The eternal inflation hypothesis is one of several proposed explanations for the origin of the Big Bang, but it is important to note that there is currently no definitive consensus on why the Big Bang occurred. The Big Bang theory itself describes the rapid expansion and subsequent evolution of our observable universe from a highly dense and hot state.
Eternal inflation is a concept derived from inflationary cosmology, which suggests that the universe underwent a period of extremely rapid expansion shortly after the Big Bang. According to eternal inflation, this inflationary process might not have ceased in some regions of space, leading to the existence of multiple "bubble" universes within a larger multiverse. These universes could have different physical properties and even different laws of physics.
While the eternal inflation hypothesis provides a framework for understanding the possibility of a multiverse, it does not provide a definitive answer as to why the Big Bang occurred or what caused it. It is still an active area of research, and scientists are exploring various ideas and models to better understand the origins of the universe.
Other hypotheses and models, such as the cyclic model and string theory, also offer alternative explanations for the Big Bang. Each of these hypotheses has its own strengths, limitations, and areas of active research. It is an ongoing scientific endeavor to gather observational evidence and develop theories that can provide a more comprehensive understanding of the origins of the universe.