An amazing paper by Dan Hooper appeared on the arXiv preprint server in the past week: “Life Versus Dark Energy: How An Advanced Civilization Could Resist the Accelerating Expansion of the Universe”. The idea is that extremely advanced alien civilizations seeking to maximize the energy available to them billions to trillions of years into the future might want to start gathering distant stars and bringing them closer to home. By moving the stars at relativistic velocities, one could prevent them from being carried outside the horizon by the accelerating cosmic expansion due to dark energy. However, since stars of all masses are not equally suitable for this relocation trick, the end product may be large groups or clusters of galaxies with pretty unusual spectral properties.
Link to paper: https://arxiv.org/abs/1806.05203
– Erik Zackrisson