Necessary additions to the paper by Yu M Tsipenyuk [Phys. Usp. 55 796 (2012)] and to the review by B A Knyazev, V G Serbo [Phys. Usp. 61 449 (2018)]

This letter, which provides a more detailed description of zero-point vibrations and the Sadovskii effect, is an addition to the papers: Yu M Tsipenyuk “Zero point energy and zero point oscillations: how they are detected experimentally” Phys. Usp. 55 796 (2012) and B A Knyazev, V G Serbo “Beams of photons with nonzero projections of orbital angular momenta: new results” Phys. Usp. 61 449 (2018).