Therefore the coupling constant is a dynamical variable in string theory, unlike the case of quantum field theory where it is constant.

If one measures the dynamical variable associated with the operator in this state, one cannot in general predict the outcome with certainty.

From this thought he quickly developed a quantum theory that was based on non-commuting dynamical variables.

The volume becomes a dynamical variable with potential energy and kinetic energy given by .

The same applies to the laws of conservation of dynamical variables.

Professionals speak of this as observing the value of a dynamical variable.

If the metric components are considered the dynamical variables of General Relativity, the condition that the equations are coordinate invariant doesn't have any content by itself.

In other cases, we may have access to only one dynamical variable for our measurements, i.e., we have a scalar time series.

The classical field is treated as a dynamical variable called the canonical coordinate, and its time-derivative is the canonical momentum.

Sources are external fields, fields that contribute to the action, but are not dynamical variables.