The end of the world as we know it

[OngBonga]

Ok, everything with mass interacts with everything else with mass. That much I determine by assuming gravity has negligible, but not zero, influence at great distances.

I'm going to make a leap of faith that everything has mass. That's something I don't doubt you'll take issue with.

[MadMojoMonkey]

Ok, everything with mass interacts with everything else with mass. That much I determine by assuming gravity has negligible, but not zero, influence at great distances.

Yes. The influence diminishes proportional to the square of the distance. M/x^2 != 0 at any finite distance for any non-0 M.

I'm going to make a leap of faith that everything has mass. That's something I don't doubt you'll take issue with.

Well, you can't have both, I think, to resolve your question.

Your prior statement cutely discounted my assertion by noting that neutrinos have tiny, but non-o mass, whereas photons have (as best we can tell) 0 mass. It's impossible to prove a zero in this case, but we've got the photon mass down to definitely less than 10^-50 g. That's roughly 17 orders of magnitude less massive than a neutrino, which is the lightest "massive" particle.

I'm willing to let it wash on all other particles, though. Photon is only one that I know of.