quantifies the strength of the electromagnetic interaction between elementary charged particles.. It is a dimensionless quantity, independent of the system of units used, which is related to the …

In engineering and science, dimensional analysis is the analysis of the relationships between different physical quantities by identifying their base quantities (such as length, mass, time, and electric current) and units of measure (such as miles vs. kilometres, or pounds vs. kilograms) and tracking these dimensions as calculations or comparisons are performed.

Connection to other constants. The Avogadro constant N A is related to other physical constants and properties. It relates the molar gas constant R and the Boltzmann constant k B, which in the SI is defined to be exactly 1.380 649 × 10 …

The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum.A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field.. Permittivity is a material's property that affects the Coulomb ...

Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string (see image); for example, in a musical …

The centimetre–gram–second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time.All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways in which the CGS system was extended to …

The constants listed here are known values of physical constants expressed in SI units; that is, physical quantities that are generally believed to be universal in nature and thus are independent of the unit system in which they are measured.Many of these are redundant, in the sense that they obey a known relationship with other physical constants and can be determined from …

Formal expression. The Madelung constant allows for the calculation of the electric potential of all ions of the lattice felt by the ion at position = where = | | is the distance between the and the ion. In addition, = number of charges of the ion = 1.6022 × 10 −19 C = 1.112 × 10 −10 C 2 /(J⋅m). If the distances are normalized to the nearest neighbor distance , the potential may be written