Columbia Encyclopedia

Search results

325 results found

interference

(Encyclopedia)CE5 Constructive interference: Two crests or two troughs meet and combine (A, B, C). Destructive interference: A crest and a trough meet and cancel each other (D, E, F). interference, in physics, ...

dew

(Encyclopedia)dew, thin film of water that has condensed on the surface of objects near the ground. Dew forms when radiational cooling of these objects during the nighttime hours also cools the shallow layer of ove...

crossing over

(Encyclopedia)crossing over, process in genetics by which the two chromosomes of a homologous pair exchange equal segments with each other. Crossing over occurs in the first division of meiosis. At that stage each ...

Local Group

(Encyclopedia)Local Group, in astronomy, loose cluster of at least 40 nearby galaxies, including our own Milky Way galaxy, the Andromeda Galaxy, and the Magellanic Clouds. The Local Group is spread over an ellipsoi...

McCarthy, Gina

(Encyclopedia) McCarthy, Gina (Regina McCarthy), 1954- , American environmentalist and government official, Brighton, Ma., Univ. of Ma., Boston (B.A., 1976), Tufts U...

Price, Reynolds

(Encyclopedia)Price, Reynolds (Edward Reynolds Price), 1933–2011, American writer, b. Macon, N.C., grad. Duke Univ. (A.B., 1955), Oxford (B.Litt., 1958). He began teaching at Duke in 1958 and remained there for m...

Uppsala

(Encyclopedia)Uppsala ŭpˈsələ, –säˌlä [key], city (1990 pop. 109,500), capital of Uppsala co., E Sweden, on the Fyrisån River. It is an industrial and cultural center and a railroad junction. Manufactures...

Sagan, Carl Edward

(Encyclopedia)Sagan, Carl Edward sāˈgən [key], 1934–96, American astronomer and popularizer of science, b. New York City. Early in his career he investigated radio emissions from Venus and concluded that the c...

cosmology

(Encyclopedia)cosmology, area of science that aims at a comprehensive theory of the structure and evolution of the entire physical universe. The earliest pre-Ptolemaic theories assumed that the earth was the cent...

pump

(Encyclopedia)pump, device to lift, transfer, or increase the pressure of a fluid (gas or liquid) or to create a vacuum in an enclosed space by the removal of a gas (see vacuum pumps under vacuum). The centrifugal ...