Miriam Frankel explores the multiverse with physicists Andrew Pontzen, Katie Mack and Sabine Hossenfelder, in FQxI's podcast series produced by The Conversation. The Many Worlds interpretation of quantum mechanics posits one type multiverse of parallel universes, while some cosmological models suggest others. But is the idea of a multiverse even scientific? Miriam discusses attempts to find evidence of neighbouring universes in the relic radiation of the big bang–and also the criticism that ultimately the idea of a multiverse is not testable and thus not scientific. And could we even make a universe in the lab?