There are plenty of unexplored things in physics too; the key word is "respectable". Looking from the outside, physics suffers a lot from fashion/hot trend ten

There are plenty of unexplored things in physics too; the key word is "respectable". Looking from the outside, physics suffers a lot from fashion/hot trend tendencies, where you need to be doing the "hot" thing to make the jumps necessary to the coveted Tenure Track — and otherwise, you get kicked out.