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Four inequivalent paths to thermality in Minkowski spacetime

Rakesh K Jha*, Akhil U. Nair†, Prasant Samantray‡, and Sashideep Gutti§

  • *Contact author: p20230070@hyderabad.bits-pilani.ac.in
  • †Contact author: p20200473@hyderabad.bits-pilani.ac.in
  • ‡Contact author: prasant.samantray@hyderabad.bits-pilani.ac.in
  • §Contact author: sashideep@hyderabad.bits-pilani.ac.in
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Phys. Rev. D 114, 045009 – Published 12 August, 2026

DOI: https://doi.org/10.1103/1ypz-kvf8

Abstract

In this article, we explore the answer to an inverse question to the Unruh effect. Given a two-dimensional Rindler wedge R with a thermal distribution of massless scalar particles, we explore the supersets of R, whose reduced state yields the observed particle content in R. If we restrict our analysis to particle content close to the Rindler horizon in R, we show that the answer to the inverse question is not unique. The analysis is done using two methods, the first uses Bogolibov coefficients and the second method uses Virasoro anomaly. We identify four inequivalent paths with various “parent” spacetimes of R from which we can arrive at the given particle content in R. We show that the supersets are Minkowski spacetime, a Rindler wedge in vacuum, a Rindler wedge with a thermal flux of left-moving particles and lastly a Rindler wedge with a thermal flux of right moving flux of particles. We also show an interesting phenomenon; flux to density conversion, wherein a thermal flux of either left-moving or right-moving particles can be converted to thermal density of particles involving both left-moving and right-moving particles. The analysis presents a natural possibility to define the information entropy for a given Rindler wedge. This stems from the fact that a given Rindler wedge with its particle content could have originated from various supersets found in the article. Based on the analysis done in the article, we present qualitative arguments regarding the possibility that the continuous evaporation of a black hole might be punctuated by a series of pauses and bursts of radiation.

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Phys. Rev. D 114, 045009– Published 12 August, 2026
  • Received 21 April 2026
  • Accepted 15 July 2026
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