Time scale may refer to:
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Time standard
A time standard is a specification for measuring time: either the rate at which time passes or points in time or both. In modern times, several time specifications have been officially recognized as standards, where formerly they were matters o ...
, a specification of either the rate at which time passes, points in time, or both
*A duration or quantity of time:
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Orders of magnitude (time)
An order of magnitude of time is usually a decimal prefix or decimal order-of-magnitude quantity together with a base unit of time, like a microsecond or a million years. In some cases, the order of magnitude may be implied (usually 1), like a ...
as a power of 10 in seconds;
**A specific
unit of time
A unit of time is any particular time interval, used as a standard way of measuring or expressing duration. The base unit of time in the International System of Units (SI) and by extension most of the Western world, is the second, defined as a ...
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Geological time scale, a scale that divides up the history of Earth into scientifically meaningful periods
In astronomy and physics:
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Dynamical time scale
In time standards, dynamical time is the independent variable of the equations of celestial mechanics. This is in contrast to time scales such as mean solar time which are based on how far the earth has turned. Since Earth's rotation is not cons ...
, in stellar physics, the time in which changes in one part of a body can be communicated to the rest of that body, or in celestial mechanics, a realization of a time-like argument based on a dynamical theory
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Nuclear timescale
In astrophysics, the nuclear timescale is an estimate of the lifetime of a star based solely on its rate of fuel consumption. Along with the thermal and free-fall (aka dynamical) time scales, it is used to estimate the length of time a particul ...
, an estimate of the lifetime of a star based solely on its rate of fuel consumption
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Thermal time scale
In astrophysics, the thermal time scale or Kelvin-Helmholtz time scale is the approximate time it takes for a star to radiate away its total kinetic energy content at its current luminosity rate. Along with the nuclear and free-fall (aka dyna ...
, an estimate of the lifetime of a star once the fuel reserves at its center are used up
In cosmology and particle physics:
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Planck time, the time scale beneath which quantum effects are comparable in significance to gravitational effects
In mathematics:
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Time-scale calculus In mathematics, time-scale calculus is a unification of the theory of difference equations with that of differential equations, unifying integral and differential calculus with the calculus of finite differences, offering a formalism for studying ...
, the unification of the theory of difference equations with differential equations
In music:
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Rhythm
Rhythm (from Greek , ''rhythmos'', "any regular recurring motion, symmetry") generally means a " movement marked by the regulated succession of strong and weak elements, or of opposite or different conditions". This general meaning of regular re ...
, a temporal pattern of events
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Time scale (music)
Rhythm (from Greek , ''rhythmos'', "any regular recurring motion, symmetry") generally means a " movement marked by the regulated succession of strong and weak elements, or of opposite or different conditions". This general meaning of regular recu ...
, which divides music into sections of time
In project management:
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Man-hour
A man-hour (sometimes referred to as person-hour) is the amount of work performed by the average worker in one hour. It is used for estimation of the total amount of uninterrupted labor required to perform a task. For example, researching and wr ...
, the time scale used in project management to account for human labor planned or utilized
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