The Multiverse theory states that our universe is only one in a large number of possible universes that have sparked into existence after the Big Bang. Supported by many world-class physicists, including Neil deGrasse Tyson and the late Stephen Hawking, the idea has been around since the 1980s and has served, in part, as a way to explain the surprisingly low amount of dark energy found in our universe.
Dark energy is the mysterious force that drives the ongoing expansion of the universe. Unlike any other force, dark energy doesn't slow down with time, but actually keeps accelerating, and it makes up around 70 percent of the entire universe, notes Science Alert.
However, the current theories on the origin of the universe predict that there should actually be more dark energy in our universe than is observed. This points to an error in calculations, considering that — as per the same predictions — a larger amount of dark energy would make the universe expand too fast for stars and planets to form, meaning that we wouldn't exist.
According to Cosmos Magazine, the Multiverse theory tries to explain this calculation anomaly. The theory states that each of the worlds in the Multiverse holds a different percentage of dark energy and that, through a lucky coincidence, we managed to pop up in one where dark energy is low enough for life to appear.
Yet a pair of studies published last week in the Monthly Notices of the Royal Astronomical Society have proven that the impact of dark energy on the formation of stars and planets isn't as severe as previously believed.
Conducted by Durham University in the U.K., in collaboration with three Australian universities, the University of Sydney, the Western Sydney University, and the University of Western Australia, the research uncovered that increasing the amount of dark energy in our universe by as much as a few hundred times would only have a modest impact on star birth and planet formation.
In turn, this suggests that the Multiverse, if it in fact exists, could be teeming with life, EurekAlert reports. Since higher levels of dark energy would still allow life in the universe to exist, this hints at the possibility that life could also have appeared in other universes despite their estimated greater percentage of dark energy.Research co-author Dr. Luke Barnes, from Western Sydney University, states that the two studies — available here and here — indicate that the lucky coincidence used by the Multiverse theory to explain how our universe came to be "seems a little too lucky."
"The Multiverse was previously thought to explain the observed value of dark energy as a lottery — we have a lucky ticket and live in the universe that forms beautiful galaxies which permit life as we know it."As Barnes puts it, "our ticket" is "more special than it needs to be for life [to exist]."
"This is a problem for the Multiverse; a puzzle remains," he points out.
The international team of scientists made this discovery after creating a model of the universe using the tools of the EAGLE project (Evolution and Assembly of GaLaxies and their Environments) — one of the most realistic simulations of the observed universe, which encompasses models for around 10,000 galaxies over a distance of 300 million light-years.
"Our simulations show that even if there was much more dark energy or even very little in the Universe then it would only have a minimal effect on star and planet formation, raising the prospect that life could exist throughout the Multiverse," said research co-author Jaime Salcido, from Durham University's Institute for Computational Cosmology."We asked ourselves how much dark energy can there be before life is impossible?" explained Dr. Pascal Elahi, from the University of Western Australia.
"Even increasing dark energy many hundreds of times might not be enough to make a dead universe," he said.
The team points out that these results deepen the "frustrating puzzle" of why our universe has such low amounts of dark energy considering that, as per the simulations, this isn't necessarily a prerogative for life to emerge.
"We have found in our simulations that universes with much more dark energy than ours can happily form stars. So why such a paltry amount of dark energy in our Universe?" asks Prof. Richard Bower, also from Institute for Computational Cosmology.
The simulations revealed that, if we indeed live in a Multiverse, our universe should contain 50 times more dark energy than currently estimated.
As Bower points out, a new law of dark energy is required in order to explain why our universe is so special in terms of dark energy distribution.
"I think we should be looking for a new law of physics to explain this strange property of our universe, and the Multiverse theory does little to rescue physicists' discomfort."