Bartnik mass minimizing initial data sets and improvability of the dominant energy scalar

TL;DR

This paper explores the concept of improvability of the dominant energy scalar in initial data sets, establishing conditions for non-improvability, and advances understanding of Bartnik mass minimization and related conjectures, with implications in higher dimensions.

Contribution

It introduces the concept of improvability of the dominant energy scalar, derives consequences of non-improvability, and characterizes Bartnik mass minimizing initial data sets, advancing the stationary conjecture.

Findings

Non-improvable initial data sets without symmetries sit inside null perfect fluid spacetimes with Killing vectors.

The dominant energy scalar is almost always improvable in a precise sense.

Counterexamples to positive mass and stationary conjectures exist in dimensions greater than eight.

Abstract

We introduce the concept of improvability of the dominant energy scalar, and we derive strong consequences of non-improvability. In particular, we prove that a non-improvable initial data set without local symmetries must sit inside a null perfect fluid spacetime carrying a global Killing vector field. We also show that the dominant energy scalar is always almost improvable in a precise sense. Using these main results, we provide a characterization of Bartnik mass minimizing initial data sets which makes substantial progress toward Bartnik's stationary conjecture. Along the way we observe that in dimensions greater than eight there exist pp-wave counterexamples (without the optimal decay rate for asymptotically flatness) to the equality case of the spacetime positive mass theorem. As a consequence, there exist counterexamples to Bartnik's stationary and strict positivity conjectures in those dimensions.