I'm not sure if you could find any larger assumptions?
Perhaps baryonic assymetry is only a local feature creating completely different structures in the observable universe. Perhaps past expansion is far accelerated or the acceleration increase and decrease over time. Perhaps "c" is not a constant.
The work of Barrett et al. "Undermining the cosmological principle:[...]" shows that minimal fluctuations in CDM does not necessarily show isotropy and homogeneity.
Add to this that observable matter is postulated to be < 5% of the universe and we don't really have a handle on dark matter. We don't even know for sure how many dimensions there are ... we're pretty clueless really.
Perhaps baryonic assymetry is only a local feature creating completely different structures in the observable universe. Perhaps past expansion is far accelerated or the acceleration increase and decrease over time. Perhaps "c" is not a constant.
The work of Barrett et al. "Undermining the cosmological principle:[...]" shows that minimal fluctuations in CDM does not necessarily show isotropy and homogeneity.
Add to this that observable matter is postulated to be < 5% of the universe and we don't really have a handle on dark matter. We don't even know for sure how many dimensions there are ... we're pretty clueless really.