[Paper Review] Black hole and baby universe in a thin film of 3He-A

Ted Jacobson, Tatsuhiko Koike|arXiv (Cornell University)|May 8, 2002

Quantum Electrodynamics and Casimir Effect15 references3 citations

TL;DR

This paper proposes a condensed matter analogue of black hole formation and evaporation using a thin film of 3He-A, where a moving domain wall creates an effective spacetime with black hole and white hole horizons. The model exhibits Hawking-like quasiparticle radiation and a temporary causal disconnection, suggesting information loss to a 'baby universe'—offering a testbed for quantum gravity questions despite unconfirmed Hawking radiation in the system.

ABSTRACT

Condensed matter black hole analogues may provide guidance in grappling with difficult questions about the role of short distance physics in the Hawking effect. These questions bear on the very existence of Hawking radiation, the correlations it may or may not carry, the nature of black hole entropy, and the possible loss of information when a black hole evaporates. We describe a model of black hole formation and evaporation and the loss of information to a disconnected universe in a thin film of 3He-A, and we explain why the existence of Hawking radiation has not yet been demonstrated in this model. [We would like this article to be accessible to researchers in both condensed matter and gravitational physics, hence we include more than the usual amount of introductory material.]

Motivation & Objective

• To explore the Hawking effect and information loss in a condensed matter system with well-understood microscopic physics.
• To model black hole formation and evaporation via a moving domain wall in a 3He-A thin film, creating an effective spacetime with horizons.
• To investigate whether Hawking radiation emerges in this system and whether information can be lost to a causally disconnected region ('baby universe').
• To provide a concrete, experimentally realizable analogue for probing foundational quantum gravity issues such as entropy and unitarity breakdown.
• To test whether short-distance physics in the system naturally produces the local vacuum state required for Hawking radiation.

Proposed method

• Model the 3He-A thin film as a relativistic effective field theory with a moving domain wall texture acting as a dynamical horizon.
• Use the effective metric derived from the fermionic quasiparticle dispersion to simulate black hole and white hole horizons.
• Analyze the causal structure using Newtonian time slices and conformal diagrams to track horizon formation and disconnection.
• Study quasiparticle pair creation at the temporary horizon, with one particle escaping and the other trapped in the ergoregion.
• Apply the concept of mode conversion and local ground state preparation near the horizon to assess the origin of Hawking modes.
• Consider Pauli blocking and back-reaction effects as potential termination mechanisms for the Hawking process.

Experimental results

Research questions

• RQ1 Can Hawking radiation emerge in a thin film of 3He-A with a moving domain wall, despite the absence of a true event horizon?
• RQ2 Does the system exhibit information loss to a causally disconnected region, analogous to a 'baby universe'?
• RQ3 How do short-distance physics and the local vacuum condition at the horizon influence the generation of Hawking modes?
• RQ4 What role does the non-equilibrium dynamics of the moving texture play in terminating the Hawking process?
• RQ5 Can this model provide insight into the origin of black hole entropy and the nature of quantum entanglement across horizons?

Key findings

• The model realizes a spacetime with a temporary black hole and white hole horizon, formed by a domain wall moving through the 3He-A film.
• Quasiparticle pairs are created at the horizon, with one particle escaping and the other trapped in the ergoregion, mimicking Hawking radiation.
• The system develops a causal disconnection after the wall stops, creating a 'baby universe' region causally separated from the exterior.
• Information carried by quasiparticles crossing the horizon may be lost to the outside world, as no superluminal return mechanism is required or expected.
• The Hawking effect is not yet experimentally demonstrated in this system, and the role of short-distance physics in generating the local vacuum remains under investigation.
• The model suggests that the origin of Hawking modes is consistent with local ground state preparation, supporting the idea that Planck-scale physics can yield the necessary vacuum state.