Stephen Hawking was an amazing English physicist. Have you ever heard of him?
I have! I don't know much about him, but I know my son thought he was a genius! 
Yes, he was a genius! He was a cosmologist. One of the things he was known for was his prediction that black holes emit radiation. 
That's an interesting theory! Didn't he have a terrible disease? What disease did he suffer from?
I am not exactly sure, but it might have been ALS. He had such an excellent mind. He supported something called the "many-worlds" interpretation of quantum mechanics, which I think means that he believed there is life beyond earth. 
That's an incredible theory! He amazes me. Where was he from?
He was from England. He taught and conducted research at the University of Cambridge.