Stephen Hawking's final thoughts on the mysteries of the cosmos have been published just weeks after his death – and it suggests a simpler theory than many experts believe.
A very basic background for those who are not prize-winning physicists: a widely held view is that after the Big Bang the universe expanded rapidly by a process known as inflation.
Some think this may still be continuing, producing a 'multiverse' with many universes out there in addition to our own.
These universes may be similar to ours, possibly with human-like inhabitants, but they could also be unrecognisable – with totally different laws of physics.
The question of how typical our universe is and finding a way to estimate how many different types there may be is a big challenge in physics.
Professor Hawking's final theory puts forward the notion that there are in fact far fewer possibilities for universe types than previously suggested.
"The behavior of our own, observable universe might not be a rare outlier, but perhaps relatively typical," said Professor David Kaiser from Massachusetts Institute of Technology – who added that the paper remains "all rather speculative".
Prof Hawking's last work was written with Thomas Hertog from Belgium's University of Leuven and is published in the Journal of High Energy Physics.
Professor Hertog said the pair had worked on the theory "for a very long time".
He told the Guardian: "I always had the impression that he [Hawking] 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."
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Professor Hawking, died in March at the age of 76, passing away peacefully in his sleep.
Eddie Redmayne, who won an Oscar for his portrayal of Professor Hawking in the 2014 biopic The Theory of Everything, led the tributes at his funeral in Cambridge.