Why is Lagrange buried in the Panthéon in Paris, but not any other French mathematicians or theoretical physicists? I would understand if they were not represented at all, but it seems absurd to choose just one from a selection of many great names.
A definitive list might be useful. I went through the entire list, and here are my results.
Mathematicians and physicists buried in the Panthéon:
Physicist Marie Curie.
Physicist Pierre Curie.
Physicist Jean Baptiste Perrin.
Physicist Paul Langevin.
Mathematician Paul Painlevé. (Also a politician)
Mathematician Lazare Carnot. (Also a politician)
Mathematician Joseph-Louis Lagrange.
Mathematician Marquis de Condorcet. (Also a philosopher). His remains have been lost.
Mathematician Gaspard Monge.
The chemist Marcellin Berthelot. (Also a politician)
The physiologist Pierre Jean George Cabanis. (Also a philosopher)
Physician and scientist (and other things) Jean-Paul Marat. (Later disinterred from the Panthéon)
At this point I have gone through the entire list, every biography at least three times. Several interred have no direct biography, but I chased and read their French biographies in every case. I now believe that this is complete. My inclusions in the "Other Scientists" category were a judgement call. I omitted a couple of physicians and cartographers (and that sort in general) in the spirit of the original post. I would be pleasantly surprised to hear I missed someone.
Visiting the Panthéon biographically was a historically enriching way to spend a Sunday morning for me. I will be sure to take pictures of all of these memorials the next time I find myself in Paris.