Poking a Dimple in a Black Hole Shows Explicitly that Black Hole Complementarity Violates Causality

TL;DR

The paper demonstrates that black hole complementarity leads to causality violations by showing how information can be read outside a black hole before it is written, through a thought experiment involving a dimple in the horizon.

Contribution

It provides a thought experiment that explicitly shows black hole complementarity violates causality by allowing information to be read before it is inscribed.

Findings

Black hole complementarity permits reading messages before they are written.

A dimple in the horizon can be used to encode and read information.

Causality is violated under the assumptions of black hole complementarity.

Abstract

A massive ball at a fixed distance just outside a black hole (BH) pokes a dimple in the BH by locally depressing the apparent horizon. Analysis of the effect of the dimple on the event horizon shows that if BH Complementarity (BHC) is valid then it is possible to inscribe any message on the surface of the BH; while the message disappears as soon as it is written it can be read by anyone outside the BH during a finite, yet potentially extended period before it is written, thereby violating causality.