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elementary particles

(Encyclopedia)CE5 elementary particles, the most basic physical constituents of the universe. The first subatomic particle to be discovered was the electron, identified in 1897 by J. J. Thomson. After the...

geologic timescale

(Encyclopedia)CE5 geologic timescale, a chronological scale of earth's history used to measure the relative or absolute age of any part of geologic time. Of the numerous timescales, the most common is based on g...

second

(Encyclopedia)second, abbr. sec or s, fundamental unit of time in all systems of measurement. In practical terms, the second is 1/60 of a minute, 1/3,600 of an hour, or 1/86,400 of a day. Since the length of the da...

Janus, in Roman religion

(Encyclopedia)Janus jāˈnəs [key], in Roman religion, god of beginnings. He was one of the principal Roman gods, the custodian of the universe. The first hour of the day, the first day of the month, the first mon...

occultation

(Encyclopedia)occultation ŏkˌəltāˈshən [key], in astronomy, eclipse of one celestial body by another, e.g., when the moon lies between a star and the earth. Occultations of stars by the moon are important in ...

laser printer

(Encyclopedia)laser printer, a computer printer that produces high-resolution output by means of a process that is similar to photocopying. In place of reflected light from an image (as is used in xerography), a la...

Mendeleev, Dmitri Ivanovich

(Encyclopedia)Mendeleev, Dmitri Ivanovich mĕndəlāˈəf, Rus. dəmēˈtrē ēväˈnəvĭch myĭndyĭlyāˈəf [key], 1834–1907, Russian chemist. He is famous for his formulation (1869) of the periodic law and t...

Kraepelin, Emil

(Encyclopedia)Kraepelin, Emil krĕpəlēnˈ [key], 1856–1926, German psychiatrist, educated at Würzburg (M.D., 1878). He also studied under Wilhelm Wundt in Leipzig, and was appointed professor of psychiatry at ...

Müller, Max

(Encyclopedia)Müller, Max (Friedrich Maximilian Müller, Friedrich Max Müller, or Friedrich Max-Müller) ;frēˈdrĭkh mäkˌsēmēlˈyän [key], 1823–1900, German philologist and Orientalist, b. Dessau; son of...

Holly, Buddy

(Encyclopedia)Holly, Buddy, 1936–59, American rock singer, songwriter, and guitarist, b. Lubbock, Tex., as Charles Hardin Holley. He performed country and western m...