I was surprised when I heard Tristan Buckmaster, an expert on fluid dynamics, say that we still don't understand basic things from first principles like how airplane wings generate lift.

https://youtu.be/PQYFRuZ5phs?si=wy8-ksarC1pVgQuT&t=5235

I suspect we're always going to be in this state because every new breakthrough in engineering raises new fundamental questions.