The Big Bounce is a theory about the ultimate fate of the universe. According to this theory, the universe has gone through cycles of expansion and contraction throughout its history, and will continue to do so into the future. This means that the universe could potentially "bounce" back in on itself, leading to a new Big Bang and the creation of a new universe.
The idea of the Big Bounce is based on the concept of cosmic inflation, which suggests that the expansion of the universe could be driven by a field of energy that is present throughout the universe. This field could eventually cause the universe to contract, leading to a collapse and a new Big Bang.
It's important to note that the Big Bounce is just a theory and that we do not yet have a definitive answer about the ultimate fate of the universe. Other theories, such as the Big Freeze and the Big Crunch, also propose different scenarios for the end of the universe.