Unknown "Structures" Not Tugging on the Universe After All?

Mysterious, unseen structures on the outskirts of creation most likely aren't tugging on our universe, according to a new study. The paper reexamines "dark flow"—an unusual, one-way motion of matter—using measurements of supernovae and the existing laws of physics.
In 2008, a team of scientists took measurements of hundreds of galaxy clusters and calculated that everything in the visible universe—and likely beyond—is flowing at 2 million miles (3.2 million kilometers) an hour in the same direction.
The data couldn't be explained by the distribution of matter in the known universe, so the scientists suggested that chunks of matter had been pushed out shortly after the big bang, and their gravity is now pulling on everything around us.
n 2010 the same team released a second study with data on twice as many galaxy clusters as their 2008 work. That research found that dark flow extends even deeper into the universe than previously reported: out to at least 2.5 billion light-years from Earth.
If proven accurate, the original version of dark flow would revolutionize our understanding of our place in the universe, said Alexander Kashlinsky, the astrophysicist at NASA's Goddard Space Flight Center in Maryland who led the 2008 team.
That's because the presence of massive structures outside the known universe could be evidence that we are in fact just one universe in a multiverse.