What do scientists not know?

Answer 1

a. Generally

Who THEY are. That is a fundamental insight in western perspective. The West (Occident) is mainly interested to OBSERVE, measure and describe objects and occurring phenomena. Western perception is going to look on the outside world.
Nut what is with the OBSERVER? Buddha for instance is interested not preliminary in the outside (he called it maya, illusion) but in the observer himself, he wants to look inside.
So, looking outside is different from looking inside. Is there a correspondence? What has an outside observation to do with the observer? Do you see the difference? proof for yourself: ask severely WHO YOU ARE! I bet you are unable to say it. It needs strange ways to find parts of an answer simply to experience afterwards you failed again.
Here is a reason why brilliant scientists can be pricks inside and price winner outside.

b. frontiers of knowing

We don't know much about what knowledge is, what perception, short, what our brain is, how it works etc. As a thing it is bound in space and time - it is limited. Transcending limits is a good question, how and when that goes. Who knows?

c. hidden processes

What was it like before big bang /creation? Some processes lay behind horizons and stay hidden forever, i.e. inside a black hole, inside a proton etc pp. Such an horizon is called Ereignishorizont (german). These are frontiers of knowledge.