Massive Islands

TL;DR

This paper explores how the mass of the graviton influences the formation of entanglement islands in holographic calculations of the Page curve, providing a simple model in various dimensions and discussing implications for massless gravity.

Contribution

It introduces an analytically tractable model of island formation in different dimensions by varying graviton mass, highlighting the impact of zero graviton mass on island contributions.

Findings

Massive gravitons are essential for reliable Page curve calculations in higher dimensions.

Island contributions vanish as graviton mass approaches zero.

The model simplifies understanding of entanglement islands in holography.

Abstract

We comment on the role of the graviton mass in recent calculations of the Page curve using holographic ideas. All reliable calculations of the Page curve in more than 2+1 spacetime dimensions have been performed in systems with massive gravitons. A crucial ingredient in these calculations is the formation of islands, regions that contribute to the entropy of degrees of freedom located elsewhere. While most often simply ignored, it is indeed true that mass of the graviton does not appear to significantly affect the calculations that appeared in the literature. We use the freedom to change the graviton mass to give an extremely simple model of analytically tractable island formation in general dimensions. We do however note that if one attempts to take the limit of zero graviton mass, any contribution from the islands disappears. This raises the question to what extent entanglement islands can play a role in standard massless gravity.