Yes the title is a little bit ambiguous. I wanted to know a few stuff in writing articles and doing research in maths and physics, assuming your work will depend somehow on others work, I guess not every researcher who relies on others work understand their work completely. For example, a work in physics which relies on new machinery in maths, I guess that not all of the theoretical physicists understand the maths they are using, as in rigorously proving it for themselves. What I am getting at I guess is that when you are relying on some established mathematical and physical results which do relate to your work but not directly, I mean your'e using them, but not necessarily need to know why they are correct? is this legitimate for a lot of researchers? A concrete example is for example using random matrix theory in modelling something in quantum cosmology, though you don't necessarily a specialist in random matrix or cosmology (but at least in one of them you are), do you need to know a lot in the other branch? Or the bare minimum? would you need to rely on faith on some results in cosmology if your'e not a cosmologist or results in random matrix if your'e not an expert in it? It's kinda ruining the whole idea of people who try to understand if you need to rely on faith, understanding goes through the window... I guess this is kinda of the bad side for specilization in science.