Remark: The unstable-data proof retained

The SAE source also gives a phase-space proof. In a transverse bound channel choose longitudinal data supported in $|p_z|\le \kappa /2$, and put $\Omega =\sqrt{{\kappa }^2-{p_z}^2}$. For $u_{\pm }=(f,\pm \Omega f)$,

Robertson's inequality contradicts invariance if both variances are finite. That argument concerns an algebra containing these generally noncompact data. Theorem thm:nogo avoids silently identifying that data algebra with the compact-test algebra.