The late great cosmologist Stephen Hawking spent his illustrious career battling the most enigmatic and vexing questions in our known universe, such as black holes, quantum mechanics, dark matter, and others. But his final paper took on an even greater challenge--discovering what's outside our universe. Hawking proposed a way to test experimentally for evidence of parallel universes, suggesting we may live in a multiverse in which an infinite number of 'Big Bangs' are expanding and contracting, each with their own natural laws and physics.
The paper, entitled "A Smooth Exit from Eternal Inflation?", co-authored with Thomas Hertog, a professor of theoretical physics at KU Leuven University in Belgium, discusses the use of a deep-space probe on an epic data-collection mission to measure fluctuations in background radiation that might suggest collisions with other universes in the cosmic foam.
"The intriguing idea in Hawking’s paper is that [the multiverse] left its imprint on the background radiation permeating our universe and we could measure it with a detector on a spaceship," professor Carlos Frenk remarked. "These ideas offer the breathtaking prospect of finding evidence for the existence of other universes. This would profoundly change our perception of our place in the cosmos."