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.