What is the name of this science fiction book?

I usually don’t like to ask “what is the name of this…” questions, but here’s one anyway.

Sometime in middle school, I read a science fiction book that revolved around some sort of secret society that could control the laws of physics. A kid found one of the books written by this secret society that allowed him to change gravity. He and some of his friends had to use the various laws of physics to prevent some other person (who could also modify the laws of physics) from gaining access to that book and, I guess, take over the world.

Also, there is a person from the book that is somehow an omniscient narrator that later becomes an actual character in the story.

I can’t really remember much more, except for some tiny details that probably won’t help.

Any ideas as to what the name of the book is?