The collapse of a star at the end of its life cycle could lead not only to a black hole but also to an ultra-compact star – a so-called gravastar – which resembles a black hole from the outside. This is the conclusion reached by two theoretical physicists at Goethe University. They have discovered a solution to the equations of Einstein’s General Relativity according to which the gravitational collapse of a star does not necessarily have to end in a black hole. According to their calculations, a new mini universe could form inside the collapsing star. The Big Bang would reverse the enormous gravitational forces and give rise to a gravastar filled with dark energy.