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quantum theory

(Encyclopedia)quantum theory, modern physical theory concerned with the emission and absorption of energy by matter and with the motion of material particles; the quantum theory and the theory of relativity togethe...

pneumatic tool

(Encyclopedia)pneumatic tool no͝omătˈĭk [key], instrument activated by air pressure. Pneumatic tools are designed around three basic devices: the air cylinder, the vane motor, and the sprayer. The air cylinder ...

Ptolemy

(Encyclopedia)Ptolemy (Claudius Ptolemaeus), fl. 2d cent. a.d., celebrated Greco-Egyptian mathematician, astronomer, and geographer. He made his observations in Alexandria and was the last great astronomer of ancie...

Sontag, Susan

(Encyclopedia)Sontag, Susan sŏnˈtäg [key], 1933–2004, American writer and critic, b. New York City. She grew up in Arizona and California, studied philosophy at the Univ. of Chicago, Harvard, and Oxford, absor...

spinning

(Encyclopedia)spinning, the drawing out, twisting, and winding of fibers into a continuous thread or yarn. From antiquity until the Industrial Revolution, spinning was a household industry. The roughly carded fiber...

Steinbeck, John

(Encyclopedia)Steinbeck, John, 1902–68, American writer, b. Salinas, Calif., studied at Stanford. He is probably best remembered for his strong sociological novel The Grapes of Wrath, considered one of the great ...

Bruno, Giordano

(Encyclopedia)Bruno, Giordano jōrdäˈnō bro͞oˈnō [key], 1548–1600, Italian philosopher, b. Nola. The son of a professional soldier, he entered the Dominican order early in his youth and was ordained a pries...

brake, in technology

(Encyclopedia)CE5 Shoe brake CE5 Disk brake brake, in technology, device to slow or stop the motion of a mechanism or vehicle. The vacuum brake system, or vacuum brake, depends upon the use of a vacuum to ...

energy, sources of

(Encyclopedia)energy, sources of, origins of the power used for transportation, for heat and light in dwelling and working areas, and for the manufacture of goods of all kinds, among other applications. The develop...

magnetism

(Encyclopedia)CE5 Lines of induction around a single bar magnet and between opposite poles of different magnets magnetism, force of attraction or repulsion between various substances, especially those made of i...