It has been the physics community's long-standing dream to unify the natural forces into a single comprehensive theory. Two of the pioneers in unified field theory attempts were physicists Oskar Klein and Albert Einstein. In my new history of physics article, I explore connections between their quests for unification in five dimensions.
Here's a link to my recently published article (subscription required to see the full content; alternatively, paper copies available upon request):
Klein, Einstein and Five-Dimensional Unification