I had the fortune of taking Erdmann's Python class at the University of Arizona 15 years ago --- a Python/Pylab/data engineering class aimed at materials science engineering students.
He was already getting into this kind of art spectroscopy at the time, and the things he'd showed us at the time that they'd already discovered were wild. IIRC, they had laid out many Rembrandts on the same large "scroll" of canvas, identified where they were painted relative to one another on the scroll, and even identified some paintings of unclear authorship by thing them to that same scroll.
It was not at all surprising to see him move to Amsterdam and keep working with the Rijksmuseum. I smile every time I see this work pop up.
[1] https://www.youtube.com/watch?v=z_hm5oX7ZlE