We don't know with certainty how the universe will change in the future, however we do have a decent understanding of how the universe works at a large scale.

We don't know with certainty how the universe will change in the future, however we do have a decent understanding of how the universe works at a large scale. We can use that understanding to make hypothesis that are backed by both data and theory. This is one such hypothesis. This is part of the scientific method. In astrophysics data is collected and new experiments are done to improve theory, and it helps us better understand the history of the universe and the future of the universe. Our understanding will change over time.