Can we talk about how to respond to conspiracy theorists who start asking about chemtrails in class?

I had a student ask about this in the middle of lecture, and although I could attack the idea of it from the ground up, I was totally unprepared, and probably came off as a bit of a nut--or at least someone who has far more trust in the state than I actually do. I guess the problems are in the nature of conspiracy theories themselves--they are necessarily vague, secretive, impossible to articulate fully, and thus impossible to really squash. Plus, with chemtrails specifically, they're so preposterous based more on the context of our government, economy, and so on, but how do you explain context succinctly?

I went through the book list and found Braudel's "The Mediterranean in Times of Phillip the Second". It says there that this book is "Possibly the most important work of history of the 20th century"

I've already got a copy of the book, but before I start with it, I'd like to have a rough idea of what makes this book so important. How did this book impact the way history is written? Do I need to read something else before to understand the impact of this book?

I am not really sure if these questions are appropriate for this thread. If they aren't please let me know.

A reminder that the latest thread for our hot new fan-created fan-favorite feature "The Indiana Jones Game" is still open!