In the 1960s, the Soviet theoretical physicist Igor Novikov (ASC FIAN) proceeded from the theory of relativity and came to the conclusion that there must be objects in space that are opposite in properties to black holes. He called them white holes
White holes are theoretical cosmic regions that function in the opposite way to black holes. Just as nothing can escape a black hole, nothing can enter a white hole.
White holes were long thought to be a figment of general relativity born from the same equations as their collapsed star brethren, black holes. More recently, however, some theorists have been asking whether these twin vortices of spacetime may be two sides of the same coin.
To a spaceship crew watching from afar, a white hole looks exactly like a black hole. It has mass. It might spin. A ring of dust and gas could gather around the event horizon — the bubble boundary separating the object from the rest of the universe. But if they kept watching, the crew might witness an event impossible for a black hole — a belch. "It's only in the moment when things come out that you can say, 'ah, this is a white hole,'" said Carlo Rovelli, a theoretical physicist at the Centre de Physique Théorique in France.