A point particle (or point-like, often spelled pointlike) is an idealized object heavily used in physics. Its defining feature is that it lacks spatial extension: being zero-dimensional, it does not take up space. A point particle is an appropriate representation of any object whose size, shape, and structure is irrelevant in a given context. For example, from far enough away, an object of any shape will look and behave as a point-like object.

Sometimes due to specific combinations of properties extended objects behave as point-like even in their immediate vicinity. For example, spherical objects interacting in 3-dimensional space in a particular manner called the inverse square law behave in such a way as if all their matter were concentrated in the geometric centers of their spherical shapes. In Newtonian gravitation and classical electromagnetism, for example, the respective fields outside of a spherical object are identical to those of a point particle of equal charge/mass located at the center of the sphere.

In particle physics, whose theoretical framework is quantum field theory, "point particle" is synonymous with "elementary particle", which is defined as a particle without structure or, equivalently, as a particle lacking component parts. According to the Standard Model (of fundamental particles and forces), quarks, leptons and the (non-composite) vector bosons are point particles in this sense.

See also

• Point mass
• Point charge

External links

• The shapes of things

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