The mechanics of engines was understood at the beginning of the Industrial Revolution, and they were fully reproducible: all of which is true of LLMs today. An LLM is a bunch of floating point numbers and simple operations on them, all of which are fully known.

But the way that steam engines emergently transformed heat into work was not understood at the beginning of the Industrial Revolution. Figuring this out led to an entire new branch of physics, thermodynamics. Figuring out how big next-token predictors give rise to interesting systems is likely to lead to similarly new ideas.