Grad school physics was/is your background I assume. I had the same thought when reading.

Yep, I was a graduate student in physics, but not at all in that field. The reason why I recognize Dalibard's name even misspelled is because I was a student in the same institution and I used to know several of his grad students.

Little bit of trivia: he was 23 or 24 when he wrote that paper…