The Penrose diagram of a maximally-extended spherical charged black hole. A traveler intending to access the exterior universe (on the top right) must pass through the inner horizon, in red.

Black holes are amongst the most exotic objects predicted by the theory of General Relativity. In the simplest mathematical solutions corresponding to a charged or spinning black hole, the interior of the black hole provides a bridge to other universes. How relevant is this fantastic picture to our realistic universe? Will quantum effects block the possibility of a journey between universes through a black hole?

In a paper published recently in the Physical Review Letters journal, Noa Zilberman, Adam Levi, and their advisor Amos Ori from our department have shown for the first time via an explicit computation the divergence of quantum fluxes at the inner horizon of a charged black hole. This is a meaningful step towards answering the traversability question, as well as other deep questions regarding the nature of spacetime in black hole interiors.