An eternal infinite in space universe doesn't violate the second law of thermodynamics just as much as animal homeostasis does. It only means that the universe is either a closed or open system, and as far as we know, that is impossible to prove because in mathematics infinity can be a cardinality, or a limit.

A limit would mean that it's an open system, ever-expanding, even though it is infinitely large, while a cardinality would mean that it is closed--yet infinite itself! I tend to think of infinity as a cardinality due to the fact that infinity itself can contain infinity--to infinity... so, the ultimate infinity is the cardinality of the Continuum, or C.