Columbia Encyclopedia

Search results

104 results found

color index

(Encyclopedia)color index, in astronomy, difference in an object's brightness as recorded between any two well-defined bands of the electromagnetic spectrum by using optical filters of different colors. If blue and...

albedo

(Encyclopedia)albedo ălbēˈdō [key], reflectivity of the surface of a planet, moon, asteroid, or other celestial body that does not shine by its own light. Albedo is measured as the fraction of incident light th...

Gregory, Wilton Daniel

(Encyclopedia)Gregory, Wilton Daniel, 1947–, American Roman Catholic cardinal, b. Chicago. Ordained in 1973, he was educated at Niles College (now St. Joseph's College Seminary) of Loyola Univ., Chicago, St. Mary...

potential, electric

(Encyclopedia)potential, electric, work per unit of electric charge expended in moving a charged body from a reference point to any given point in an electric field (see electrostatics). The potential at the refere...

Sitter, Willem de

(Encyclopedia)Sitter, Willem de vĭlˈəm də sĭtˈər [key], 1872–1934, Dutch astronomer and mathematician. He was professor from 1908 at the Univ. of Leiden and in 1919 became director of its observatory. His ...

algebra

(Encyclopedia)algebra, branch of mathematics concerned with operations on sets of numbers or other elements that are often represented by symbols. Algebra is a generalization of arithmetic and gains much of its pow...

Nernst, Walther Hermann

(Encyclopedia)Nernst, Walther Hermann välˈtər hĕrˈmän nĕrnst [key], 1864–1941, German physicist and chemist, a founder of modern physical chemistry. After doing outstanding research on osmotic pressure and...

odometer

(Encyclopedia)odometer ōdŏmˈĭtər [key], instrument provided in an automotive vehicle to indicate the total number of miles that have been traveled. The odometer generally shares a housing with the vehicle's sp...

Barthes, Roland

(Encyclopedia)Barthes, Roland rôläNˈ bärt [key], 1915–80, French critic. Barthes was one of the founding figures in the theoretical movement centered around the journal Tel Quel. In his earlier works, such as...

cryotron

(Encyclopedia)cryotron krīˈōtrŏnˌ [key], magnetically controlled electronic switching device that operates at extremely low temperatures; it is designed to supplant, in part, the transistor in special electron...