How smart are quantum physicists and are their theories of multi-universes able to be understood by the layman..like me?

I was reading about Hawkings and others Theories of “everything” and was curious how mathematically centric they were. The individuals presenting their arguments seem to spout off string theory, alternate universes and wave mechanics which I could not fully grasp. I was wondering then, who are they actually doing this research for as they seem to be operating on a different plane. or perhaps a good book explaining it simply is in order…