> But your claim is a falsehood. I asked you to provide evidence that it doesn't vary and you said you can't but you assume the variance comes solely from the m

> But your claim is a falsehood. I asked you to provide evidence that it doesn't vary and you said you can't but you assume the variance comes solely from the measurement equipment. That's not what "evidence" means. My claim is literally true. No evidence exists that suggests the mass of an electron varies. Feel free to prove me wrong by providing such evidence. All existing measurements of the mass/charge of an electron are consistent. I really don't have the time to look up papers measuring the mass of an electron and figure out what degree of accuracy they're claiming and compare the measurements, but I guarantee you if you bother doing this you'll see the measurements are all the same. > We have variance. Either there's proof that it's the measurement, or there isn't. Assuming is just that. Variance is the expected outcome. Human-made measurement devices are imperfect. If the mass/charge of an electron varies, it either would have to do so at a level where our tools can detect it (provably untrue) or it would do so at a level below where our tools could detect it (unprovable until our tools improve obviously). > I'll tell you another assumption we often take for granted: speed of light. ... The fact we cannot measure the 1-way speed of light is well known. Using 'c' as the speed of light is a common convention. On the other hand, we _can_ measure the mass/charge of an electron, and that value is consistent to the degree we can measure it accurately.