Inflationary theory allows for regions of space to inflate separately, producing “bubble universes.” Each could have different physical constants and properties. While speculative, it offers a framework for understanding fine-tuning in our universe. Observational evidence is indirect, but cosmic microwave background anomalies hint at possible collisions between universes. The idea expands Big Bang theory into a broader cosmic context. It challenges the notion that our universe is the only one.
It matters because the multiverse could explain why physical constants appear finely tuned for life.
It also pushes the boundaries of cosmology, blending physics with philosophical questions.
Our universe may be one bubble among countless others.
Institute for Advanced Study [ias.edu]