Life expands into the universe, which is open. As the universe cools, life stores energy to survive (do information processing). It waits until the universe is cool enough, performs some processing with part of its energy stores, then waits until the universe has cooled so much that the remaining energy can be used to do an equal amount of computation, and so on. Essentially life has to adapt as the universe grows older, changing itself to be able to survive when the stars grow cold. If the universe is open, there will be plenty of time to work in, but energy will become very scarce. Dyson has shown that a finite amount of energy is enough to guarantee infinite survival if it is spent sufficiently slowly.