The essay seems to be predicated on the mistaken notion at the time that the electron has no mass (the proton had not been discovered yet). Of course today philosophers of physics might make similar arguments using gluons; see that other hot thread
https://news.ycombinator.com/item?id=35432918RIP M Poincare was a great man.
amts|2 years ago
Have you ever observed that an insulated copper conductor or a diode constantly conducting electrons in one direction would loose mass?