Scale Invariance as an Alternative to Dark Matter and Dark Energy
sciencedaily.comI would like to know what scale invariance is. The abstract doesn’t describe it, can anyone point to a good summary?
Wikipedia's page looks to be solid at first glance: https://en.wikipedia.org/wiki/Scale_invariance
LMWTFY. Actually, I had read this and it wasn't helpful. There is nothing about how x -> lamba x passes through field equations for example, and yields an additional term that represents additional expansionary acceleration. Only the abstract from the paper is available in the OP link, I was wondering if anyone had insight into how these findings came about, generally.
So what future testable predictions does this theory make? Explaining existing phenomena is not enough for good scientific theory.
Dark matter makes the prediction that there is some kind of matter which makes no or little interaction with ordinary matter. None of those has been found so far. This makes it an assumption.
This theory makes no such assumption. One could say that it is simpler so it would fit Occams razor. Even further, it predicts that you can't find dark matter at all (although this can't be proven, so there's that) as much as special relativity predicts that you can't find "aether".
I think, "simpler" would be compelling enough, but I can't judge whether it is the case really.
On another note, does anybody know whether "inflation" makes testable predictions? From my little knowledge it also explains only already known phenomena. Nevertheless it is a widely accepted theory.
This is incorrect. Scientific theories explain observed phenomena, and must be falsifiable, testable, and tested against the best available observations. However there is no requirement that these observations happen in the future. Evolution is a good counter example to your assumption. Anyway, in cosmology we can't wait for the future, its too far away.