Resisting collapse: How matter inside a black hole can withstand gravity

Ram Brustein, A. J.M. Medved

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


How can a Schwarzschild-sized matter system avoid a fate of gravitational collapse? To address this question, we critically reexamine the arguments that led to the "Buchdahl bound," which implies that the minimal size of a stable, compact object must be larger than nine eighths of its own Schwarzschild radius. Following Mazur and Mottola, and in line with other counterexamples to the singularity theorems, we identify large negative radial pressure extending to the gravitational radius as the essential ingredient for evading the Buchdahl bound. Our results are novel although consistent with many other investigations of models of nonsingular black holes. It is shown in particular that a large negative pressure in the framework of classical GR translates into a large positive pressure once quantum physics is incorporated. In this way, a Schwarzschild-sized bound state of closed, interacting fundamental strings in its high-temperature Hagedorn phase can appear to have negative pressure and thus the ability to resist gravitational collapse.

Original languageEnglish
Article number064019
JournalPhysical Review D
Issue number6
StatePublished - 15 Mar 2019

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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