Talk of other universes has become fashionable amongst physicists and is popular with the public. But the numbers have become hardly credible: string theory predicts 10^500 parallel universes. Some argue the very idea is nonsensical. Should we recognise ours as the only universe and give up on others as fantasy science? Or is slipping through a worm hole into another universe a credible reality rather than a Hollywood fairytale?
Harvard string theorist Cumrun Vafa, CERN physicist John Ellis, and author of Worlds Without End Mary Jane Rubenstein dispute the possibility of universes outside of our own.