Specifically in relation to this theory of ruliads and Hossenfelder's take, one "pop" mathematical concept that comes to mind is Godel's incompleteness theorem.

Specifically in relation to this theory of ruliads and Hossenfelder's take, one "pop" mathematical concept that comes to mind is Godel's incompleteness theorem. It may indeed be mathematically feasible that some holy grail equation exists within the ruliad given that Godel et al have shown that it is possible to just keep recursively describing internally consistent algebraic systems and meta algebraic systems ad infinitum, and that in an infinitely arbitrary meta mathematical system you could describe anything that is "true". It does not, however, follow that such an all-encompassing system physically exists, or that it is finite in some observably interesting way. I.e. the universe could just be infinite in every one of infinite aspects, in a monkeys-and-typewriters sort of way, and that would mean our existence would just necessarily be real, which is just not a very interesting conclusion. Or it could be that the universe is finite/limited in some way that the meta mathematical framework does not predict. And that's where Hossenfelder's take comes in: we don't know that physics is as infinitely big as mathematics, and for the purposes of advancing the field of physics, one needs to work on increasing the confidence of what we do know, rather than saying that what we might eventually know happens to exist within some theoretically infinite set.