Quantized Fields and Chronology Protection

TL;DR

This paper critically examines counterexamples to the Chronology Protection Conjecture, showing that vacuum stress-energy divergences at chronology horizons are unavoidable for various scalar fields, challenging the conjecture's robustness.

Contribution

It extends analysis of vacuum states in Misner space to nonconformal and self-interacting scalar fields, demonstrating persistent divergences.

Findings

Vacuum stress-energy diverges on chronology horizons for various scalar fields.

Choosing a Rindler-type vacuum does not prevent these divergences.

Counterexamples to the Conjecture are not mitigated by vacuum state choices.

Abstract

Several recent possible counterexamples to the Chronology Protection Conjecture are critically examined. The ``adapted'' Rindler vacuum state constructed by Li and Gott for a conformal scalar field in Misner space is extended to nonconformally coupled and self-interacting scalar fields. For these fields, the vacuum stress-energy always diverges on the chronology horizons. The divergence of the vacuum stress-energy on Misner space chronology horizons cannot be generally avoided by choosing a Rindler-type vacuum state.