>I wonder if our common expectation that true theories somehow had to be beautiful and elegant is going to survive the coming century.

That's the layman's idea of physics theories. They are beautiful and elegant only on the surface, that's why they're technically models and approximations of the real world. The standard model renormalization techniques are a mess of patches and ad-hoc heuristics, pretty far from the "this lagrangian literally contains all physics". Generally you just _ignore_ higher order terms and just call it a day. The famous E=mc^2 it's just the first term of a Taylor expansion. The beautiful form of physics it's what you would call "good enough" and often just a pedagogical tool.

> The famous E=mc^2 it's just the first term of a Taylor expansion.

Is this actually true? My understanding was that E=mc^2 is exact for a particle at rest.