Graviscalar

In theoretical physics, a graviscalar (also known as a radion) is a hypothetical particle that emerges as an excitation of the metric tensor (i.e. gravitational field) but whose physical properties are virtually indistinguishable from a scalar in four dimensions, as shown in Kaluza–Klein theory. The scalar field comes from a component of the metric tensor where the figure 5 labels an additional, fifth dimension. It can be thought of as a measure of the size of the extra dimension, with variations in the scalar field representing variations in the size of the extra dimensions.