Inconstant Cosmos.

"'As you go back in time, the universe is pushing [outward] less and less,' he said. 'At some point, the pressure of dark energy is zero and is exerting no force on the universe. There is no explanation for it.'" New cosmological research announced yesterday further muddles our understanding of the expansion of the early universe and (once again) casts doubt on Einstein's recently resurrected cosmological constant. "Schaefer based his findings on analysis of ultra-bright cosmic explosions called gamma-ray bursts, detected as far as 12.8 billion light-years away. He found that the most distant explosions appeared brighter than they should have been if the universe were accelerating at a constant rate."