## TWO-BODIES PROBLEM
^{2)}

← Back

The two-bodies problem is the characteristic one of classical mechanics. It concerns the deterministic interaction of two bodies (in the celestial mechanics sense, for instance) reciprocally related through a simple causal interdependence. Such a problem is easily solved through a differential equation which states how certain quantities and their rates of change are related.

This kind of solution is however based on an implicite postulate, i.e. that such relations are not significantly perturbed by other "bodies". This is the famous lemma "… et ceteris paribus", which is generally invalid in the case of complex systems, even if and when perturbations are slight, some approximate solution may be found.

H. POINCARÉ was first to understand the nature of these difficulties as early as 1892, in his study on the three-bodies problem

### Categories

- 1) General information
- 2) Methodology or model
- 3) Epistemology, ontology and semantics
- 4) Human sciences
- 5) Discipline oriented

### Publisher

Bertalanffy Center for the Study of Systems Science(2020).

To cite this page, please use the following information:

* Bertalanffy Center for the Study of Systems Science (2020).* Title of the entry. In Charles François (Ed.), International Encyclopedia of Systems and Cybernetics (2). Retrieved from www.systemspedia.org/[full/url]

We thank the following partners for making the open access of this volume possible: