In Shutter Island, Teddy Daniels (Leonardo Dicarprio) has a fight with a patient in loose in the ward C. During this fight, the patient says that he will never leave that hospital.
Billings: Listen! I do not want to leave, all right? I mean why wouldn't anyone want that? I have heard many things here. About the outside world. bout atolls, about the hydrogen bomb tests. You know how a hydrogen bomb works?
Teddy: - I know. With Hydrogen. With hydrogen.
Billings - Ah! that's funny. Other bombs explode, right? but not the hydrogen bomb. It implodes.
It implodes creating an explosion to the thousandth, the millionth degree.(in a louder voice and it resounds).
Do you understand?
Teddy: I understand.
Why was Billings talking about the impulsion reaction of a Hydrogen bomb so specifically and what's funny in it? Why was his last sentence given a higher emphasis?