Re: Kryptonite in first film... Extent of use?
I've never really understood the red sun weakness. It's not as if a red sun is the opposite of a yellow one, it's just an older, cooler sun. It shouldn't harm Superman anymore than nighttime.
I said in another thread I'd like to see what else kryptonite can do besides harm Superman. In the comics, it powers Metallo, and gave Conduit and Russian Zod superpowers, and the waste from experimentation on it transformed Rudy Jones into Parasite. Then that was expanded upon in Smallville. I don't really want it implied that kryptonite can just randomly mutate anyone though.
Plus, I'm thinking, considering that it can give humans powers, maybe it relates to Kryptonians and their abilities too. Like an early form of kryptonite existed as part of the planet and gradually evolved Kryptonians into solar batteries, and the destruction of Krypton changed it into something lethal to Kryptonians.
Superman with realistic physics isn't Superman.