[FOM] R: constructivism and physics

[Todd Wilson]

Antonino Drago wrote:
> Surely since its beginnings theoretical physicists (Cavalieri, Torricelli,
> Newton) made use of infinitesimals, whereas Galilei, Huygens and Leibniz
> resisted to them. Almost two centuries after, rigorous calculus confirmed
> almost all the results obtained by infinitesimals; but not all.

I'm giving an informal talk on infinitesimal analysis at our math 
seminar in a couple of weeks, and I would love to include an example of 
a result obtained by infinitesimals that has not been confirmed by 
"rigorous calculus".  Can you give an example (or, better, a few)?

--
Todd Wilson
Department of Computer Science
California State University, Fresno