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Cepheid variables
(Encyclopedia)Cepheid variables sēˈfēĭd [key], class of variable stars that brighten and dim in an extremely regular fashion. The periods of the fluctuations (the time to complete one cycle from bright to dim a...space-time
(Encyclopedia)space-time, central concept in the theory of relativity that replaces the earlier concepts of space and time as separate absolute entities. In relativity one cannot uniquely distinguish space and time...Kirchhoff's laws
(Encyclopedia)Kirchhoff's laws [for Gustav R. Kirchhoff], pair of laws stating general restrictions on the current and voltage in an electric circuit. The first of these states that at any given instant the sum of ...limit
(Encyclopedia)limit, in mathematics, value approached by a sequence or a function as the index or independent variable approaches some value, possibly infinity. For example, the terms of the sequence 1⁄2, 1⁄4, ...Brahmagupta
(Encyclopedia)Brahmagupta bräˌməgo͝opˈtə [key], c.598–c.660, Indian mathematician and astronomer. He was among the first to meaningfully discuss the concepts of zero and of negative numbers. He wrote in ver...non-Euclidean geometry
(Encyclopedia)non-Euclidean geometry, branch of geometry in which the fifth postulate of Euclidean geometry, which allows one and only one line parallel to a given line through a given external point, is replaced b...Hegel, Georg Wilhelm Friedrich
(Encyclopedia)Hegel, Georg Wilhelm Friedrich gāˈôrkh vĭlˈhĕlm frēˈdrĭkh hāˈgəl [key], 1770–1831, German philosopher, b. Stuttgart; son of a government clerk. Hegel has influenced many subsequent p...amplitude
(Encyclopedia)amplitude ămˈplĭto͞odˌ [key], in physics, maximum displacement from a zero value or rest position. In the harmonic motion of a pendulum, the amplitude of the swing is the greatest distance reache...dimension, in physics
(Encyclopedia)dimension, in physics, an expression of the character of a derived quantity in relation to fundamental quantities, without regard for its numerical value. In any system of measurement, such as the met...altimeter
(Encyclopedia)altimeter ăltĭmˈĭtər, ălˈtĭmēˌtər [key], device for measuring altitude. The most common type is an aneroid barometer calibrated to show the drop in atmospheric pressure in terms of linear e...Browse by Subject
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