I probably won't get to see "Secret History" until next week, since NBC.com is locking new episodes for a week for some reason even though it didn't do that with most of season 1, or with other current shows. But I'm confused by the episode description I read: "At Princeton University in 1955, Ben must find a formula hidden by Albert Einstein that holds the key to nuclear energy before the Nazis get it."
First off, why are Nazis an issue in 1955? Second, the Einstein formula that holds the key to nuclear energy is E=mc^2, and that was published in 1905. And the US government declassified nuclear power technology in 1954. So either that description is seriously in error, or the show's anachronisms and research failures have gotten worse than ever.
Also, I see on the Wiki that Ben leaps into "Professor Henry McCoy." He's Beast?
You're asking questions before watching the episode? As the window washer said: "All will be made clear." Just to answer one of your questions. It's a different formula other than the one we're all familiar with. Einstein kept it secret because he thought this was something mankind wasn't ready for. (I've long heard that Einstein did come up with something that he kept to himself for that very reason, but now think that unlikely because anything he could have come up with someone else would have figured out by now.)