Would be interesting to train a cutting edge model with a cut off date of say 1900 and then prompt it about QM and relativity with some added context. If the model comes up with anything even remotely correct it would be quite a strong evidence that LLMs are a path to something bigger if not then I think it is time to go back to the drawing board.
I suppose the vast majority of training data used for cutting edge models was created after 1900.
But considering that Special Relativity was published in 1905 which means all its building blocks were already floating in the ether by 1900 it would be a very interesting experiment to train something on Claude/Gemini scale and then say give in the field equations and ask it to build a theory around them.