Multiverses are everywhere. Or at least the theory is. Everyone from physicists Stephen Hawking and Brian Greene to Marvel superheroes have shown their support for the idea. But critics argue that not only is the multiverse improbable, it is also fantasy and fundamentally unscientific as the theory can never be tested - a requirement that has defined science from its outset.
Should we reject the grand claims and leave multiverse theories to the pages of comic books? Are tales of the multiverse really sticking-plaster solutions for Big Bang theory in trouble? Or should we take multiverse theory as seriously as its proponents, and accept that modern science has moved beyond the bounds of experiment and into that of imagination?