On writing characters who are smarter than you are

This comes up a lot in workshops and I want to give it a serious answer because the usual advice ("just fake it") is not helpful. When you write a genius character - a chess grandmaster, a quantum physicist, a criminal mastermind - you are not writing their intelligence. You are writing its effects. The genius sees the board differently. You don't need to understand every move; you need to understand that everyone else is three moves behind and show us that gap. Practical techniques: 1. Research the domain enough to know what the questions are, not necessarily the answers. Your genius character asks better questions than other people. 2. Let the genius be wrong about things outside their domain. Sherlock Holmes is rubbish at normal human interaction. This isn't a weakness in the character - it's what makes the intelligence feel real. 3. Write the other characters's reactions to the genius. We understand that someone is exceptional by watching others fail to keep up. 4. The genius should have a blindspot the reader can see but the character cannot. This is where your story actually lives. What domains have people found hardest to write intelligence in?