Comment by lutusp
4 days ago
>> Our universe is expanding. It's density is not fixed.
> None of that precludes uniform density at large scales.
According to observation, the universe is expanding. An argument that it's really static at a large scale would require contradicting observational evidence, but none exists. A theory that requires abandoning observational evidence bears a special burden, which this theory lacks.
Black holes are capable of expanding, they do it by eating material from outside.
The universe's expansion, and a black hole's increase in mass over time, are unrelated phenomena. We could have one without the other. In fact, because of Hawking radiation, in the far future we might see a larger universe accompanied by smaller black holes.