the observable universe is expanding.
when they say it is expanding they mean that the distance between galaxies is growing bigger over time, ever since the big bang matter has just been getting further and further apart from each other.
which in fact suggests we live in an infinite universe. otherwise the matter would have hit an "edge" and bounced back inwards. The fact it did not bounce back indicates an infinite universe. which means the observable universe (matter and light) is ever expanding until the heat death of the universe
what do you mean by support? are you referring to simulation theory?
the universe is by all observations an infinite emptiness that is being filled by the staggeringly massive quantity of matter and energy from the big bang.
but while staggering, the quantity is finite. spread said finite quantity across an infinite vastness of space and you get heat death.