An anonymous reader writes from a report via ScienceAlert: Physicists have confirmed the existence of pear-shaped nuclei, which challenges the fundamental theories of physics that explain our Universe. "We've found these nuclei literally point towards a direction in space. This relates to a direction in time, providing there's a well-defined direction in time and we will always travel from past to present," Marcus Scheck from the University of the West of Scotland told Kenneth MacDonald at BBC News. Until recently, it was generally accepted that nuclei of atoms could only be one of three shapes: spherical, discus, or rugby ball. The first discovery of a pear-shaped nucleus was back in 2013, when physicists at CERN discovered isotope Radium-224. Now, that find has been confirmed by a second study, which shows that the nucleus of the isotope Barium-144 is also asymmetrical and pear-shaped. In regard to time travel, Scheck says that this uneven distribution of mass and charge caused Barium-144's nucleus to "point" in a certain direction in spacetime, and this bias could explain why time seems to only want to go from past to present, and not backwards, even if the laws of physics don't care which way it goes.