observable
From Physics wiki
An observable is any quantity of a system that may be measured in an experiment, be it the position or momentum of a particle, the spectrum of electromagnetic radiation emmitted in some process, or the intrinsic angular momentum of an atom. The name is to distinguish it from quantities that cannot be observed, e.g. the absolute phase of a wavefront or the electromagnetic vector potential.
back to Matrix Mechanics
on to measurement
In quantum mechanics, an observable is associated with a certain Hermitian operator acting on a Hilbert space.
