If dark matter and dark energy were not mysterious enough, now astronomers have discovered that over 1000 clusters of galaxies are streaming in one direction at the blistering speed of 1000 kilometers/second, or about 2 million MPH.

This "dark flow" is explainable by the presence of some enormous concentration of matter drawing the galaxy clusters toward it, and scientists suspect this object might be another universe. This finding was predicted in 2005 by an astronomer at North Carolina U. and now seems to be confimed, although the normal scientific doubts remain.

Along with entanglement, inflation, the big bang, and other mysteries yet to be understood, this finding is another reminder that the universe is far more complex than we can possibly guess.  

Source: The Astrophysical Journal Letters Vol. 686 page L49