Not all stars turn into black holes

In 2011, a scientific article raised the exciting but problematic possibility that black holes could form more easily than previously thought. Until then, the scientific community believed that only very massive stars at the end of their lives could become black holes. These circumstances would allow for a sufficiently large amount of matter to be confined in a space small enough for their formation. Hirotada Okawa, Vitor Cardoso, and Paolo Pani, from the Multidisciplinary Center for Astrophysics (CENTRA) at the Instituto Superior Técnico, revisited and updated the contours of this problem. The results of their study will be published in the journal Physical Review D and reinforce the prevailing view: black holes are extremely rare in our universe.

The article published by two Polish scientists in 2011 suggested that in anti-de Sitter spacetime black holes form regardless of the initial conditions. Anti-de Sitter spacetime is the simplest solution to Einstein's equations of general relativity. The Polish researchers showed that anti-de Sitter space-time can act like an open box with a mirrored interior. The reflection of matter inside the box could thus create a point where the density is infinite and form a black hole.

Using their Baltasar Sete Sóis supercomputer, CENTRA researchers ran a series of simulations to solve Einstein's equations and determine whether these 'boxes' exist in the real universe. The research group concluded that in the Universe, the 'boxes' would allow energy to dissipate and that in the case of less massive objects, such as our Sun, the dissipated energy would be sufficient to block the formation of a point with infinite density. Paolo Pani, an FCT researcher selected in Call , summarizes the results: "We found that in realistic cases, matter collapse can occur, but it is not that easy."

Vitor Cardoso adds that the future of a star is not necessarily to become a black hole – "Gravity doesn't always win!"