Variable light speed and speical relativity

[Mr. Burns]

I was reading about the VSL theory as an alternative solution to inflation that solves the horizon problem. My question is, wouldn't special relativity still hold true, just to a different value of c in the early universe? As in, if we have a varying value of c, wouldn't it still hold true that mass would increase as it neared c?

[Drakkith]

I don't know for sure but that sounds correct.

[Chalnoth]

I was reading about the VSL theory as an alternative solution to inflation that solves the horizon problem. My question is, wouldn't special relativity still hold true, just to a different value of c in the early universe? As in, if we have a varying value of c, wouldn't it still hold true that mass would increase as it neared c?
From what I've been able to gather, the people who were working on this a few years back largely just lost interest in it, as it didn't seem that likely, so the idea was never fully-developed. One of the main difficulties with this sort of model is that it is very difficult to produce reheating.

[skydivephil]

Did it (VSL theory) ever make any predictions? Did it also explain the relic particle problem or the flatness problem?

[Mr. Burns]

Not particularly. It seems to me that it was a way to solve the horizon problem, and had a few party tricks (such as a way to explain the creation of all matter by violating the law of conservation of matter), but was just another, "this seems reasonable, let's follow it" kind of theory. But my question still is, assuming that light traveled faster, as fast in the kaluza-klein 4th spatial demention, why wouldn't relativity hold? C is different, yes, but if einstein was right, it would still limit how fast matter would travel.

[Chronos]

I'm unaware of any observational signatures supporting the idea.