Determining whether our observable universe is part of a larger universe is a challenging question that is still actively explored by cosmologists and physicists. While we cannot definitively prove or disprove the existence of a larger universe beyond our observable boundaries, there are several lines of evidence and theoretical considerations that shed light on this topic. Here are a few points to consider:
Cosmological Principle: The Cosmological Principle is a fundamental assumption in cosmology that suggests the universe is homogeneous and isotropic on large scales. This principle implies that, on average, the properties of the universe are the same in all directions and at every location. If the Cosmological Principle holds, it suggests that the universe is likely infinite or extends beyond our observable boundaries.
Cosmic Microwave Background (CMB): The Cosmic Microwave Background radiation is the residual glow from the early stages of the universe, and it provides valuable insights into its large-scale structure. Detailed measurements of the CMB reveal a remarkably uniform distribution of temperature fluctuations on large scales, consistent with the predictions of an infinite or very large universe.
Flatness of the Universe: Observations and measurements indicate that our universe is very close to being geometrically "flat." Inflationary cosmology, a widely accepted theory, explains this flatness as a consequence of rapid expansion in the early universe. If the universe is flat and extends infinitely, it suggests that it could be part of a larger, unbounded structure.
Cosmic Inflation: The theory of cosmic inflation proposes that the early universe underwent a phase of rapid expansion, which smoothed out its properties and set the stage for the large-scale structures we observe today. Inflation suggests that our observable universe is just a tiny "patch" within a much larger, possibly infinite, multiverse.
Gravitational Lensing: The phenomenon of gravitational lensing occurs when the path of light from distant objects is bent by the gravitational pull of massive structures. The observed patterns of gravitational lensing provide evidence for the existence of large-scale structures, such as galaxy clusters, beyond our observable universe.
It's important to note that while these points provide intriguing hints and theoretical possibilities, conclusive evidence for the existence of a larger universe is still lacking. Further exploration and advancements in observational techniques, such as studying the properties of the CMB in more detail or detecting the imprints of other universes in the cosmic fabric, may contribute to our understanding in the future.