Historical research guide · 0488 · 2026

Analogue gravity (2026 edition)

Carlos Barceló · Stefano Liberati · Matt Visser

In one minute

Carlos Barceló, Stefano Liberati and Matt Visser have rewritten their standard review of analogue gravity — the programme that builds working models of curved spacetime out of ordinary matter, most famously sound in a flowing fluid, where supersonic flow makes a horizon sound cannot escape. This 2026 edition covers the fifteen years since the previous one, and the headline is that the field changed character: what was a mostly theoretical enterprise is now driven by table-top experiments, with well over fifty doctoral theses behind it and a community that mixes relativists, condensed-matter theorists and experimentalists. Hawking radiation has been produced in the laboratory, in a Bose-Einstein condensate at a temperature of about one nanokelvin, along with superradiance and cosmological particle creation. The authors argue that the imperfection of the models is their strength: because the analogue systems break Lorentz invariance at short distances and the effects survive anyway, we now know those effects do not depend on the microphysics underneath.

Connection

Chapter 5 rests on treating a medium’s excitations as living on an effective metric, and this is the reference edition of that idea — now with fifteen further years of laboratory results attached, which is exactly what chapter 1’s evidence ladder asks for. The 2011 edition is covered separately at /library/stm-9d9474c4b5; read that one for the derivation of the acoustic metric, and this one for where the experiments have got to.

From the source

This is a major new edition rather than a reprint: the authors describe it as a major update and upgrade adding a survey of the last fifteen years, with the reference count rising from 702 to 1285, a completely rewritten history split into Historical, Classical, Early Modern, Late Modern and Contemporary periods, a new subsection on quantum fluids of light, a massively updated experimental section, and new material on the Marolf theorem.Front matter, ‘Change summary’ and ‘Change details’; Acknowledgements, change list
Analogue gravity has become an experimental field. Experimental groups took up the challenge from around 2008, several now run analogue-gravity experiments regularly, well over fifty related master’s and doctoral theses have been defended, and the authors judge that table-top experiments are nowadays just as relevant, if not dominant, in settling the agenda.Section 1, Introduction; Section 8, Conclusions
Effects that were once purely theoretical have been reproduced in the laboratory: spontaneous Hawking radiation from a single horizon in a Bose-Einstein condensate, at a Hawking temperature of about 1.2 nanokelvin; superradiant scattering, seen in a water tank and again in a photon superfluid; and analogue cosmological particle creation in a quenched three-dimensional quantum fluid of light.Section 6, Experimental efforts, and its opening highlight; Section 5 on the Hawking temperature; Section 8, Conclusions
The Hawking effect is robust against the microphysics. Analogue systems break Lorentz invariance at short distances and the effect survives anyway, so the authors treat the imperfection of the models as a strength rather than a weakness: it breaks degeneracies and exposes subtleties that the exact gravitational calculation hides.Section 8, Conclusions, third and fourth paragraphs
The forward claim is about emergence: analogue models supply toy models for the interplay between the large-scale, classical, continuum structure of spacetime and the microphysics from which it might emerge, and the authors regard those lessons as available to the quantum-gravity community and so far taken up only rarely.Section 8, Conclusions, fifth paragraph; Section 7 on hints for quantum gravity
The authors mark the boundary of the analogy themselves, in a footnote on the first page of the introduction: an analogue spacetime metric is a metric seen by excitations of a medium, and manipulating it does not produce a physical change in the gravitational field.Section 1, Introduction, footnote 2

The way in

https://doi.org/10.1007/s41114-026-00064-9

Historical source-access record. This guide links to the original; it does not reproduce the paper text.

Living Reviews in Relativity (2026) 29:2; received 30 January 2025, accepted 12 February 2026. The licence statement is printed in the article — ‘Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License’ — and the article itself states that it is a revised version of doi:10.12942/lrr-2011-3, a major update and expansion whose reference count rises from 702 to 1285. The 2011 edition is a separate sheet on this site, /library/stm-9d9474c4b5, published under a NoDerivs licence and therefore carried there as a summary. This sheet is the new edition, kept short on purpose: the review runs to 222 pages and roughly 106,000 words, so the abstract, the introduction with its overview and motivations, the authors’ own change summary and the conclusions are reproduced and the eight substantive sections are noted as omitted. The Springer PDF is behind a bot check, so the text follows the identical copy served by INSPIRE-HEP.

How to cite it

Carlos Barceló, Stefano Liberati, Matt Visser (2026) Analogue gravity (2026 edition) doi:10.1007/s41114-026-00064-9

Where it sits in the curriculum

The vacuum as a quantum fluid