Of course, and I do appreciate your reply. I was purposefully vague in my original wording because there is that niggling difference between &quot;unphysical&quot; and &quot;not proved impossible&quot; that I didn&#x27;t want to get on the wrong side of. You have enabled me to speak more precisely about the subject in the future -- many thanks. My last reply was merely trying to place this information in context; that is to say not unphysical, but in the same category as stable wormholes, Alcubierre drives, FTL&#x2F;time travel, and other such theories. And ultimately it seems like either the guy talking about graviton beams was either talking about something extremely far-fetched, or a great way to destroy large parts of the planet, or both.