> My current set of candidate pet theories are all based on a vaguely similar foundational notion that the physical universe isn't made up of "matter on top space-time", but rather that there is a single space-time-matter fabric.
> For example, to create matter, space-time must be affected (curved). Or to put it another way, all particles have mass-energy (spacetime curvature) because they are space-time-matter curvature. The idea is to unify QM and GR by making fundamental particles have geometric properties that satisfy GR at all scales.
I also think this is the "obvious solution". Came to the same mental picture of "space-time-energy quants" long ago.
But I guess the main problem is to formulate this in a meaningful mathematical way. (Physics always needs some "stage" on that "things" can happen. GR did not change that; it made the "stage" just more dynamic, and alone that proved to be very hard to formulate in math, which is all about static relations between objects).
BTW: Something that I found very inspirational, and what makes very much sense to me, was this here:
http://www.platonia.com/research.html
(Mr. Barbour has also some pop-science books on his topics).
The basic idea is that there is nothing besides pure geometry on the fundamental level.
That makes sense because to me as what else could be there at all? Anything that is needs to come form somewhere. Only pure structure, something that "just happens" given the idea of "things in a space" could imho resolve this problem. (Which is also quite in line with Wolframs ideas, btw).
That leads to the idea that things "are" because they "must be" alone from the fact that you try to describe their relations.
Contrary to that all physics concentrate on things that aren't "pure". Almost everything in physics is "afflicted" by some "units". But how do you explain the "units"? You can't! They're a given. So imho, even the smallest set of them can't be fundamental. Only pure "proportions", from which "structures" and "shapes" emerge, make sense on the fundamental level. Because such structures "just are", as they're mathematical objects. (Mathematical objects and structure "exist" without being created; nor they can be ever changed or destructed. That makes "very good material" for the fundamentals of a universe, imho).
Also this way to look at things explains one of the most weird and quasi not understood parts of our world, namely time.
Time is a big mystery. Mr. Barbour's ideas were to me the first explanation ever that didn't produce more questions than answers.