Mysterious 'dark flow' may be sign of neighboring universe

London, November 17 : An analysis of the mysterious 'dark flow' seen in outer space has suggested that something big is out there beyond the visible edge of our universe, which may be a sign of a neighboring universe.

Last year, Sasha Kashlinsky of the Goddard Space Flight Center in Greenbelt, Maryland, and colleagues identified an unusual pattern in the motion of around 800 galaxy clusters.

According to a report in New Scientist, they studied the clusters' motion in the "afterglow" of the big bang, as measured by the Wilkinson Microwave Anisotropy Probe (WMAP).

The photons of this afterglow collide with electrons in galaxy clusters as they travel across space to the Earth, and this subtly changes the afterglow's temperature.

The team combined the WMAP data with X-ray observations and found the clusters were streaming at up to 1000 kilometres per second towards one particular part of the cosmos.

Many researchers argued the dark flow would not turn up in later observations, but now the team claim to have confirmed its existence.

Their latest analysis reveals 1400 clusters are part of the flow, and that it continues to around 3 billion light years from Earth, a sizable fraction of the distance to the edge of the observable universe.

This is twice as far as seen in the previous study.

The dark flow appears to have been caused shortly after the big bang by something no longer in the observable universe.

It has no effect today because reaching across this horizon would involve traveling faster than light.

There could be an exotic explanation.

Laura Mersini-Houghton of the University of North Carolina, Chapel Hill, thinks the flow is a sign of a neighboring universe.

If the tiny patch of vacuum that inflated to become our universe was quantum entangled with other pieces of vacuum - other universes - they could have exerted a force from beyond the present-day visible horizon.