[FOM] Apartness topology and (constructive) nonstandard analysis

[katzmik at macs.biu.ac.il]

Thanks very much for this.  This was indeed my point.  Cauchy used
infinitesimals (in an essential way) in defining with continuity, in dealing
with convergence of series of functions, in geometric probability, and in the
theory of elasticity. It would be interesting to trace their use in
hydrodynamics as far back as possible, also.  Who was at the origin of this? 
MK

On Wed, September 9, 2015 11:47, S. S. Kutateladze wrote:
> Dear Mikhail,
>
> I've heard this argument about ultrafilters many from those mathematicians who
> think that they are physicists as well, but the real physicists   are ignorant
> of ultrafilters and use infinitesimals when this is relevant, in hydrodynamics
> for instance.