Artist's idea of the Earth several billion years from now, when the Sun is a red giant.
The ultimate fate of our universe may be the heat death of the universe or the big rip. Before that happens, it is possible to predict that the following will happen.
Some types of science can say what could happen far into the future. It is worth noting that our local group of galaxies are bound by gravitation, and its changes and aging can be discussed separate from the rest of the universe.