First you guess. Don't laugh, this is the most important step. Then you compute the consequences. Compare the consequences to experience. If it disagrees with experience, the guess is wrong. In that simple statement is the key to science. It doesn't matter how beautiful your guess is or how smart you are or what your name is. If it disagrees with experience, it's wrong. That's all there is to it.
Richard P. FeynmanI learned from her that every woman is worried about her looks, no matter how beautiful she is.
Richard P. FeynmanAll theoretical chemistry is really physics; and all theoretical chemists know it.
Richard P. Feynman