For those who might be a mite curious, Stop Fittling With That is set in “present-time” – that is to say, the furthest future point of my defined timeline (although, obviously, not the end of their history), so those mentioned technologies are things that won’t actually appear anywhere in the Eldraeverse, certainly not in the context of the peoples of the Associated Worlds.

FTL (other than the mentioned wormholes and tangle channels) won’t appear at all, and in fact is canonically impossible by other means using my conphysics; for reasons which boil down to “it interferes with the kind of stories I want to tell and the kind of technologies I want to use to tell them”.  Such forms of FTL as wouldn’t – like, say, mass relays – are for the most part functionally isomorphic to the wormhole network I chose to go with anyway.

Dimensional transcendence just hasn’t been invented yet – any examples of it you may see are faked by means which you’ll read about when the Trope-a-Day catches up to, ah, Hammerspace, I think – but is permitted by the local conphysics.  (If you can bend space and time enough to do practical, mass-produced wormholes, bending them enough to put a decent-sized mansion inside a police box is for the most part merely a matter of working out the engineering – for very large values of “merely”.)

Negentropy or something like it probably will require the ability to not merely bend but actually drill holes in the universe, and so is deep-time lengths of time away if it’s possible at all.  Which it may well not be, but I don’t plan on arbitrarily declaring the greatest expression of their greatest ambition physically off-limits when I can just Shrug of God it into the indefinite far future.

And both matter translocation/teleportation and instant Star Trek replicator-style manufacturing don’t exist for the same two reasons.  First, Heisenberg…

(Or rather, in-world, Jeness Rafientar, who spent the first, shorter part of his physics career discovering the uncertainty principle under the name of the Indeterminacy Barrier, and then spent the rather longer rest of his physics career trying unsuccessfully to find some way, any way, to work around the blasted thing.)

…is a bugger, as we know, and magical Heisenberg Compensators are a little too handwavy for my taste, thanks so much.  And secondly, even if you only do it at the molecular level, all that binding energy has to go to/come from somewhere in a very short time, and that poses some thermodynamic problems at the level of physics, and some literary/worldbuilding problems in explaining the implications that the ability to routinely toss that much energy about has on everything else.

These may theoretically exist in the future – given that the basis of the emerging field of ontological engineering is to use manipulations of the laws of the laws of physics that underlie the regular laws of physics to tell the latter to shut up and sit down, but they don’t at any part of the timeline I’m working with.