It makes sense to think in terms of three levels of knowledge about a field:
- Knowing what a field is about—knowing what sorts of physical systems and phenomena it deals with, and what sorts of questions it asks and answers.
- Knowing the content of a field in a qualitative sense—having a good feel for what sorts of phenomena can be important in what circumstances, and knowing when you need answers from work in that field.
- Knowing how to get those answers yourself, based on personal mastery of enough of the field's subject matter.
If one has enough knowledge at levels (1) and (2) in enough fields, then one can steer clear of problems in those fields while doing work in a related field where you have knowledge at level (3). And this is a good thing, because knowledge at levels (1) and (2) takes far less time to acquire. But to make proper use of knowledge at levels (1) and (2) requires a harsh discipline: attempt to assume the worst about what you don't know. Don't assume that a poorly-understood physical effect will somehow save your design; do assume (until finding otherwise) that it may utterly ruin it. Without this discipline, you'll become an intellectual hazard. With it, you'll be able to make a real contribution.