Hey all Lets say one has a PhD in physics. This person's research interests include solid-state physics. Is it true then, that this person will be totally clueless in string theory and other theoretical stuff? So he has to learn the material from scratch? Same lets say with a PhD in math. If this person's research interests is in algebraic topology, then will he totally be clueless about probability and statistics? I have noticed here on the forums, that the pure math individuals do not really answer probability and statistics questions. Why is this?