# Idealization (physics)

An **idealization** is a model of reality that does not take into account certain facts and disruptive influences. Depending on the problem, effects that are difficult to formulate are not included in the model under consideration, in order to be able to solve the problem at all (simplification) or to be able to present facts more concisely (concentration). The process of mapping reality in a model is known as modeling .

Every physical model is an idealization, since interactions with the environment are partially excluded or only come into play via effective values .

Consider the earth as an example of different hierarchies of idealization :

- To calculate the ecliptic (plane of its annual orbit) it can be assumed as a mass point in the gravitational field of the sun .
- On the other hand, in order to determine a position on earth, one must at least define it as a sphere with a certain radius.
- For geometrically more precise location information (e.g. in national surveys or GPS methods), the globe must be replaced by a precisely defined earth ellipsoid .
- The best model surface for height information , however, is the geoid . Although it is given by the earth's mass distribution , it can only be described mathematically on the basis of precise measurements in nature.
- In thought, the earth could become the ideal equilibrium model if all height differences were leveled and covered by an evenly deep sea while maintaining the earth's mass .

Other prominent models for idealizations are:

- in physics the ideal gas , the rigid body and the laminar flow ,
- in astrophysics the black body in radiation equilibrium or the exactly elliptical planetary motion in the two-body problem ,
- in geophysics an even stratification of the earth's interior
- in technology, the chain and bending line or the architecturally ideal city .