With a scientific article published after his death, Stephen Hawking has revived the debate on a deeply divisive question for cosmologists: is our universe just one of many in an infinite, ever-expanding "multiverse"?
After a mindset, the cosmos began to expand exponentially after the Big Bang.
In most parts, this expansion or "inflation" continues forever, except for a few pockets where it ends.
These Bags Here, universes like ours are created, often compared to "bubbles" in an ever-expanding ocean, the multiverse.
Many scientists do not like the idea, including Hawking, who said in an interview last year, "I've never been a fan of the multiverse."
Living in an ever-expanding multiverse would mean that the laws of physics and chemistry can vary from one universe to another, a concept that scientists accept.
In his recent contribution to cosmology Hawking -with co-author Thomas Hertog of the University of KU Leuven in Belgium ̵
"We do not depend on a single, unique universe," Cambridge University quoted Hawking as saying about the paper submitted before his death on March 14 and published this week in the Journal of High Energy Physics.
"However, our results imply a significant reduction of the multiverse to a much smaller selection of possible universes."
The new hypothesis is based on a branch of theoretical physics, string theory, and concludes that the cosmos is "definitely finite," Hertog told AFP, although it still consisted of numerous universes.
"It's a debate that touches the foundations of cosmology," Hertog said.
"The basic question is whether we can gain a deeper understanding of where the laws of nature come from and whether they are unique."
Not everyone likes the new theory.
"The idea that we live in a 'multiverse' is a fringe idea in a small part of a section of the physics community," said theoretical physicist Sabine Hossenfelder of the Frankfurt Institute for Advanced Studies
" Nobody who practices serious science works with the multiverse because it is completely useless, "she told AFP.
The main problem, according to Hossenfelder, is that each multiverse theory is "underdetermined" and "does not contain enough information to make calculations. "
For critics, a multiverse theory makes our understanding of our own universe more difficult.