Erm, the thrust of my point was that "constants may not be constant, under special conditions" - and an example I gave, as an *extreme* to illustrate how far reality might be from theory, was the use of voltage spikes across a carbon nanotube forest, to induce Casimir-like frequency exclusion and negative-mass-like qualities, for traveling faster than light (and back in time). I hardly expect that example to be a real device; similarly, the fine structure constant *might* be variable with circumstance, equally for the forces driving the expansion of the universe. Picking-apart any particular one of these is missing the point: I don't present *any* of these as plausible pathways to achieving time travel.

Rather, I am arguing that, because we lack *certainty in such areas*, then the observed Fermi Paradox may have another explanation: "Everyone left in their time machines!" None of my examples, time crystals included, were meant as a "Proposed Time Travel Device". They, instead, illustrate our uncertainty on the supposed 'constants'.