This article is about relational theory in physics. There is a separate article about the relational model.

In physics and philosophy, a relational theory is a framework to understand reality or a physical system in such a way that the position and other properties of the objects are only meaningful relatively to other objects. In a relational theory, space does not exist unless there are objects in it.

The alternative is an absolute theory in which the space exists independently of any objects that can be immersed in it.

The relational point of view was advocated by Gottfried von Leibniz, Ernst Mach (in his Mach's principle), and it was rejected by Isaac Newton in his successful description of classical physics. Although Albert Einstein was impressed by Mach's principle, he was unable to fully incorporate it into his theory of general relativity. Several attempts have been made to formulate a full Machian theory, but none have so far succeeded. For example, see Brans-Dicke theory.

A developing theory of gravity, loop quantum gravity, is revisiting the relational view.

See also

• Holism