The youngest member of the physics department is normally given the task to answer persons like that, and the best strategy is to write them that you know of one person that is an expert in this field and then forward the letter to another one in the crackpot list.
http://math.ucr.edu/home/baez/crackpot.html
Of course, the youngest member is always going to be the most energetic and unexperienced, and still scalp deep in the prevailing ideology. Having physicists call anyone else a crackpot? They're drawing on a weak hand. :^)