The universe is a physical thing. It is impossible for something physical to be infinite, since matter is finite by its very nature, and no amount of finite things combined can ever become infinite.

Galileo And Freedom Of Thought by Sherwood Taylor pg 34.

" The earliest critics of the ancient astronomy had no better grounds for their criticism( of fixed E) than had Aristotle for his assertions. Their predilection for an infinite universe & moving E was mystical, not scientific. Thus that remarkable man Nicolas of Cusa in 1440 wrote a work entitled Learned Ignorance in which he maintains that E cannot be the centre of U because U is infinite: & since E was not the centre, there is no reason to suppose it to be immobile. 

Pope Eugenius IV raised no objection to the theories of Nicolas & indeed raised him to the purple after their publication. "