This illustration shows three possible futures for the Universe, depending on the behavior of dark energy, by showing how the scale of the Universe may change with time. If dark energy is constant, as the new Chandra results suggest, the expansion should continue accelerating forever. If dark energy increases, the acceleration may happen so quickly that galaxies, stars, and eventually atoms will be torn apart, in the so-called Big Rip. Dark energy may also lead to a recollapse of the Universe, in the Big Crunch. The illustration also shows the early decelerating expansion of the Universe, followed by the accelerating phase that started about 6 billion years ago. (Credit: NASA/CXC/M.Weiss)
