Opinion: Great Mysteries of Physics 3 - is there a multiverse?

Prof Andrew Pontzen In The Conversation's Podcast "Great Mysteries of Physics," Professor Andrew Pontzen (UCL Physics & Astronomy) describes the hypothesized concept of the multiverse, a theory that there are infinite possible universes but we only experience a single version of events. Interest in the multiverse theory, suggesting that our universe is just one of many, spiked following the release of the movie Everything Everywhere All At Once. The film follows Evelyn Wang on her journey to connect with versions of herself in parallel universes to ultimately stop the destruction of the multiverse. The multiverse idea has long been an inspiration for science fiction writers. But does it have any basis in science? And if so, is it a concept we could ever test experimentally? That's the topic of the third episode of our podcast Great Mysteries of Physics - hosted by me, Miriam Frankel, science editor at The Conversation, and supported by FQxI, the Foundational Questions Institute. "One way to think of a multiverse is just to say: 'Well, the universe might be really, really big - much bigger than our observable universe - and so there could be other regions of the universe that are far beyond our horizon that have different things happening in them'," explains Katie Mack, Hawking chair in cosmology and science communication at the Perimeter Institute for Theoretical Physics in Canada. "And I think that idea is totally well accepted in cosmology." The idea that there could be other parts of the cosmos with different physical laws, processes and histories is hard to ignore.