Oh man, after a few encounters they'd deliberately attend each other's talks/demonstrations to ask horrible questions. Oppenheimer would throw around Sanskrit quotations so he could feel smug when Howard didn't understand them. Howard would then possibly learn Sanskrit just to be able to retort the next time it happened. It wouldn't help that there was only about an hour's distance between their respective homes so distance would be no barrier to perpetuating the grudge, and given how many ex-Manhattan Project scientists ended up settling in Princeton, I wonder if third parties would get pulled in very often. It could turn even messier very fast. It would definitely end up going down as an academic rivalry for the ages. I imagine there would be lots of historical analysis by third parties about what, exactly, Oppenheimer was referring to when he accused Stark of being a fraud. Yeah, that could be really fun. (Now if only I could figure out a way to convincingly drag Einstein into the middle of one of these spats, but it doesn't seem like him.)