WHITE HOLES

White holes, which are theoretically the exact opposite of black holes, could constitute a major portion of the mysterious dark matter that's thought to make up most of the matter in the universe, a new study finds. And some of these bizzare white holes may even predate the Big Bang. A black hole is one prediction of Einstein's theory of general relativity. Another is known as a white hole, which is a black hole in reverse. Whereas nothing can escape from a black hole's event horizon, nothing can enter a white hole's event horizon. Previous research has suggested that black holes and white holes are connected, with matter and energy falling into a black hole potentially emerging from a white hole either somewhere else in the cosmos or in another universe entirely. Another theory is that when black holes expire, they become white holes. Even white holes with microscopic diameters could still be quite massive, just as black holes smaller than a grain of sand can weigh as much as the moon. It is suggested these microscopic white holes could make up dark matter. Future research will explore how such white holes from a previous universe might help to explain why time flows only forward in this current universe and not also in reverse.