​​​​​​​ ISTANBUL   Dark energy, long thought to drive the accelerating of the expansion of the universe, may not exist, according to a groundbreaking study. The research, based on enhanced light-curve analysis of "type Ia supernovae," suggests the universe expands in a "lumpy" and uneven manner rather than uniformly. Published Thursday in the journal, Monthly Notices of the Royal Astronomical Society, the study was led by professor David Wiltshire of the University of Canterbury in New Zealand.