Hawking Publishes Posthumously on Multiverse Theory

Stephen Hawking, the famous Cambridge University physicist who passed away in March, posthumously published today on the possibility that the multiple universes in the cosmos may be more similar than once suspected.

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The work, released in the Journal of High Energy Physics, is a collaboration with Belgian physicist, Thomas Hertog. "We sat on this one for a very long time," Hertog told The Guardian. "I do believe he was really fond of it."

The work, which the two completed weeks before Hawking died, challenges the idea that the multiple universes that have formed over the past 13.8 billion years since the big bang are vastly different.

"The usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes separated by an inflating ocean," Hawking said last autumn.

However, in their co-publication, Hawking and Hertog say that despite being formed amidst radically different laws of physics, the individual universes may not be that different from one another.

"In the old theory there were all sorts of universes: some were empty, others were full of matter, some expanded too fast, others were too short-lived. There was huge variation," said Hertog. "The mystery was why do we live in this special universe where everything is nicely balanced in order for complexity and life to emerge?"

"This paper ... reduces the multiverse down to a more manageable set of universes which all look alike. Stephen would say that, theoretically, it’s almost like the universe had to be like this. It gives us hope that we can arrive at a fully predictive framework of cosmology."

Traveling to Cambridge to work on the paper with Hawking prior to his death, Hertog says, "I always had the impression that he never wanted to quit and, in a way, this was Hawking. He never showed any sign of wanting to quit."

"It was never said between us that this would be the last paper. I personally felt this might be the conclusion of our journey, but I never told him," recounts the Belgian professor at the Catholic University of Leuven.

"Stephen himself said that this work was the area he was most proud of," Malcolm Perry, a colleague of Hawking’s, tells the Guardian.

Hawking will be the co-author of at least two future publications with Perry on black holes, which are still in the editing phase.

Hawking, best known for his approachable presentation of quantum mechanics and the origins of the universe in his bestselling book, A Brief History of Time, died at the age of 76 on March 14. His ashes will be interred at Westminster Abbey near the grave of Sir Isaac Newton in November.