[camacazio]

You seem to still be having trouble with the idea that if m*a=n*g*m, then m cancels and all we care about is accelleration a. it doesn't matter if m is a million times larger or a thousand times smaller, it's the same accelleration. I use friction for the original idea of modeling a time delay caused by it in expansion, but if it's really causing you that much trouble then let's just use some accelleration a. We're not dealing with force, we're dealing with linear one dimensional uniform accelleration. To reiterate the equation of velocity for that, it's v(t)=v0-a*t. Mass doesn't come up. You can replace each ng I used with a, and everything's fine for rates of expansion.

Changing mass is not a consequence of lorentz contraction. That is incorrect. The only thing that is a consequence of lorentz contraction is lorentz contraction. Lorentz contraction is a consequence of changing time intervals between events used to measure a length. The same rest mass is squished into less volume, so one could argue that density is increased, but this says nothing about mass. These are things that do not matter with regards to mass. This relavistic mass you keep bringing up is a consequence of kinetic energy. Something moving near the speed of light has it's rest mass, E=mc^2, added to it's kinetic energy. The total energy is gamma*mc^2. Momentum, equally important, relativistically is gamma*mv. The m in those cases is the same rest mass used with equations involving a factor of gamma. Rest mass is a poor term because the gamma does not come from mass, it comes from the proper time. "Relatavistic mass" has a factor of gamma not because of mass but because of velocity. Velocity is defined as dx/d(tau), tau being the proper time. Tau=t/gamma. When you make the change of variables, you have gamma*dx/dt. That's the very simple way the equation for momentum appears.