For the first time in its life, the universe will be permanent and unchanging. Entropy finally stops increasing because the cosmos cannot get any more disordered. Nothing happens, and it keeps not happening, forever. It’s what’s known as the heat-death of the universe. An era when the cosmos will remain vast and cold and desolate for the rest of time … the arrow of time has simply ceased to exist. It’s an inescapable fact of the universe written into the fundamental laws of physics, the entire cosmos will die.

Brian Cox