Massive and Dark
"Expansion of the Universe is not uniform. Individual motions of galaxies can oppose the Hubble flow, like trout swimming upstream. The Milky Way and thousands of other galaxies are falling at 600 km/sec toward an unseen mass called the Great Attractor. This object has the mass of 10^16 Suns or 100,000 galaxies! It may be a true Black Hole, so monstrously massive that nothing can escape. There is evidence of another Great Attractor some 700 million years away.
"These monsters could be common, yet they are not counted in mass surveys. The missing 2/3 ascribed to "dark energy" may be hidden from us. It is foolish to think that humans know all that is out there. That is like Wile E. Coyote, Super Genius not realising that he is falling into an abyss."
Today another research group led by Mike Hudson from University of Waterloo reports that our region of the Universe is not expanding uniformly. One half of the sky appears to be expanding faster than the other half. Researchers conclude that massive, unseen structures exist in the Universe. These great attractors would not lie outside the Universe, but beyond our local group of galaxies. This will require revisions of the tired old cosmological model. UPDATE: Preprint of the new paper is entitled Consistently Large Flows on Scales of 100 Mpc/h: A Challenge for the Standard LCDM Cosmology.