SYDNEY: Astronomers have found the best evidence yet for the weird idea that our universe is one of many in the ‘multiverse’. What’s more, these parallel universes seem to be exerting a strange force on our own, causing galaxy clusters to stream across space towards the edge of the known universe.
The new evidence comes from studies of ‘bumps and wiggles’ in the temperature of the cosmic background radiation (CMB), the leftover afterglow of the Big Bang.
U.S. cosmologist Sasha Kashlinsky of the Goddard Space Flight Centre in Greenbelt, Maryland, and co-workers measured slight changes in the CMB using NASA’s Wilkinson Microwave Anisotropy Probe (WMAP). Slight deviations in the general expansion of the universe reveal the speed and direction of clusters of galaxies.
Last year, Kashlinsky’s team found an unusual pattern in the movements of galaxy clusters. Instead of expanding at a uniform rate, as predicted by Einstein’s general theory of relativity and theories of dark energy, clusters of galaxies stream in one particular direction and at greater than expected speeds. They called this weird phenomenon the ‘dark flow’.
Now, new research from the team has confirmed and extended this flow to three billion light-years from Earth, about one-fifth of the way across the universe. The results have been submitted to The Astrophysical Journal.
Best evidence for the multiverse
The mystery is about what exactly is ‘pulling’ at the galaxy clusters to cause the flow, and this is where parallel universes come in.
Some theories of the beginning of the universe require multiple universes, which are mysteriously ‘entangled’, much like quantum particles at very small scales. The controversial theory suggests that although we can’t see them, these parallel universes can exert a force on our own universe which provokes this ‘dark flow’.
“If the flow extends all the way to the cosmological horizon, as our results likely suggest, then its origin likely is tied to the overall pre-inflationary structure of space-time [the first milliseconds of the Big Bang] and may point to the multiverse in one form or another,” Kashlinsky said. “We are continuing the project and expect that our future measurements would answer this possibility much more definitively.”
One proponent of the multiverse theory, cosmologist Laura Mersini-Houghton from the University of North Carolina at Chapel Hill, U.S., says Kashlinsky’s findings are the “most straightforward indication of the existence of the multiverse.”
“A multiverse extension of physics revolutionises our understanding of nature. It enables us to see the world beyond the horizon of the visible universe and reinforces the Copernican principle that our universe is neither special nor at the centre of cosmos. It is profound,” commented Mersini-Houghton.
Fits the data
Mersini-Houghton points out the parallel universe theory predicted dark flow and even closely matches the speed of the dark flow as measured by Kashlinksy.
But while admitting that the dark flow was “worrying” to conventional physics theories such as general relativity, Australian cosmologist Warrick Couch of the Swinburne University of Technology in Melbourne said he didn’t think it was direct proof of parallel universes.
“It adds an interesting observational fact to the debate, but I’d be reluctant to say it’s completely proof of the multiverse theory,” said Couch.”I think there are so many multiverse theories and there are so many parameters that it’s hard to test them all.”
Follow Cosmos on Twitter!
The study on arXiv.org