Mysterious 'dark flow' at the edge of the Universe

摘要

Astronomers have found that whole clusters of galaxies are moving in con-voy towards a single point in the sky. This unexpected motion appears to be separate from the expansion of the universe and the researchers even suggest that a force beyond the visible universe is the culprit. The discovery has been named "dark flow".Cosmologists have already observed two distinct effects caused by invisible entities in the universe: dark matter is known to affect the rotation of galaxies and dark energy seems to be causing the expansion of the universe to acceler-ate. Dark flow is the latest addition to this shadowy family.