Perpetual Universe?

Actually, the current indications are that the universe will continue to expand indefinitely. In fact, the rate of expansion is increasing. The general theory of relativity predicts that he universe could also come to the end of its expansion and collapse on itself eventually. That model does not predict that the expansion will start again with another "big bang", but that concept was suggested. What "causes" it is the nature of the gravitation as described by the general theory of relativity.