The concept of what lies beyond our observable universe is still a topic of active scientific investigation and speculation. Our observable universe is defined by the portion of the universe from which light has had enough time to reach us since the Big Bang, given the finite speed of light. However, it is important to note that the observable universe is not necessarily the entirety of the universe itself.
According to our current understanding, the universe may be much larger than the observable universe. There are a few possible explanations for what might lie beyond our observable universe:
Inflationary cosmology: Inflation is a theory that suggests the universe underwent a rapid expansion in the very early moments after the Big Bang. If inflation occurred, it would have caused regions of space to move apart from each other so rapidly that they are now beyond our observable horizon. This would mean that there could be other regions of the universe, similar to ours, beyond what we can currently observe.
Multiverse theories: Some theories propose the existence of a multiverse, which would encompass a vast ensemble of universes with different physical properties. In this view, our observable universe would be just one "bubble" within a larger multiverse. Each bubble universe could have its own laws of physics and potentially different dimensions, making it difficult or impossible for us to observe or interact with other universes.
Beyond the concept of space: It's also possible that the question of what lies beyond our observable universe doesn't have a well-defined answer within the framework of our current understanding. Our understanding of space, time, and the nature of the universe might break down or undergo fundamental changes beyond our observable horizon.
It's important to emphasize that these ideas are still speculative, and further research and observational evidence are needed to provide more conclusive answers. Exploring the nature of the universe beyond our observable horizon is a fascinating area of study in cosmology, and ongoing research continues to push the boundaries of our understanding.