Have you ever considered the second law of thermodynamics? If areas with a high concentration of energy, of chaos, are constantly moving toward areas of low concentration, eventually there will be an equilibrium. The universe is constantly moving towards a state of ultimate chaos and disorder. A homogenous mixture of all matter and energy in the universe, and there won't be anywhere for the energy to move to. No physical processes will ever be able to happen because there won't be any areas of lower concentration for any energy to move to. All stars will have burned out long before this time, as they are attempting to push their energy into empty space where there is no energy already. The dying of a star is basically the star's energy finally completing its goal of stretching to everywhere. When the last star dies, it will only have done so because all other stars and matter and energy will have already been evenly dispersed throughout all the rest of space and time. The universe will be dead.