https://en.m.wikipedia.org/wiki/Dark_flow
"According to standard cosmological models, the motion of galaxy clusters with respect to the cosmic microwave background should be randomly distributed in all directions. However, analyzing the three-year Wilkinson Microwave Anisotropy Probe (WMAP) data using the kinematic Sunyaev-Zel'dovich effect, astronomers Alexander Kashlinsky, F. Atrio-Barandela, D. Kocevski and H. Ebeling found evidence of a "surprisingly coherent" 6001000 km/s[1][2] flow of clusters toward a 20-degree patch of sky between the constellations of Centaurus and Vela."
There is directionality to matter in the Universe which can't be explained by the Big Bang.
"NASA's Goddard Space Center considered that this could be the effect of a sibling universe or a region of space-time fundamentally different from the observable universe."
There is no reason to hypothesize sibling universes. It is much more likely caused by a larger version of what we see throughout the universe. A Universal black hole powering the Universal polar jet we exist in explains the 'dark flow'.