Background radiation is observed in all directions and is very uniform, consistent with there having been a universe which was so hot that it was opaque, that cooled down and liberated the radiation we now observe as background radiation. However, this tells us nothing of how large the universe was at that moment, but only how much energy and mass it had.
Mainstream science accounts for background radiation by demonstrating that if there was a Big Bang, background radiation would inevitably be produced. It has an Occam score of 0000 relative to the Big Bang, and an absolute Occam score of 5000.
QO accounts for background radiation by the same inevitability, but related to the Clump rather than the Big Bang. This account has an Occam score of 0000 relative to the Clump, and an absolute Occam score of 3000. It is therefore to be preferred.