# Dilation

(Redirected from Dilatation)

Dilation (or dilatation) may refer to:

## Physics

• Scale invariance, a feature of objects or laws that do not change if length scales (or energy scales) are multiplied by a common factor
• Time dilation, the observation that another's clock is ticking at a slower rate as measured by one's own clock

## Music====Mathematics

• Congruence (geometry), being isometric — roughly, the same size and shape
• Congruence or congruence relation, in abstract algebra, an equivalence relation on an algebraic structure that is compatible with the structure
• In modular arithmetic, having the same remainder when divided by a specified integer
• Ramanujan's congruences, congruences for the partition function, p(n), first discovered by Ramanujan in 1919
• Congruence subgroup, a subgroup defined by congruence conditions on the entries of a matrix group with integer entries
• Congruence of squares, in number theory, a congruence commonly used in integer factorization algorithms
• Congruence (manifolds), in the theory of smooth manifolds, the set of integral curves defined by a nonvanishing vector field defined on the manifold
• Congruence (general relativity), in general relativity, a congruence in a four-dimensional Lorentzian manifold that is interpreted physically as a model of space time, or a bundle of world lines
• Zeller's congruence, an algorithm to calculate the day of the week for any date