Dropping out of lurking mode to ask - is the bald guy with a mustache supposed to be a famous historical mathematician or physicist? He's wearing kinda an old-fashioned suit, so that was my first thought.
Maybe it's supposed to be Max Planck? He has the bald head, the mustache, usually wore bow ties for pictures, and was German after all.
Well, the bald head & mustache could also point to Dirac, Sommerfeld, Thompson ...

I don't think it's necessarily meant to be
a specific historical physicist so much as a
type that may have been 'not uncommon' at US physics departments during a short period of time around the end of WW-II - back in the foundational period of quantum theory and relativity, Germany-, and specifically Göttingen, was the Mecca of theoretical physics, and physicists would learn German to be able to be were the music is. Starting in the 1920s/30s, American Unis (particularly MIT) started aggressive hiring practises to attract foreign talent, and with the rise of the Nazis, and later the race between the US and the Soviet union for German engineers and physicists, I guess you got them 'a dime a dozen'.
So there (probably)
was a period when you'd hear a lot of German on US physics campuses (there are some remnants of that in (nominally) English math and physics-jargon, e.g. English-language textbooks talking about
Eigenvalues of linear operators), even from non-German physicists (consider also, that even in Europe, German native speakers aren't necessarily German nationals - Austrians speak German, too, as do a lot of Swiss. And until WW-I, a sizeable share of German-heritage communities in the US offered bilingual German/English education).
Contemporary German physicists rarely wear bow ties and most of us speak pretty decent Inglese (either that, or I missed another memo ...), whatwith English being the current lingua franca in physics.
P.S.: Planck would be a possibility if we purely consider looks, but methinks that'd be a bit ahistoric - firstly, he died in 1947 and never lived in the US, and secondly, old Max had a cold-ass stare that'd make a Borg squirm. Don't think was the type to chat up random barristas. Very Kaiserreich, very Prussian.