The observable universe refers to the portion of the universe that we can currently observe from Earth. It is limited by the distance that light has had the time to travel since the Big Bang, which is approximately 13.8 billion light-years. Beyond this observable universe, there may exist regions that we cannot directly observe.
However, it's important to note that the concept of the observable universe does not imply that there is nothing beyond it. In fact, it is widely believed that the universe extends far beyond what we can currently observe. The universe may be much larger than the observable universe, potentially infinite in size.
While we cannot directly observe these distant regions beyond our observable universe, scientists make use of various methods and theories to infer their existence. One such concept is cosmic inflation, which suggests that the universe underwent a rapid expansion shortly after the Big Bang. This inflationary period would have allowed regions that are now beyond our observable universe to have been in closer proximity to us in the past, thus leaving an imprint on the cosmic microwave background radiation that we observe today.
Additionally, scientists use mathematical models and observations of large-scale structures in the universe to study its overall properties. By analyzing the distribution of galaxies, the clustering of matter, and the patterns in the cosmic microwave background, they can gain insights into the composition and structure of the universe on scales larger than our observable universe.
While we may not have direct information about what lies beyond our observable universe, ongoing research and advancements in observational techniques and theoretical models continue to deepen our understanding of the cosmos.