Science Fiction Books

My dad read this book when he was in high school and said it was the best book he’s ever read, but can’t remember the name of.

My boyfriend has already written a science fiction book and is attempting to publish it. I’ve seen some places that state a literary agent is necessary on many occasions or the publisher won’t even look at it. Is this true? If not how do you know which publisher to go to? Any recommendations or advice for a young first time science fiction writer?