What proof is there that the universe is discrete and what proof is there that the universe is continuous?
You can never know if the universe is discrete for certain since even if it appears so there may still be some undetectable phenomena you are unaware of.
You can never find evidence to suggest the universe is continuous as there can never be a scientific instrument capable of infinite accuracy.
#23 (skidoo!), those are good points, but they don't lead where you intimate.
The great thing about proposals like relativity was that practical experiments could at least be proposed for them. Being practical, they could be, and WERE, carried out.
String theory is just a set of mathematical games that don't produce results that we can put to the test. It really doesn't get any simpler than that. Hence, string theory is at least highly suspicious as a means for determining the model of reality. We may as well just say "GINSE[*] did it" and let all complexities become encapsulated within that explanation (kind of like rolling up many dimensions inside a string, eh?).
As regards recent physics, string theory is the crown jewel in a large ornament of useless results. "Nuclear stuff and quantum physics" at least give us answers that guide engineering applications. Even the second tier applications (physics-industry-applicable only) at least produces results that can be used to accomplish a physical act. The "huge effect" you note, however, is the result of using radiation, and radiation has been well enough understood for generations to supply such a usage. Past that point ... physics has been stagnant. This stagnancy revolves around the current infatuation with physically-unprovable mathematical exercises!
We need to BEND METAL! We need to MANIPULATE INDIVIDUAL ATOMS! We need to BREAK OPEN NUCLEI! We need to do all that nasty stuff instead of playing math games.
We understand thermodynamics, yet can't seem to deliver ecologically sustainable energy systems to the public. Talk about a "huge effect" -- a huge NEGATIVE effect, that is.
Engineering is very accomplished across the world, but in the First World, where the huge infrastructure exists to further probe reality, we're lost in math games.