Stephen Hawking had written a final paper before his death, concerning how we might be able to detect parallel universes – and you can read it right now.
A pre-print of the paper titled A Smooth Exit from Eternal Inflation? is available here on arXiv, co-authored with Thomas Hertog from the University of Leuven in Belgium and submitted just two weeks ago. It’s currently being reviewed by a scientific journal ahead of publication.
The paper delves into the idea that we live in a multiverse, with our universe being just one of many. And it suggests that an imprint of other multiverses may be detectable in the background radiation of the universe.
“This is a theory of the Big Bang. It is an improved version of Hawking’s original 'no-boundary’ model of the Big Bang, which he and James Hartle put forward back in 1983,” Hertog said in comments emailed to IFLScience. That theory suggests our universe’s Big Bang was accompanied by the Big Bangs of other universes.
“Gradually we realised the model described not one but infinitely many universes,” said Hertog. “Cosmologists call this a multiverse – an ensemble of universes which exist in parallel.
“Hawking was not satisfied with this state of affairs. 'Let’s try to tame the multiverse', he told me a year ago. So we set out to develop a method to transform the idea of a multiverse into a coherent testable scientific framework.”
According to their paper, it might be possible to detect the remnants of Big Bangs of other universes in gravitational waves emitted from our Big Bang. While the idea of a multiverse is hotly contested, Hawking and Hertog’s model suggests that we can find strong evidence for the existence of other universes in our own.
The paper is still being reviewed, so we can’t analyze it too much yet. But if true, if we could really find evidence of a multiverse, that would be a Nobel Prize-winning discovery.
“In my opinion, Hawking should have been awarded the Nobel prize long ago,” said Hertog.
These included the prediction of Hawking radiation, information that could be emitted by black holes. His book, A Brief History of Time, meanwhile, remains one of the most popular science books of all time. Even after his death, though, he's still making waves in the world of science.
“Stephen was an adventurer and science was his greatest adventure of all,” said Hertog. “This paper is just one example of this.”