The theory proposes that, in each cycle, the universe refills with hot, dense matter and radiation, which begins a period of expansion and cooling like the one of the standard big bang picture. After 14 billion years, the expansion of the universe accelerates, as astronomers have recently observed. After trillions of years, the matter and radiation are almost completely dissipated and the expansion stalls. An energy field that pervades the universe then creates new matter and radiation, which restarts the cycle.