"It from Bit": The Hartle-Hawking state and quantum mechanics for de Sitter observers

arXiv:2602.05939 · hep-th, gr-qc, quant-ph · Submitted 2026-02-05 · Read on arXiv

hep-th, gr-qc, quant-ph

Submitted: 2026-02-05

Updated: 2026-09-21

Comments: 45+8 pages; v2: clarifications in Sec. 4.4.2; added Sec. 4.4.5 on the Hartle-Hawking wave function; added Footnote 2; v3: minor clarifications; published version in JHEP

Journal ref: JHEP 09 (2026) 252

DOI: 10.1007/JHEP09(2026)252

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

Terminology

• Hilbert Space — 91× in this paper · explained in 2 episodes
• Trace — 19× in this paper · explained in 2 episodes
• Consistency — 7× in this paper · explained in 3 episodes
• Entanglement — 6× in this paper · explained in 3 episodes
• Accuracy — 3× in this paper · explained in 1 episode
• Entanglement Entropy — 1× in this paper · explained in 2 episodes
• Generalization — 1× in this paper · explained in 13 episodes
• No-Go Theorem — 1× in this paper · explained in 2 episodes
• Quantization — 1× in this paper · explained in 12 episodes
• SYK Model — 1× in this paper · explained in 2 episodes
• alpha — 1× in this paper · explained in 1 episode

Sources

• The Page curve of Hawking radiation from semiclassical geometry
• Replica wormholes and the black hole interior
• Transcending the ensemble: baby universes, spacetime wormholes, and the order and disorder of black hole information
• Closed universes in two dimensional gravity
• Closed universes, factorization, and ensemble averaging
• The black hole interior from non-isometric codes and complexity
• Cosmology from random entanglement
• Do holographic CFT states have unique semiclassical bulk duals?
• Further Evidence Against a Semiclassical Baby Universe in AdS/CFT
• Baby Universes, Holography, and the Swampland
• Semiclassical 3D gravity as an average of large-c CFTs
• Covariant phase space with boundaries
• Defects in Jackiw-Teitelboim Quantum Gravity
• Matrix Models and Deformations of JT Gravity
• Dilaton-gravity, deformations of the minimal string, and matrix models
• Replica Wormholes and the Entropy of Hawking Radiation
• Entanglement Wedge Reconstruction and the Information Paradox
• The entropy of bulk quantum fields and the entanglement wedge of an evaporating black hole
• Observations of Hawking radiation: the Page curve and baby universes
• The Page curve and baby universes

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• Energy Transmission Across Holographic Conformal Interfaces in General Dimensions