Transcript: In standard big bang models the curvature of the universe and its fate are related. In a high density universe where the density of matter exceeds the critical density, the universe will reach a maximum size and then re-collapse. The strong force of gravity causes the expansion to be overcome. The result is a reversal of the big bang called the big crunch. Our universe appears to have insufficient matter to match the critical density and so will likely expand forever. Extra evidence for this is the existence of vacuum energy or cosmological constant. The fate of our universe is therefore going to be the big chill. In this outcome, the cycle of star birth and death eventually is broken within galaxies as all the gas is used up. After about ten to the thirteen years, ten trillion years, most of galaxies will just contain white dwarfs, black holes, and other dark or dim stellar remnants. Galaxies essentially will switch off slowly with time. After ten to the thirty-five years fundamental particles will decay, and after ten to the power eighty years, although the number is uncertain, black holes within galaxies, even at their nuclei, will evaporate. The eventual result is a uniform sea of electrons, positrons, neutrinos, and low energy photons.