[r9etb]

Is this also the fundamental source of the Uncertainty Principle?

The source of the uncertainty principle is that the act of measuring the energy of a particle disturbs its whereabouts, and finding the position of a particle disturbs its energy. You can't know both at the same time, because you can't measure them both at the same time.

This is not (to my simple mind) the same as saying that the particles don't have specific position and energy, but just that we can't know them.

[Doctor Stochastic]

Actual the uncertainty principle is a result of the wave-nature of things. It comes out of the theory of the Fourier transform.

The Aspect experiments and the analyses of the EPR paradox make it problematical whether a particle actually "has" position or momentum. QM sidesteps this by saying what the result of a measurement will be, not what a particle "has."